Transportation is Destiny: Design for Happy People, Not Happy Cars

by Dom Nozzi

The following is a summary of a talk I was invited to give at a PLAN-Boulder County forum on Friday, January 24. As a town and transportation planner, I cautioned Boulder not to put too much emphasis on easing car traffic flows—particularly by such conventional methods as adding a second turn lane at intersections or requiring a developer to provide too much car parking. I described the ingredients of a healthy, vibrant city, summarized how a seemingly beneficial city objective of reducing traffic congestion can often undermine important Boulder objectives, and offered a number of strategies that would help Boulder both properly manage transportation and promote its long-range goals.

A great city is compact, human scaled, has a slow speed center, and promotes gatherings of citizens that catalyze “synergistic interaction” (brilliant ideas and innovations, as the sum becomes greater than its parts). Most importantly, a quality city does exceptionally well in promoting “exchanges” of goods, services, and ideas, which is the most important role of a city, and is best promoted by the interaction that occurs through compact community design.

About 100 years ago, automakers, home builders, and oil companies (“the Sprawl Lobby”) started realizing that they could make lots of money by creating what has since become a self-perpetuating vicious cycle in communities. If communities could be convinced to ease the flow of car traffic by building enormous highways and parking lots (and subsidizing car travel by having everyone—not just motorists—pay for such roads, parking, and gasoline), huge amounts of money could be made selling cars, homes and gasoline. The process eventually was feeding on itself in a growing, self-perpetuating way, because the highways, parking and subsidies were forcing and otherwise encouraging a growing number of Americans to buy more and more cars, use more and more gasoline, and buy sprawling homes that were further and further from the town center. Why? Because the subsidized highways and gasoline were powerfully promoting community dispersal, high speeds, isolation, and an insatiable demand for larger highways and parking lots. Each of these factors were toxic to a city, led to government and household financial difficulties, destroyed in-town quality of life (which added to the desire to live in sprawl locations), and made travel by transit, bicycle or walking increasingly difficult and unlikely (an added inducement to buy more cars).

The inevitable result of the Sprawl Lobby efforts has been that cities throughout America are dying from the “Gigantism” disease.

The “Gigantism” Disease

One of the most important problems we face is that cars consume enormous amounts of space. On average, a person in a parked car takes up about 17 times more space than a person in a chair. And when moving, a motorist can take up to 100 times as much space as a person in a chair. Cities are severely diminished by this level of wasteful use of land by cars—particularly in town centers (where space is so dear), and especially in communities such as Boulder, where land is so expensive.

Overemphasis on car travel breeds and spreads the gigantism “infection,” and promotes ruinously higher travel speeds. What happens when we combine the gigantism and high speeds with the “travel time budget” (humans tend to have a budget of about 1.1 hours of round-trip commuting travel each day)?

People demand larger highways and parking lots. Gigantic highways, overpasses, and asphalt seas of parking are necessary to accommodate the space-hogging, high-speed needs of the growing number of cars. This process dramatically increases the “habitat” for cars, and because such places are so utterly inhospitable to people, substantially shrinks the habitat for people.

Because it is so dangerous, unpleasant, and infeasible to travel on these monster highways by bicycle, walking, or transit (what economists call “The Barrier Effect”), an endlessly growing army of motorists and sprawl residents is thereby created, which, of course, is a financial bonanza for the Sprawl Lobby.

It is surprising and disappointing that Boulder has, on numerous occasions, shown symptoms of the gigantism disease (surprising because citizens and city staff are relatively well-informed on transportation issues). A leading concern in Boulder is the many intersections that have been expanded by installing double left turn lanes. Installing a single left turn lane historically resulted in a fair improvement in traffic flow, but when a second left turn lane is installed, intersections typically suffer from severely diminished returns. There is only a tiny increase in traffic accommodated (and often, this increase is short-lived) and this small benefit is offset by a huge required increase in walk time for crosswalks that are now very lengthy to cross on foot (which necessitates a very long “walk” phase for the crosswalk). Indeed, some traffic engineers or elected officials are so intolerant of the time-consuming long walk phase that many double-left turn intersections actually PROHIBIT pedestrian crossings by law.

These monster double left turn intersections destroy human scale and sense of place. They create a place-less, car-only intersection where walking and bicycling (and, indirectly, transit) trips are so difficult and unpleasant that more trips in the community are now by car, and less by walking, bicycling and transit. And those newly-induced car trips, despite the conventional wisdom, actually INCREASE greenhouse gas emissions (due to the induced increase in car trips).

Double left turn lanes (like big parking lots and five- or seven-lane highways) disperse housing, jobs, and shops in the community, as the intersection—at least briefly—is able to accommodate more regional car trips. Because the intersection has become so inhospitable, placeless and lacking in human scale, the double left turn repels any residences, shops, or offices from being located anywhere near the intersection, and thereby effectively prevents the intersection from ever evolving into a more walkable, compact, village-like setting.

The following chart shows that, because of the enormous space consumption caused by higher-speed car travel, land consumption rate increases are far out-pacing growth in community populations. For example, from 1950 to 1990, the St. Louis population grew by 35 percent. Yet land consumption in St. Louis grew by 354 percent during that same period.

Given all of this, a centerpiece objective of the Boulder Transportation Master Plan (no more than 20 percent of road mileage is allowed to be congested) may not only be counterproductive in achieving many Boulder objectives, but may actually result in Boulder joining hands with the Sprawl Lobby.

The congestion reduction objective has a number of unintended, undesirable consequences. The objective tells Boulder that the highly desirable tactic of “road diets” (where travel lanes are removed to create a safer, more human-scaled street that can now install bike lanes, on-street parking, and wider sidewalks) are actually undesirable because they can increase congestion. The objective provides justification for looking upon a wider road, a bigger intersection, or a bigger parking lot as desirable, despite the well-documented fact that such gigantic facilities promote sprawl, car emissions, financial difficulties, higher taxes, and lower quality of life, among other detriments.

The objective also tells us that smaller, more affordable infill housing is undesirable—again because such housing can increase congestion.

The Shocking Revolution

The growing awareness of the problems associated with easing car travel (via such things as a congestion reduction objective) is leading to a shocking revolution across the nation. Florida, for example, now realizes that if new development is only allowed if “adequate” road capacity is available for the new development (which is based on “concurrency” rules in Florida’s Growth Management law), the state is powerfully promoting sprawl. Why? Because the available road capacity tends to only be found in sprawl locations. In-town locations, where new development tends to be much more desirable, is strongly discouraged by this Florida concurrency rule because in-town locations tend to have no available road capacity (due to existing, more dense development in town).

As an aside, “concurrency” is a rule that says new development is not allowed if it will lower service level standards adopted by the community. For example, standards might state that there must be at least 10 acres of parkland provided for every 1,000 residents. While concurrency is clearly a good idea for such things as parks and water supply and schools, it is counterproductive for roads.

The shocking revolution in Florida, then, is that the state is now allowing local governments to create “exception areas” for road congestion. If the community can show that it is providing adequate bicycle, pedestrian and transit facilities, the state will grant the local government the ability to create road exceptions so that the road congestion avoidance strategy brought by Florida’s road concurrency rule does not significantly encourage new sprawl and discourage in-town, infill development.

Similarly, California is now acknowledging the unintended, undesirable effects of past efforts to ensure that roads are “free-flowing” for car traffic. “Free flowing” car traffic tends to be measured with “level of service” (LOS) measures. Road LOS is a measure of traffic delay. An intersection (or road) where a car must wait for, say, three cycles of a traffic signal to be able to proceed through the intersection might be given an LOS rating of “F.” An intersection where a car can proceed through an intersection without such delay is given an LOS rating of “A.”

California now realizes that too often, building wider highways or stopping new development as a way to maintain free-flowing car traffic (LOS “A”) is substantially counterproductive. The state now realizes that maintaining or requiring easy, free-flowing car traffic increases greenhouse gas emissions (shocking, since the opposite was formerly believed), increases the number of car trips, and decreases the number of walking, bicycling and transit trips. Free-flowing road “LOS” measures are therefore now being phased out in California.

The “congestion reduction” objective in Boulder’s transportation plan is, in effect, a “happy cars” objective that equates easy car travel with quality of life and sustainability. One important reason why this “happy cars” objective is counterproductive is that cars and people have dramatically different needs and desires—needs and desires that are significantly and frequently in conflict. For example, designing shopping for happy people means the creation of smaller, human-scaled settings where buildings rather than parking lots are placed next to the streetside sidewalk. Where streets are only two or three lanes wide and designed for slow-speed car travel. Where street trees hug the street.

Designing shopping for happy cars, by strong contrast, requires huge car-scaled dimensions. Giant asphalt parking lots are placed between the now giant retail store and the street, which invites easy car parking (but loss of human scale, sense of place, and ease of walking). Streets become what Chuck Marohn calls “stroads”:  5- or 7-lane monster roads intended for dangerous, inhospitable high-speeds. They are roads where streets belong, but their big size and high speeds make them more like roads. Street trees are frequently incompatible with happy cars, as engineers fear cars might crash into them.

Again, this comparison shows that by promoting “happy cars,” Boulder’s congestion reduction objective is undermining its important quality of life and city-building objectives.

Indeed, Enrique Penalosa, the former mayor of Bogota, Columbia, once stated that “a city can be friendly to people or it can be friendly to cars, but it can’t be both.” Boulder’s congestion reduction objective is in conflict with this essential truth.

Fortunately, congestion regulates itself if we let it. Congestion will persuade some to drive at non-rush hour times, or take less congested routes, or travel by walking, bicycling, or transit. Congestion therefore does not inexorably lead to gridlock if we don’t widen a road or intersection, because some car trips (the “lower-value” trips) do not occur. Many of those discouraged trips are foregone because of the “time tax” imposed by the congestion.

But widening a road (or, in Boulder’s case, adding a second left-turn lane) short-circuits this self-regulation. A widened road or a double-left turn lane intersection induces new car trips because the road/intersection is now (briefly) less congested. The lower congestion encourages formerly discouraged car trips to now use the route during rush hour. Car trips that used different routes to avoid the congestion now converge back on the less congested route. And some get back in their cars after a period of walking, bicycling or using transit.

The process is very much like the infamous Soviet bread lines. The Soviets wanted to reduce the extremely long lines of people waiting for free bread. Their counterproductive “solution” was to make more free bread. But more free bread just induced more people to line up for bread. Likewise, the conventional American solution to traffic congestion is to make more free space for cars (widening the road or adding a second turn lane). The result is the same, as the bigger roads and intersections inevitably induce more car trips on those routes. The efficient and effective solution, as any first-year economics student will point out, is to NOT make more free bread or wider, free-to-use roads or second turn lanes. The solution is to price the bread and the car routes so that they are used more efficiently (and not wastefully by low-value bread consumers or car travelers). Or, to let a moderate level of congestion discourage low-value rush hour trips.

Given all of this, widening a road or adding a second left-turn lane to solve congestion is like loosening one’s belt to solve obesity. Similarly, despite conventional wisdom, car traffic does not behave like water flowing through a pipe (i.e., flowing easier if the pipe is expanded in size). Car traffic, instead, behaves like a gas. It expands to fill the available, increased volume provided.

Boulder’s Overriding Objectives

Boulder (and PLAN-Boulder County) has outlined key community objectives.

1. One is higher quality of life and more happiness. But counterproductively, happy cars lower quality of life due to clashing values and needs.

2. Another objective is for a more compact, walkable, vibrant city. Unfortunately, over-emphasizing cars means more sprawl.

3. An objective that is much talked about in the area is more affordability. By inducing more car dependence via easier car travel, the congestion reduction objective undermines the affordability objective by making Boulder less affordable (more on that later).

4. Given the growing concern for global warming, Boulder is placing more emphasis on reducing greenhouse gas emissions. Easing traffic congestion, however, induces new car traffic, which increases car emissions.

5. Boulder and PLAN-Boulder County seek more travel (and lifestyle) choices. But the congestion reduction objective in Boulder’s plan is again undercutting other objectives because it leads to bigger car infrastructure (bigger roads and intersections), thereby reducing travel and lifestyle choices.

As shown above, then, Boulder’s congestion reduction objective undermines each of these five essential community objectives.

Oops.

Conventional methods of reducing congestion include wider roads, bigger parking lots, one-way streets, and huge intersections. These tactics are a “win-lose” proposition. While they can reduce congestion (briefly), they also cause a loss of human scale and charm; a loss of social gathering; sprawling dispersal; more car dependence and less bicycling, walking, transit; higher taxes; economic woes (for government, shops and households); a decline in public health; and more air pollution.

By striking contrast, other less commonly used but much more beneficial transportation tactics are “win-win” propositions. Some of these tactics include road diets, designing streets for slower speeds, and designing for travel and lifestyle choices. They can result in:

• More parking spaces
• More civic pride (induced by human scale)
• More social gathering
• A more compact and vibrant community
• Less car dependence and more bicycling, walking, and transit
• Lower taxes
• Economic health (for both government and households)
• Improvement in public health
• Less air pollution

If we can’t get rid of congestion, what CAN we do? We can create alternatives so that those who are unwilling to tolerate the congestion can find ways to avoid it. Congestion can be better avoided if we create more housing near jobs, shops, and culture. Doing this allows more people to have better, more feasible ways to travel without a car. We can also create more travel routes, so that the congested routes are not the only routes to our destinations. Some of us can be given more flexible work schedules to shift our work hours away from rush hour. And some of us can be given increased opportunities to telecommute (work from home).

How Can We Design Transportation to Achieve a Better Destiny?

An important way to start Boulder on a better destiny for the city is to revisit the “No more than 20 percent congested road miles” objective in the Boulder transportation master plan. Some possibilities: adopt a “level of service standard” not for cars, but for bicycle, walking and transit travel; “Level of service” standards for cars is becoming outdated because it is being increasingly seen as counterproductive, as described earlier. Other alternatives to the “congestion” objective is to have a target of controlling or reducing vehicle miles traveled (VMT) community-wide; or set a goal of minimizing trip generation by individual new developments in the city.

Another option is to keep the congestion objective, but create “exception” areas where the congestion rule does not apply. Those exception areas would be places where Boulder seeks to encourage new development.

Boulder needs to ensure that the community land development and transportation design tactics are appropriately calibrated within each “transect zone” of the community. (The “transect” principle identifies a transition from urban to rural, whereby the town center is more compact, formal, low-speed, and walkable; the suburbs are more dispersed, informal, higher-speed, and drivable; and the rural areas most remote from the town center are more intended for a farming and conservation lifestyle. Development regulations and transportation designs are calibrated so that the differing lifestyle and travel objectives of each zone are best achieved.) However, the difficulty with the transect principle in places like Boulder is that the demand for compact, walkable lifestyles and travel choices is much higher than the supply of such places in Boulder. There is, in other words, a large mismatch. By contrast, the supply of suburban, drivable areas is quite high. To correct this imbalance, Boulder should strive to create a larger supply of compact, walkable places similar to Pearl Street Mall, the Boulder town center, and even the CU campus. Opportunities now being discussed are the creation of new, compact villages and town centers at places such as street intersections outside of the Boulder town center.

As an aside, the community transect concept informs us that in the town center, “more is better.” That is, the lifestyle being sought in the community center is one where more shops, more offices, and more housing enhances the lifestyle, as this more proximate, mixed, compact layout of land uses provides the thriving, sociable, convenient, vibrant, 24-hour ambience that many seeking the walkable lifestyle want more of.

By contrast, in the more drivable suburbs, “more is less.” That is, the drivable lifestyle is enhanced in quality when there is less density, less development, more dispersal, and more isolation of houses from shops and offices. The ambience generally desired is more quiet and private.

While town center housing is increasingly expensive compared to the suburbs—particularly in cities such as Boulder—such in-town housing provides significant cost savings for transportation. Because such a housing location provides so many travel choices beyond car travel, many households find they can own two cars instead of three or one car instead of two. And each car that a household can “shed” due to the richness of travel choices provides more household income that can be directed to housing expenses such as a mortgage or rent. Today, the average car costs about $9,000 per year to own and operate. In places that are compact and walkable, that $9,000 (or $18,000) per year can be devoted to housing, thereby improving affordability.

In addition to providing for the full range of housing and travel choices, Boulder can better achieve its objectives through road diets, where travel lanes are removed and more space is provided for such things as bike lanes or sidewalks or transit. Road diets are increasingly used throughout the nation—particularly converting roads from four lanes to three. Up to about 25,000 vehicle trips per day on the road, a road that is “dieted” to, say, three lanes carries about as much traffic as a four-lane road. This is mostly due to the fact that the inside lanes of a four-laner frequently must act as turn lanes for cars waiting to make a left turn. Four-lane roads are less desirable than three-lane streets because they induce more car trips and reduce bicycle, walking and transit trips. Compared to three-lane streets, four-lane roads result in more speeding traffic. As a result, four-laners create a higher crash rate than three-lane streets. Finally, because the three-lane street is more human-scaled, pleasant, lower-speed, and thereby place-making, a three-lane street is better than a four-lane street for shops. The three-lane street becomes a place to drive TO, rather than drive THROUGH (as is the case with a four-lane street).

If Boulder seeks to be transformative with transportation—that is, if the city seeks to significantly shift car trips to walking, bicycling and transit trips (rather than the relatively modest shifts the city has achieved in the past)—it must recognize that it is NOT about providing more bike paths, sidewalks, or transit service. It is about taking away road and parking space from cars, and taking away subsidies for car travel.

Another transportation tactic Boulder should pursue to achieve a better destiny is to unbundle the price of parking from the price of housing. People who own less (or no) cars should have the choice of opting for more affordable housing—housing that does not include the very expensive cost of provided parking. Currently, little or no housing in Boulder provides the buyer or renter the option of having lower cost housing payments by choosing not to pay for parking. Particularly in a place like Boulder, where land values are so high, even housing intended to be relatively affordable is more costly than it needs to be because the land needed for parking adds a large cost to the housing price. Indeed, by requiring the home buyer or renter to pay more for parking, bundled parking price creates a financial incentive for owning and using more cars than would have otherwise been the case.

Boulder should also strive to provide parking more efficiently by pricing more parking. Too much parking in Boulder is both abundant and free. Less parking would be needed in the city (which would make the city more affordable, by the way) if it were efficiently priced.  Donald Shoup recommends, for example, that parking meters be priced to ensure that in general, 2 or 3 parking spaces will be vacant on each block.

Efficient parking methods that could be used more often in Boulder include allowing shops and offices and churches to share their parking. This opportunity is particularly available when different land uses (say churches and shops) don’t share the same hours of operation. Again, sharing more parking reduces the amount of parking needed in the city, which makes the city more compact, walkable, enjoyable and active.

Like shared parking, leased parking allows for a reduction in parking needed. If Boulder, for example, owns a parking garage, some of the spaces can be leased to nearby offices, shops, or housing so that those particular land uses do not need to create their own parking.

Finally, a relatively easy and quick way for Boulder to beneficially reform and make more efficient its parking is to revise its parking regulations so that “minimum parking” is converted to “MAXIMUM parking.” Minimum parking rules, required throughout Boulder, are the conventional and increasingly outmoded way to regulate parking. They tell the developer that at least “X” amount of parking spaces must be provided for every “Y” square feet of building. This rule almost always requires the developer to provide excessive, very expensive parking, in large part because it is based on “worst case scenario” parking “needs.” That is, sufficient parking must be provided so that there will be enough on the busiest single day of the year (often the weekend after Thanksgiving). Such a provision means that for the other 364 days of the year, a large number of parking spaces sit empty, a very costly proposition.

In contrast, maximum parking rules tell the developer that there is an upper limit to the number of spaces that can be provided. This works much better for the community and the business because the business is better able to choose how much parking it needs and can finance. Since financial institutions that provide financing for new developments typically require the developer to provide the conventional (read: excessive) amounts of parking as a condition for obtaining a development loan, the big danger for communities in nearly all cases is that TOO MUCH parking will be provided rather than too little. The result of setting “maximum” instead of “minimum” parking rules is that excessive, worst case scenario parking developments become much more rare.

The reform of parking is easy: simply convert the existing minimum parking specifications to maximum parking standards (“at least 3 spaces per 1,000 square feet” becomes “no more than 3 spaces per 1,000 square feet). An incremental approach to this conversion is to apply maximum parking rules in those places that are already rich in travel choices, such as the Boulder town center.

Again, what will Boulder’s destiny be? As the preceding discussion sought to demonstrate, much of that destiny will be shaped by transportation decisions.

Will destiny be shaped by striving for happy people and happy places for people? Or will it be shaped by opting for the conventional, downwardly-spiraling effort of seeking easy car travel (and thereby unpleasant places where only a car can be happy – such as huge highways or parking lots)?

Will Boulder, in other words, retain or otherwise promote place-less conventional shopping centers full of deadening parking, car-only travel, lack of human interaction, and isolation? Or will the city move away from car-happy objectives such as the congestion reduction policy, and instead move toward a people-friendly future rich in sociability, pride in community, travel choices, sustainability, place-making and human scale?

An example of these contrasting destinies is Pearl Street. West Pearl features the charm and human scale we built historically. West Pearl Street exemplifies a lovable, walkable, calm, safe and inviting ambience where car speeds are slower, the street is more narrow, and the shops—by being pulled up to the streetside sidewalk—help form a comfortable sense of enclosure that activates the street and feels comfortable to walk. The shops tend to be smaller—more neighborhood-scaled.

East Pearl Street near 28^th Street is starkly different. There, the street is a “stroad,” because it is an overly wide road that should be a more narrow, lower-speed street. Shops are pulled back long distances from the street. The street here is fronted not by interesting shop fronts but enormous seas of asphalt parking. The layout is car-scaled. The setting is hostile, unpleasant, unsafe, stressful and uninviting. The shops tend to be “Big Box” retail, and serve a regional “consumershed.” There is “no there there.”

East Pearl Street was built more recently by professional planners and engineers who have advanced degrees that far exceed the professionalism and education of those who designed the more lovable West Pearl Street. Where has the charm gone? Why have our streets become less pleasant in more recent years (by better trained and better educated designers, I might add)? Is it perhaps related to our more expensive and sophisticated efforts to ease car traffic and reduce congestion?

There is an inverse relationship between congestion and such measures as vehicle miles traveled and gas consumption. At the community level—despite the conventional wisdom—as congestion increases, vehicle miles traveled, gas consumption, air emissions DECREASE. And as conventional efforts to reduce congestion intensify, quality of life and sustainability also decrease.

Again, is Boulder aligning itself with the Sprawl Lobby by maintaining an objective of easing traffic flow – by striving to reduce congestion?

On Controlling Size

David Mohney reminds us that the first task of the urban designer is to control size. This not only pertains to the essential need to keep streets, building setbacks, and community dispersal modest in size. It also pertains to the highly important need to insist on controlling the size of service and delivery trucks. Over-sized trucks in Boulder lead the city down a ruinous path, as street and intersection dimensions are typically driven by the “design vehicle.” When trucks are relatively large, excessive truck size becomes the “design vehicle” which ends up driving the dimensions of city streets. A healthy city should be designed for human scale and safety, not for the needs of huge trucks. Indeed, because motor vehicles consume so much space, a sign of a healthy, well-designed community is that drivers of vehicles should feel inconvenienced. If driving vehicles feels comfortable, it is a signal that we have over-designed streets and allocated such excessive spaces that we have lost human scale and safety.

A proposal for human-scaled streets: in Boulder’s town center, no street should be larger than three lanes in size. Outside the town center, no street should be larger than five lanes in size. Anything more exceeds the human scaling needed for a pleasant, safe, sustainable community.

It is time to return to the timeless tradition of designing to make people happy, not cars. Boulder needs to start by revisiting its congestion reduction objective, putting a number of its roads on a “road diet,” and taking steps to make the provision of parking more efficient and conducive to a healthy city.

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 More about the author

 Mr. Nozzi was a senior planner for Gainesville FL for 20 years, and wrote that city’s long-range transportation plan. He also administered Boulder’s growth rate control law in the mid-90s. He is currently a member of the Boulder Transportation Advisory Board.

 Studies Demonstrating Induced Traffic and Car Emission Increases

Below is a sampling of references to studies describing how new car trips are induced by easier car travel, and how car emissions increase as a result.

http://www.sierraclub.org/sprawl/articles/hwyemis.asp

http://www.vtpi.org/gentraf.pdf

http://en.wikipedia.org/wiki/Induced_demand

https://walkablestreets.wordpress.com/1993/04/18/does-free-flowing-car-traffic-reduce-fuel-consumption-and-air-pollution/

TØI (2009), Does Road Improvement Decrease Greenhouse Gas Emissions?, Institute of Transport Economics (TØI), Norwegian Centre for Transport Research (www.toi.no); summary at www.toi.no/getfile.php/Publikasjoner/T%D8I%20rapporter/2009/1027-2009/Sum-1027-2009.pdf

Robert Noland and Mohammed A. Quddus (2006), “Flow Improvements and Vehicle Emissions:

Effects of Trip Generation and Emission Control Technology,” Transportation Research D, Vol. 11 (www.elsevier.com/locate/trd), pp. 1-14; also see

www.cts.cv.ic.ac.uk/documents/publications/iccts00249.pdf

Clark Williams-Derry (2007), Increases In Greenhouse-Gas Emissions From Highway-Widening Projects, Sightline Institute (www.sightline.org); at

www.sightline.org/research/energy/res_pubs/analysis-ghg-roads

TRB (1995), Expanding Metropolitan Highways: Implications for Air Quality and Energy Use,

Committee for Study of Impacts of Highway Capacity Improvements on Air Quality and Energy

Consumption, Transportation Research Board, Special Report #345 (www.trb.org)

D. Shefer & P. Rietvald (1997), “Congestion and Safety on Highways: Towards an Analytical Model,” Urban Studies, Vol. 34, No. 4, pp. 679-692.

Alison Cassady, Tony Dutzik and Emily Figdor (2004). More Highways, More Pollution: Road Building and Air Pollution in America’s Cities, U.S. PIRG Education Fund (www.uspirg.org).

http://www.opr.ca.gov/docs/PreliminaryEvaluationTransportationMetrics.pdf

Many Cities Changing One-Way Streets Back

By Melanie Eversley, USA TODAY

12/20/06

More traffic will be coming to downtown Danville, Ill. — and that’s how Danville wants it. The city of 33,000 is converting some of its longtime one-way streets back to two-way thoroughfares. City officials hope the change will make it easier for customers to reach downtown stores and shop in them.

“The driving force behind it is economic development,” says city engineer David Schnelle, who expects to reprogram signals, change pavement markings and change signs by November 2007.

He says motorists tend to drive faster on one-way streets and go past their destinations, then lose time and patience backtracking.

Danville is one of hundreds of cities — from Berkeley, Calif., to Charleston, S.C. — switching one-way streets to two-way to improve commerce downtown, according to the American Planning Association in Chicago. The trend got rolling in the early 1990s and has expanded this year to bigger cities such as Miami, Dallas and Minneapolis. It’s part of the reinvention of former industrial cities, which are converting empty factories into loft housing and trying to convince suburbanites that downtowns are livable.

“There’s a lot of emphasis now on taming the automobile and emphasizing walking and biking. It’s all part of creating a place that people want to be,” says Marya Morris of the American Planning Association. “The bigger pieces are the major downtown housing booms and having things for people to do after 5.”

The boom in one-way streets began with the Cold War in the 1950s, when cities planned quick routes out of town for evacuation in case of nuclear attack, says John Norquist, one of the first vocal advocates of two-way-street conversion. Norquist was mayor of Milwaukee from 1988 to 2003 and now runs the Congress for the New Urbanism, which promotes the revitalization of cities.

The growth of the suburbs contributed, too, as cities smoothed the route home from work, says Neal Hawkins, associate director for traffic operations at the Iowa State University Center for Transportation Research and Education. Now, though, there are more jobs in the suburbs, more entertainment downtown, and drivers go in all directions.

They drive less efficiently on two-way streets, according to the Thoreau Institute, an environmental advocacy group in Oregon. The slower stop-and-go traffic means cars pollute more, the institute says.

In Danville, 170 miles south of Chicago, two-way streets are meant to speed an economic revival after 15 years of plant closings left downtown streets quiet. The city set up a small-business loan program to attract stores and restaurants.

Now Danville wants to make it easier for customers to find them, especially the shops on Vermilion Street.

Marie Pribble, co-owner of the Java Hut coffee shop and cafe, looks forward to the change. “The slower people go, the more likely they are to pay attention to your business or your storefront, and the more likely they are to stop in,” she says.

Norquist was one of the first mayors to promote more two-way streets. He led a campaign to convert several downtown Milwaukee streets back to two-way. He says the increased traffic means that neighborhoods flourish: “I think people started to realize that the city was more important than the road that runs through it.”

 

Road Widening Worsens Conditions for Atlanta

By Brian Gist, Jim Grode

For the Atlanta Journal-Constitution

Published on: 11/03/06

 

Atlantans hardly need a group of researchers to tell them that traffic in the region is a mess. But a recently released study of transportation patterns shows just how bad it is.

Our average commute time is 31.2 minutes, five minutes longer than in 1990, the highest increase in the country. We have three of the worst bottlenecks in the country. Less than 4 percent of Atlantans take transit to work.

So, not only does Atlanta have some of the worst traffic in the country, but also our attempts to build our way out of congestion are failing.

Urban planners say traffic congestion can’t be eliminated simply by building roads. Atlanta’s decades-long love affair with more and bigger highways has proved them correct. Wider highways increase capacity, which encourages sprawl, generating more traffic, and pretty soon those wider highways are clogged with traffic.

The solution to traffic congestion in a modern urban center such as Atlanta lies in transportation alternatives, not more highways. We must focus on efforts that reduce the number of vehicles on Atlanta’s roads, increase access to and coverage of the mass transit network and make land-use decisions that allow people to live near transit, jobs and shopping. Building smarter rather than larger will also help relieve Atlanta’s air quality problems by reducing tailpipe pollution.

The study, Commuting in America III, by the Transportation Research Board comes as state and federal transportation agencies are considering a slate of major new projects intended to alleviate traffic congestion in metro Atlanta, such as expanding I-75 and I-575 in Cobb and Cherokee counties. Several scenarios are proposed for the project, some of which include positive elements such as increased use of bus rapid transit and new transit stations to serve these buses.

But one serious failing in the expansion proposal is the lack of rail-based projects. The stability provided by rail infrastructure can fundamentally change metro Atlanta’s land-use patterns, allowing the region to proactively guide growth, rather than react to it. As long as Atlanta builds roads rather than rails, we will always be a step, or more, behind our transportation problems.

Even more troubling, however, is that the scenarios call for adding as many as eight lanes to I-75, creating 23-lane-wide portions of concrete — wider than the length of a football field.

These new lanes will do little or nothing to reduce the number of vehicles on the road. And in a twist that shows just how foolish our transportation planning has become, the new lanes will end at the junction of I-75 and I-285, one of the worst traffic bottlenecks in the country, as the commuting study identified. All the vehicles in the new lanes will have to rejoin the existing lanes, making the bottleneck even worse. Further, the proposal also calls for between four and six new lanes elsewhere in the 75/575 project area. None of these additional lanes will solve the congestion problem. They will just relocate it, and probably make it worse.

Here’s another wrinkle: Georgia is facing a massive deficit in its transportation budget. According to the Statewide Transportation Plan, currently proposed projects will cost almost double what the state has to spend. The last thing we should be doing is spending our scarce transportation dollars on highway projects that will all too quickly worsen our traffic crisis and air quality.

The I-75/575 proposal, and all projects intended to avoid gridlock, must be given a hard look to ensure they will actually reduce congestion and not perpetuate the cycle of unnecessary highway construction that created Atlanta’s traffic crisis in the first place.

These projects frame the critical question that will determine Atlanta’s transportation future: Will we simply continue to build larger highways, or will we realize that Atlanta’s congestion problem can only be solved by building smarter?

The public will have a critical opportunity to weigh in on the I-75/ I-575 proposal when the draft environmental study is released this year.

Atlantans must demand that the transportation agencies charged with making these decisions stop building bigger and more highways, and start building a smarter transportation future. Let’s not find out 10 years from now in another study that we have added yet another five minutes or more to our commute.

> Brian Gist and Jim Grode are attorneys in the Atlanta office of the Southern Environmental Law Center.

 

Around DC, a Cheaper House May Cost You

Longer Commutes Outweigh Savings of Living in Outer Suburbs, Study Shows

By Eric M. Weiss

Washington Post Staff Writer

Thursday, October 12, 2006

One of the lures of the outer suburbs is more house — maybe even one with a big yard — for less money. But a new study shows that the savings are illusory: The costs of longer commutes are so high that they can outweigh the cheaper mortgage payments.

A study of Washington and 27 other metropolitan areas by the Center for Housing Policy found that the costs of one-way commutes of as little as 12 to 15 miles — roughly the distance between Gaithersburg and Bethesda — cancel any savings on lower-priced outer-suburban homes.

“If you save $40,000 to $50,000 by not buying that house in Montgomery County but expand your commute by an extra 30 miles a day, you can certainly see how that new house could not end up being the deal you thought it was, especially if gas is at $3 a gallon,” said Lon Anderson, spokesman for AAA Mid-Atlantic. “But because of the exorbitant cost of housing closer in to [the District], they don’t have a choice if they want to live with their families in a home they can afford.”

Barbara J. Lipman, an author of the study, said that people tend to focus on all the zeroes that differentiate the price of a closer-in house from one in the outer suburbs, but they don’t realize how much they’re spending on commuting costs, such as gas, tires and insurance.

“Even if you save a couple of hundred dollars a month on your mortgage, it doesn’t nearly outweigh the costs of the cars you are driving,” she said.

The average cost of owning a 2006 Toyota Camry and driving it 15,000 miles a year with gas at $2.40 a gallon works out to $7,967 a year, according to AAA.

Higher gas prices put such a strain on Hannah and David Lynch’s budget that they decided to carpool instead of driving separately to their jobs from their Sterling home, even though she works in the District and he works in Baileys Crossroads.

Moving closer to their jobs is out, Hannah said, because “there is no way we could move into an equivalent three-bedroom house for the same amount,” she said. “We don’t want to downsize and give up a yard, for instance.”

Still, the frustrations of her 90-minute one-way commute can sometimes rankle, she said, “especially when there’s a stupidity delay on the [Dulles] Toll Road. It’s a trade-off.”

The study also found that a lack of affordable housing near job centers in the Washington area and elsewhere forces low- to moderate-income families to live in outer suburbs where transportation options are few and costs are high.

Families in the Washington area that earn $20,000 to $50,000 a year spend nearly a third of their income on housing, a figure exceeded only in the San Francisco area, the study says.

“We do have central-city job growth, but in Washington and other places, jobs are growing faster in the suburbs, and the population generally is suburbanizing farther and farther out,” said Lipman, who works for the Center for Housing Policy, which is a research arm of the National Housing Conference, a District-based, nonpartisan, nonprofit organization that advocates for affordable housing.

Of the 20 fastest-growing counties in the United States, 15 are located 30 miles or more from urban centers, including Loudoun and Stafford counties, Lipman said.

Lipman said many communities have identified a lack of affordable housing, traffic-clogged roads and longer commutes as critical issues but have not linked them. “One thing this study shows is the need to have regional solutions about both housing and transportation,” she said.

The study found that most people in the outer suburbs pay so much for transportation not just because of long commutes but also because they have to use their cars for nearly every errand and trip.

Lipman also said many of the trends will accelerate. The study noted that 62.1 percent of the U.S. metropolitan population lived in the suburbs in 1996, up from 55.1 percent in 1970.

And although the median national household income has risen 10.3 percent from 2000 to 2005, it has been outpaced by housing costs that have gone up 15.4 percent and transportation costs that have risen 13.4 percent over the same period. Gas prices, for instance, have been rising steadily over the past four years, more than doubling from $1.42 a gallon in June 2002 to $2.86 a gallon this past June.

Stewart Schwartz, executive director of the Coalition for Smarter Growth, said the data highlight a disconnect between where people live and work. Those with the highest commuting costs generally live on the eastern side of Washington, while many of the jobs are on the northern and western sides.

“A three-car family puts a lot of money into depreciating assets, instead of into mortgages and college educations,” he said.

 

The Merits of New Urbanism

By Dom Nozzi, AICP

The standards and principles of new urbanism are designed to make areas more livable, more vibrant, and more people-oriented, and to build community pride in the city and the work of its developers.

The people-oriented, traditional areas of the city share a number of desirable characteristics that provide us with many benefits. We should strive to preserve, celebrate, encourage and emulate how these areas are designed because of such benefits. For example, a traditionally designed city provides the following benefits:

Gives people without access to a car, such as children, the elderly, and the disabled, more safety and independence in their world.

Enhances urban livability, which reduces the desire to flee to the suburbs, which, in turn, reduces the pressure for costly sprawl and strip commercial development.

Substantially reduces government and household costs — especially because of the enormous savings in the building and maintaining of road infrastructure, and the purchase and maintenance of cars.

Reduces the need for travel.

Helps retain historic structures instead of replacing them with parking or large suburban retail “boxes””

Features streets designed to slow traffic. It increases travel choices and reduces the length and number of vehicle trips.

Makes neighborhoods more memorable and dignified.

Contains structures built for permanence, instead of structures designed, as too many contemporary structures are, for a short-term “throw-away” life.

Integrates income groups by mixing housing types and providing a public realm available to all incomes.

Makes walking feel more enjoyable.

Is not characterized as much by strip commercial visual blight.

Increases citizen access to culture.

Creates a good environment for smaller, locally-owned businesses to become established and to operate in.

Puts “eyes on the street” and promotes “citizen surveillance” of public places where citizens watch over their collective security, crime is reduced, as are public law enforcement costs.

Stabilizes, reinforces the identity of, and improves the value of nearby older neighborhoods.

Preserves and promotes community character.

Promotes neighborhood and community self-sufficiency and, therefore, sustainabilty.

Reduces per capita gasoline consumption and air pollution.

Coupled with regulations that are designed to promote and preserve its features, restores the traditional citizen hope and expectation for a better future with each new development in the city, and, in so doing, reduces the extreme polarization between developers and neighborhoods.

Provides affordable housing options.

Creates a sense of place, a sense of community, a sense of belonging and restores civic pride and place-based loyalty.

Strikes a balance between the needs of the car and the needs of the pedestrian. It creates a pedestrian ambiance and interesting pedestrian features, and makes the pedestrian feel safe, convenienced, and comfortable.

Creates a good environment for smaller, locally-owned businesses to become established and to operate in.

Increases transit viability, primarily through density, access, traffic calming, community-serving facilities, compactness, mixed use and pedestrian amenities.

Currently, developers are often reviled and their developments feared. This is manifested in the contemporary epidemic of NIMBYs (not in my backyard), NIMTOOs (not in my term of office), BANANAs (build absolutely nothing anywhere near anything), and NOPEs (not on planet earth). Largely, these attitudes have emerged because since WWII, developers and cities have sought to make cars instead of people happy.

Typically, American suburbs are characterized by this design. Suburban design features:

Large setbacks that are inconvenient for pedestrians and fail to define a comfortable public realm

Large parking lots in front of buildings

Large street blocks with no cross access or connecting streets

Buildings with their backs or sides turned toward the street. Instead of an entrance or windows, the pedestrian is confronted with blank walls, air compressors, dumpsters, and long walks to the building

Pedestrian-hostile features that are designed to promote car use, such as drive-throughs, single-use zoning, segregation of land uses, and “armoring” with fences and walls

To make Gainesville a safer, more livable place, and to increase citizen pride in its developments, the new urbanist standards are designed to primarily promote the health, safety, and welfare of pedestrians, while still accommodating the needs of the car. More specifically, the design is intended to make the pedestrian feel:

Safe and secure

Convenienced

Pleasant and comfortable

With enhanced safety, livability, civic pride, and visual appeal in these older parts of the city, the city will establish an important engine in job recruitment and a strengthened tax base. A downtown that adheres to these standards will be a city that provides an important incubator for new, entrepreneurial, locally-owned small businesses and entry-level job opportunities. A healthy downtown also protects the property values of surrounding residential areas.

Some Principles of New Urbanism

Build-To Line

Overly large setbacks are inconvenient and unpleasant for pedestrians. They are inconvenient because they can significantly increase walking distances from the public sidewalk. They are unpleasant because they prevent the pedestrian on the public sidewalk from enjoying the building details and the activity within the building. In addition, they prevent the building from contributing to an intimate, pleasant, comfortable street wall, which harms the sense of place and makes the pedestrian feel as if she or he is in “no man’s land.” Buildings pulled up to the street sidewalk have more of a human scale. The intent of a build-to line is to pull the building facade up to the street to abut the streetside sidewalk. By doing so, building facades along a block face will be aligned to form a street wall that frames the public realm, while retaining sufficient width for people to walk, and sufficient space to provide a formal landscape created by the shade of street trees. The street wall shapes the public realm to provide a sense of comfort and security for the public space.

Building Height of At Least Two Stories

“Low-slung” one-story buildings are more appropriate in low-density residential areas designed for motor vehicle travel. They reduce the density and intensity needed to make transit, walking, and bicycling viable, and typically are too low in profile to form a desirable, intimate, comfortable public realm with facing buildings across the street. They also reduce the opportunity to create mixed-use buildings containing, typically, both commercial and residential uses. Low-rise multi-story buildings two to five stories in height are an important component of the compact, walkable city. The building profile forms the desired street wall and the additional stories allow the establishment of the number of residents needed for a viable urban neighborhood.

Parking Located at the Rear or Side of Building Instead of in Front

Parking areas located in front of buildings are inconvenient and unpleasant for pedestrians. They are inconvenient because they significantly increase walking distances from the public sidewalk. They are unpleasant because they often make for hot expanses of areas to walk in, prevent the pedestrian on the public sidewalk from enjoying the building details and the activity within the building, and increase safety problems since pedestrians must dodge cars in the parking area. In addition, they prevent the building from contributing to an intimate, pleasant, comfortable street wall, which harms the sense of place and makes the pedestrian feel as if she or he is in “no man’s land.” Buildings pulled up to the street without intervening motor vehicle parking have more of a human scale.

Hidden Trash and Recycling Receptacles and Loading Docks

Trash and recycling receptacles and loading docks typically provide an unsightly appearance and an odor problem for pedestrians. In addition, improperly located and improperly screened receptacles and docks can cause noise problems for nearby land uses when the receptacles and packages are being loaded or unloaded. Therefore, they should be located as far from public sidewalks as possible and screened from view.

Sidewalks Sufficiently Wide and Aligned for Convenience

Sidewalks, when properly dimensioned and maintained, can provide the pedestrian with a pleasant, safe, and convenient place to walk. Sidewalks that are too narrow are inconvenient, especially in areas with large volumes of pedestrians, pedestrians walking side-by-side (which requires a minimum sidewalk width of five feet unobstructed), and people using wheelchairs. In addition, sidewalks that must wrap around large block faces are a serious impediment to pedestrian convenience.

Building Oriented to the Street, Instead of Turning Its Back to It

A successful commercial establishment is designed to provide convenience for customers by minimizing walking distances from public sidewalks and nearby buildings. Rear or side entrances, or entrances oriented toward a parking lot, make travel highly inconvenient for pedestrians and transit users. Such a design also cuts the building off from street life. In addition, a building with its main entrance directed away from the primary sidewalk and street “turns its back” to the public realm, reduces urban vibrancy, and is harmful to promoting street life. When a building is located at an intersection, the most convenient entrance is usually abutting the public sidewalks at the corner of the intersection. Often, the most convenient sidewalk is formally aligned diagonally and aligned straight to minimize walking distance.

Facade Treatment Creates Interest for Pedestrians

All building shall be designed to provide interest for pedestrians. Long expanses of blank walls tend to be boring and unattractive for the pedestrian. In addition, windows attract pedestrians, which act as a security system for the business. Buildings without such relief and interest tend to create a “massive scale”, and makes the public realm impersonal. Such an appearance is inconsistent with the “human-scaled” and pedestrian-oriented character of the a traditional area of a city, and inconsistent with a city intent to restore such character to the traditional city area.

Hidden Outdoor Mechanical Equipment

Outdoor mechanical equipment, such as heating or AC units, when improperly located on a site or improperly screened, can contribute to noise problems and create visual blight.

Formal Landscaping

In the traditional, pedestrian-oriented areas of a city, landscaping should be used both to soften the “hardness” of the urban area for the pedestrian, and make the pedestrian feel more comfortable by providing cooling, reducing glare and helping to form public spaces, “outdoor rooms,” and street corridor edges. Such formality of landscaping adds dignity to the traditional area of a city, instead of a chaotic one, thereby inspiring a sense of civic pride.

Properly Scaled Lighting

Lighting can often detract from the intimate, pleasant, romantic character a city seeks to promote in the traditional, pedestrian-oriented areas of a city. But lighting designed for cars tends to be not human-scaled. Lights on tall fixtures cause light pollution by casting light into areas not needed by pedestrians. In addition, the lights present a poor, bleached out atmosphere as the pedestrian views an area from afar, and hides the nighttime sky completely. A new urbanist, pedestrian-oriented street lighting design features shorter and more numerous light fixtures and structures.

Prohibited Auto-Oriented Uses

Certain uses are oriented toward or designed to attract motor vehicles, and therefore contribute to danger, visual blight, inconvenience, and lack of human scale for pedestrians. Therefore, such uses are not compatible with the a people-friendly downtown area.

Alleys

Alleys allow the developer to place garages, driveways, waste receptacles, and overhead utilities in a less conspicuous location away from the public street and therefore less likely to detract from the pedestrian ambiance of the neighborhood. Alleys also provide an additional location for emergency vehicles to gain access to a building, and a relatively safe place for children to play.

Front Porches

When they are set back a modest (“conversational”) distance from the sidewalk, porches allow persons to sit on their porch and interact and socialize with their neighbors. They therefore add safety (by putting “eyes on the street”) and friendliness to the street. As a result, porches contribute to an enjoyable walk by pedestrians in the neighborhood.

Narrow Streets

Narrow streets force cars and trucks to travel slowly through the neighborhood, which significantly contributes to neighborhood safety, low noise levels, low traffic volumes and, therefore neighborhood livability.

Mixed Housing Types

Mixed housing types provide the neighborhood with a mixed income environment, since the mixed types provide a range of housing affordability. Mixed housing types enable lower income workers to live within walking distance of their jobs, instead of creating traffic problems by being forced to commute by car to their jobs.

Transit Links

When a neighborhood contains — or is near — safe, pleasant, and convenient bus stops, a larger number of trips are made by bus, which reduces excessive neighborhood trips to and from the neighborhood by car. This provides more transportation choice, enhances neighborliness, and reduces household transportation costs (every car a household can shed saves the household the equivalent of the monthly home mortgage payment on a $51,000 house, at 10 percent interest).

On-Street Parking

Buffers pedestrians from vehicle travel. Narrows the street in order to slow traffic to a safer, more livable speed. Provides convenient parking locations for nearby businesses. Allows businesses and residences to reduce the amount of off-street, on-site parking, which reduces the “heat island” effect and enhances urban vibrancy by improving the public realm.

Mixed Use

Reduces trip distances to the point where walking, bicycling, and bus trips are much more feasible for a number of different types of trips. Adds to neighborhood and urban vibrancy by increasing the number of places people can meet — such as a pub, on the way to work or a civic event, a grocery store, a fitness center, etc. Provides children with more of an awareness of community land uses other than parks, residences, and schools.

Resessed Garages

Enhances the neighborhood walking environment for the pedestrian. Houses appear people-oriented and interesting to walk along, instead of sending a strong message that “a car lives here.”

Narrow, Smaller Lots

Provides a more compact, walkable arrangement of houses. Provides a more pleasing alignment of houses along the streetside sidewalk, which enhances civic pride in the neighborhood and makes the residential street seem more “cozy.” Blocks are reduced in size, which makes the neighborhood more walkable. Narrower lots increase the frequency of front doors along the street, which greatly enhances the vibrancy of the street. Houses appear to be associated in a neighborly way, instead of isolated and cocooned from the neighborhood. Smaller lots also make home ownership in such a subdivision more affordable. In addition, the higher, yet livable, density that smaller lots provide makes transit more viable.

Connected Streets

Makes walking, bicycling, and using the bus more feasible by significantly reducing trip distances and increasing the number of safe and pleasant routes for such travellers. Provides motorists and emergency service vehicles with more “real time” route choices. A route that is impeded or blocked can be avoided in favor of a clear route, which is not possible on a cul-de-sac. In combination with the fact that connected streets distribute vehicle trips more evenly, real time route choices on connected streets reduce congestion on collector or arterial roads. As a result of this distribution, there is little or no need for neighborhood-hostile collectors or arterials, which, because of the volume and speed of vehicle trips they carry, are unpleasant for residences to locate along.

Terminated Vistas

A concept in which a prominent building is placed at the “visual termination” of a street. Provides dignity and prominence to important civic buildings, such as post offices, libraries, city halls, churches, convention centers and performing arts centers. Sends the message that the building is an important place for the community. In addition, terminated vistas make walking more pleasant by giving the pedestrian a “goal” to walk toward. The walk therefore does not seem endless. It also provides an impressive view to strive to reach. Such vistas also make trips more memorable by helping to orient a person as to their location in the community.

Livable, higher densities

The conventional way in which we address land use conflicts is to put distance between conflicting activities, and minimize the number of dwelling units per acre. But this does little to encourage land users to reduce the damage they do to the environment. Also, by segregating uses, we increase the amount people have to travel by car, which itself reduces the quality of the urban and natural environment.

By contrast, the more compact, higher density “new urbanist” development reduces trip length; and makes bicycling, transit, and walking more viable. For these reasons, compact development generates about half as much vehicle travel as does sprawl development, making such a land use strategy one of the most effective in reducing auto dependence.

Minimum densities necessary for a viable bus system are approximately eight dwelling units per acre. Newman and Kenworthy indicate that only when densities exceed 7,000 to 8,000 persons per square mile (Gainesville’s density is currently 2,000 per square mile) do mixed land uses and shorter travel distances become predominant enough to significantly reduce auto dependence. These researchers note that a dramatic reduction in per capita gasoline consumption occurs when population density reaches 12 to 16 persons per acre. “Low density land use ensures almost total dependence on automobiles, enormous travel distances, no effective public transit, and little possibility of walking or [bi]cycling. Below five or six people per acre, a city almost ceases to exist, and requires enormous transportation energy to hold the scattered parts together.”

A recent study found that distance is the most widely cited reason for not walking more often, thereby showing the importance of compact development as a strategy to encourage walking. People living in high-density areas are much more likely to walk than those living in low-density suburbs, even when suburban trips are less than one mile (note that higher population densities seem to be more strongly correlated with higher walking rates than does a compact land use pattern). There also seems to be a correlation between the shorter commute distances associated with compact cities and higher bicycling rates. Compact, mixed-use development has been cited as much more likely than improved bicycle facilities, congestion fees, or fuel price increases to recruit motorists to bicycling.

Residential development that averages 14 dwelling units per acre requires half as much road mileage to serve vehicle trips than development at 3.5 dwelling units per acre. Another study found that for each doubling of residential density, vehicle miles traveled is reduced 30 percent. Thus, if the population of an area doubled due to infill development, vehicle miles traveled would probably increase by only 40 to 60 percent, rather than the 100 percent it would increase if the population increase occurred in dispersed suburbs.

A recent study has confirmed that the shift from car trips to transit and walking does not occur until certain job and housing densities are achieved. For work trips, the thresholds are 50 to 75 employees per gross acre, or 12 dwellings per net acre. For shopping trips, it is 75 employees per gross acre and 20 dwellings per acre.

One way to increase development densities is to remove land development policies that reduce development densities, such as minimum lot size zoning and minimum parking requirements.

Public service vehicles scaled small enough so that they do not dictate unsafe, wide streets

New urbanism encourages the use of public service and emergency vehicles (such as fire trucks) that are scaled to be compatible with neighborhoods. Increasingly, such vehicles are quite large, and their size often dictates rather wide streets and unsafe turning radii. Yet studies show that the dangers of such street design typically far outweigh the safety benefits that larger streets and turns will provide for emergency vehicles. In general, this is because the probability of traffic injury or death due to over-sized streets is much higher than the chance that injury or death would be averted because the emergency vehicle can shave a few seconds off of a trip. Therefore, smaller service vehicles can help a City keep average neighborhood vehicle speeds lower, make the streets safer and less noisy, make the neighborhood more walkable and, in general, more livable and sociable.

Streets and sidewalks straight, not curvilinear

Streets are more memorable and less disorienting when they are straight. They are more dignified, and can be terminated with a prominent vista. It is important that sidewalks be straight, since pedestrians have a strong desire to walk the distance that provides the minimum trip length. Curving sidewalks promote the creation of “cow paths,” as pedestrians take short cuts along their route. In general, curvilinear sidewalks are only appropriate when needed to avoid a large tree or other important physical feature, or in an area in which most pedestrians are walking strictly for optional recreation or exercise. This is generally not the case in an urban area, where almost all trips are utilitarian. Mostly, curving sidewalks are intended to improve the view of motorists driving along a road, and provide no important benefits for the pedestrian.

One-quarter mile walking distance

It is generally recognized that the convenient walking distance ranges up to one-quarter mile, or roughly a five- to ten minute walk. It is therefore important that for a neighborhood to be walkable, most homes should be within one-quarter mile of public parks, schools, civic buildings, retail, office, and various forms of culture. The one-quarter mile design yardstick also enhances the viability of transit.

Short, walkable block faces

In general, a neighborhood or commercial block face length should not exceed approximately 500 feet. Longer blocks tend to create inconvenient walking distances. When long blocks must be created, they should be shorted with cross-access walkways.

Ground-floor retail. Offices and residential above.

This form of mixed use enhances vibrancy and provides more affordable housing choices. It reduces the need for trips by car, since employees of the retail establishment can live above the shop. It is important that such “vertical mixing” of uses not place residential on the first floor, since it is disruptive for the residence when users of the office or retail must walk through the residence. It is also important that such mixed use include retail on the first floor so that more energy and interest is at the street level – -thereby benefiting pedestrians.

Eyes on the street. Citizen surveillance

Law enforcement agencies increasingly see the merits of citizen policing, in which citizens are able to watch out for their collective security. Such “eyes on the street” are promoted when buildings, windows, entrances and porches are near the street and sidewalk. Citizen surveillance is also promoted when the neighborhood or commercial areas are designed for regular, frequent pedestrian activity. Areas without pedestrian activity are areas where illegal, inappropriate, or unsafe behavior can occur more easily since there is no one to observe the deed and report it or intervene.

Diagonal usually the shortest walking distance

In general, the shortest walking distance is a diagonal route. Frequently, sidewalks are designed with right angle turns, which increases the walking distance and increases the likelihood of “cow path” shortcuts.

Centrally-located schools, parks, squares, civic w/in walking distance of most homes

When schools, parks, squares, and civic buildings are within easy walking distance of most residents, a sense of community and neighborliness is promoted, and vehicle trips are greatly reduced. If children are able to walk to school or a park, such areas can become social and recreational gathering places for students, because they are able to go to the school or return home on their own, as opposed to being required to leave when the bus leaves at the end of the class day.

Parks, squares and civic uses are more frequently used when residents have easy, non-vehicular access to them. When centrally located, they become the focal point of the neighborhood, and maximize the number of residences that are within walking distance.

Square street curbs

Square street curbs provide more safety for pedestrians, and provide a more attractive, urban appearance for the neighborhood.

Modest curb radius

A larger curb turning radius at an intersection or a parking area ingress and egress point allows vehicles to negotiate a turn rapidly, whereas a smaller radius forces a vehicle to slow down. Conventional traffic engineers often prefer a larger radius for vehicle convenience and curb protection, but such a radius makes life more inconvenient and dangerous for pedestrians. A larger radius also significantly increases the distance for crossing the street, which exposes the pedestrian to more danger from moving vehicles.

Note that large garbage trucks or delivery trucks or buses or fire trucks should not dictate the design of neighborhood curb radii. To do so is equivalent to obligating an architect to increase the size of the front door opening so that an overly large TV set can be brought into the house. No, the correct solution is to request that service and emergency vehicles be scaled for neighborhoods…

 

London’s Congestion Fee a Success

by Ken Livingstone

December 2004

The 2004 World Technology Winners and Finalists Winner: Ken Livingstone, Mayor, London, United Kingdom

Winner Commentary:

Central London had historically suffered from one of the worst levels of traffic congestion in the United Kingdom. Average traffic speeds were less than 10 miles per hour throughout much of the working day. This congestion was damaging London’s economy as people and goods spend unnecessary time in traffic rather than in productive activities. This congestion worsened the environment of London and made conditions unpleasant for other road users, in particular for walkers and cyclists. Something drastic needed to be done.

As new roads generate more traffic and in any case it is completely impractical to build new roads in such a densely developed area as London, a novel solution to rectifying this problem was required. As part of his 2000 election campaign the Mayor put forward his proposals for the central London congestion charge.

The scheme relies on people purchasing the charge, which can be obtained from shops and petrol stations, over the phone, via the web, 100 pay stations in car parks or by mobile phone text messaging. We also provide a fleet scheme used by 11,000 fleet vehicles per day. Their registration number is entered onto a database for that day. The scheme is enforced by cameras, which record the vehicle registration mark of all vehicles entering the zone. These are checked against the database of those that have paid, and if the registration mark is not included the owner of that vehicle will receive a fine. The technological issues in providing an efficient, reliable and integrated payment, monitoring and enforcement system were immense.

However, it was essential for this to work well, otherwise it could jeopardise the scheme itself, and given the world-wide scrutiny of this initiative, could lead other towns and cities deciding not to take forward similar schemes for their areas.

The scheme has been an enormous success. No other transport scheme has had such a positive impact on the traffic of a city. Detailed monitoring of its effects has been undertaken, with the key impacts being:

• An immediate 30% reduction in congestion within the charging zone, which has been sustained since
• An 18% reduction in traffic entering the zone, with the number of cars down by a third
• An encouragement of other modes of travel – both cycling and travel by bus is up by 20%
• A 60% reduction in delays to buses due to traffic impacts and a 30% improvement in overall bus reliability
• A 12% reduction in emissions of oxides of nitrogen (NOx) and fine particles (PM10)
• A reduction in road accidents (although too early to quantify)
• No detrimental traffic impact on the boundary road or surrounding areas
• On-street surveys show that people perceive the charge to have improved the environmental quality of the area

 

The lessons we learnt for the successful introduction of Congestion Charging

were:

* The political commitment from Ken Livingstone, the Mayor was essential.

* Consultation was genuine with a readiness to amend the scheme in the light of reasonable representations.

* Public transport, especially buses (as we did not control the trains), was greatly improved.

* *Traffic management was utilised to ensure the inner ring road around the zone ran freely.

* Residential parking restrictions were introduced where it was thought motorists might park just outside the zone.

* Extensive public information using most media (including local radio and

TV) to inform motorists of the practicalities for how to pay the charge and also to keep the public informed on progress. (We did not want the communication channels swamped on the first day with motorists asking basic questions).

* First class project management.

A key test of the scheme’s success is the degree to which the public support it. Ahead of the introduction of the charge there was a massive and sustained media campaign against the charge, although the balance of public opinion remained fairly even, with around 40% for and 40% against the charge. After 6 months of its operation almost 60% were in favour of the scheme compared with around 25% against. Probably the best test is that on 4 June 2004 Ken Livingstone was re-elected Mayor of London for another 4 years with more votes than previously and a margin of 11% above his main rival who threatened to abolish the Congestion Charge.

 

New York City is the Greenest City in America

GREEN MANHATTAN

Why New York is the greenest city in the U.S.

By David Owen

Published in The New Yorker

10/18/04

 

My wife and I got married right out of college, in 1978. We were young and naïve and unashamedly idealistic, and we decided to make our first home in a utopian environmentalist community in New York State. For seven years, we lived, quite contentedly, in circumstances that would strike most Americans as austere in the extreme: our living space measured just seven hundred square feet, and we didn’t have a dishwasher, a garbage disposal, a lawn, or a car. We did our grocery shopping on foot, and when we needed to travel longer distances we used public transportation. Because space at home was scarce, we seldom acquired new possessions of significant size. Our electric bills worked out to about a dollar a day.

The utopian community was Manhattan. (Our apartment was on Sixty-ninth Street, between Second and Third.) Most Americans, including most New Yorkers, think of New York City as an ecological nightmare, a wasteland of concrete and garbage and diesel fumes and traffic jams, but in comparison with the rest of America it’s a model of environmental responsibility. By the most significant measures, New York is the greenest community in the United States, and one of the greenest cities in the world. The most devastating damage humans have done to the environment has arisen from the heedless burning of fossil fuels, a category in which New Yorkers are practically prehistoric. The average Manhattanite consumes gasoline at a rate that the country as a whole hasn’t matched since the mid-nineteen-twenties, when the most widely owned car in the United States was the Ford Model T. Eighty-two per cent of Manhattan residents travel to work by public transit, by bicycle, or on foot. That’s ten times the rate for Americans in general, and eight times the rate for residents of Los Angeles County. New York City is more populous than all but eleven states; if it were granted statehood, it would rank 51st in per-capita energy use.

“Anyplace that has such tall buildings and heavy traffic is obviously an environmental disaster-except that it isn’t,” John Holtzclaw, a transportation consultant for the Sierra Club and the Natural Resources Defense Council, told me. “If New Yorkers lived at the typical American sprawl density of three households per residential acre, they would require many times as much land. They’d be driving cars, and they’d have huge lawns and be using pesticides and fertilizers on them, and then they’d be overwatering their lawns, so that runoff would go into streams.” The key to New York’s relative environmental benignity is its extreme compactness. Manhattan’s population density is more than eight hundred times that of the nation as a whole. Placing one and a half million people on a twenty-three-square-mile island sharply reduces their opportunities to be wasteful, and forces the majority to live in some of the most inherently energy efficient residential structures in the world: apartment buildings. It also frees huge tracts of land for the rest of America to sprawl into.

My wife and I had our first child in 1984. We had both grown up in suburbs, and we decided that we didn’t want to raise our tiny daughter in a huge city. Shortly after she learned to walk, we moved to a small town in northwestern Connecticut, about 90 miles north of midtown Manhattan. Our house, which was built in the late 1700s, is across a dirt road from a nature preserve and is shaded by tall white-pine trees. After big rains, we can hear a swollen creek rushing by at the bottom of the hill. Deer, wild turkeys, and the occasional black bear feed themselves in our yard. From the end of our driveway, I can walk several miles through woods to an abandoned nineteenth-century railway tunnel, while crossing only one paved road.

Yet our move was an ecological catastrophe. Our consumption of electricity went from roughly four thousand kilowatt-hours a year, toward the end of our time in New York, to almost thirty thousand kilowatt-hours in 2003-and our house doesn’t even have central air-conditioning. We bought a car shortly before we moved, and another one soon after we arrived, and a third one ten years later. (If you live in the country and don’t have a second car, you can’t retrieve your first car from the mechanic after it’s been repaired; the third car was the product of a mild midlife crisis, but soon evolved into a necessity.) My wife and I both work at home, but we manage to drive thirty thousand miles a year between us, mostly doing ordinary errands. Nearly everything we do away from our house requires a car trip. Renting a movie and later returning it, for example, consumes almost two gallons of gasoline, since the nearest Blockbuster is ten miles away and each transaction involves two round trips. When we lived in New York, heat escaping from our apartment helped to heat the apartment above ours; nowadays, many of the BTUs produced by our brand-new, extremely efficient oil-burning furnace leak through our 200-year-old roof and into the dazzling star-filled winter sky above.

When most Americans think about environmentalism, they picture wild, unspoiled landscapes-the earth before it was transmogrified by human habitation. New York City is one of the most thoroughly altered landscapes imaginable, an almost wholly artificial environment, in which the terrain’s primeval contours have long since been obliterated and most of the parts that resemble nature (the trees on side streets, the rocks in Central Park) are essentially decorations. Ecology-minded discussions of New York City often have a hopeless tone, and focus on ways in which the city might be made to seem somewhat less oppressively man-made: by increasing the area devoted to parks and greenery, by incorporating vegetation into buildings themselves, by reducing traffic congestion, by easing the intensity of development, by creating open space around structures. But most such changes would actually undermine the city’s extraordinary energy efficiency, which arises from the characteristics that make it surreally synthetic.

Because densely populated urban centers concentrate human activity, we think of them as pollution crisis zones. Calculated by the square foot, New York City generates more greenhouse gases, uses more energy, and produces more solid waste than most other American regions of comparable size. On a map depicting negative environmental impacts in relation to surface area, therefore, Manhattan would look like an intense hot spot, surrounded, at varying distances, by belts of deepening green.

If you plotted the same negative impacts by resident or by household, however, the color scheme would be reversed. My little town has about four thousand residents, spread over 38.7 thickly wooded square miles, and there are many places within our town limits from which no sign of settlement is visible in any direction. But if you moved eight million people like us, along with our dwellings and possessions and current rates of energy use, into a space the size of New York City, our profligacy would be impossible to miss, because you’d have to stack our houses and cars and garages and lawn tractors and swimming pools and septic tanks higher than skyscrapers. (Conversely, if you made all eight million New Yorkers live at the density of my town, they would require a space equivalent to the land area of the six New England states plus Delaware and New Jersey.)

Spreading people out increases the damage they do to the environment, while making the problems harder to see and to address.

Of course, living in densely populated urban centers has many drawbacks. Even wealthy New Yorkers live in spaces that would seem cramped to Americans living almost anywhere else. A well-to-do friend of mine who grew up in a town house in Greenwich Village thought of his upbringing as privileged until, in prep school, he visited a classmate from the suburbs and was staggered by the house, the lawn, the cars, and the swimming pool, and thought, with despair, You mean I could live like this? Manhattan is loud and dirty, and the subway is depressing, and the fumes from the cars and cabs and buses can make people sick. Presumably for environmental reasons, New York City has one of the highest childhood-asthma rates in the country, with an especially alarming concentration in East Harlem.

Nevertheless, barring an almost inconceivable reduction in the earth’s population, dense urban centers offer one of the few plausible remedies for some of the world’s most discouraging environmental ills. To borrow a term from the jargon of computer systems, dense cities are scalable, while sprawling suburbs are not. The environmental challenge we face, at the current stage of our assault on the world’s non-renewable resources, is not how to make our teeming cities more like the pristine countryside. The true challenge is how to make other settled places more like Manhattan. This notion has yet to be widely embraced, partly because it is counterintuitive, and partly because most Americans, including most environmentalists, tend to view cities the way Thomas Jefferson did, as “pestilential to the morals, the health, and the liberties of man.” New York is the place that’s fun to visit but you wouldn’t want to live there. What could it possibly teach anyone about being green?

New York’s example, admittedly, is difficult for others to imitate, because the city’s remarkable population density is the result not of conscientious planning but of a succession of serendipitous historical accidents. The most important of those accidents was geographic: New York arose on a smallish island rather than on the mainland edge of a river or a bay, and the surrounding water served as a physical constraint to outward expansion. Manhattan is like a typical seaport turned inside out-a city with a harbor around it, rather than a harbor with a city along its edge. Insularity gave Manhattan more shoreline per square mile than other ports, a major advantage in the days when one of the world’s main commercial activities was moving cargoes between ships. It also drove early development inward and upward.

A second lucky accident was that Manhattan’s street plan was created by merchants who were more interested in economic efficiency than in boulevards, parks, or empty spaces between buildings. The resulting crush of architecture is actually humanizing, because it brings the city’s commercial, cultural, and other offerings closer together, thereby increasing their accessibility-a point made forty-three years ago by the brilliantly iconoclastic urban thinker Jane Jacobs, in her landmark book “The Death and Life of Great American Cities.”

A third accident was the fact that by the early nineteen-hundreds most of Manhattan’s lines had been filled in to the point where not even Robert Moses could easily redraw them to accommodate the great destroyer of American urban life, the automobile. Henry Ford thought of cars as tools for liberating humanity from the wretchedness of cities, which he viewed with as much distaste as Jefferson did. In 1932, John Nolen, a prominent Harvard-educated urban planner and landscape architect, said, “The future city will be spread out, it will be regional, it will be the natural product of the automobile, the good road, electricity, the telephone, and the radio, combined with the growing desire to live a more natural, biological life under pleasanter and more natural conditions.” This is the idea behind suburbs, and it’s still seductive. But it’s also a prescription for sprawl and expressways and tremendous waste.

New York City’s obvious urban antithesis, in terms of density and automobile use, is metropolitan Los Angeles, whose metastatic outward growth has been virtually unimpeded by the lay of the land, whose early settlers came to the area partly out of a desire to create space between themselves and others, and whose main development began late enough to be shaped by the needs of cars. But a more telling counterexample is Washington, D.C., whose basic layout was conceived at roughly the same time as Manhattan’s, around the turn of the nineteenth century. The District of Columbia’s original plan was created by an eccentric French-born engineer and architect named Pierre-Charles L’Enfant, who befriended General Washington during the Revolutionary War and asked to be allowed to design the capital. Many of modern Washington’s most striking features are his: the broad, radial avenues; the hublike traffic circles; the sweeping public lawns and ceremonial spaces.

Washington is commonly viewed as the most intelligently beautiful-the most European-of large American cities. Ecologically, though, it’s a mess. L’Enfant’s expansive avenues were easily adapted to automobiles, and the low, widely separated buildings (whose height is limited by law) stretched the distance between destinations.

There are many pleasant places in Washington to go for a walk, but the city is difficult to get around on foot: the wide avenues are hard to cross, the traffic circles are like obstacle courses, and the grandiloquent empty spaces thwart pedestrians, by acting as what Jane Jacobs calls “border vacuums.” (One of Jacobs’s many arresting observations is that parks and other open spaces can reduce urban vitality, by creating dead ends that prevent people from moving freely between neighborhoods and by decreasing activity along their edges.) Many parts of Washington, furthermore, are relentlessly homogeneous. There are plenty of dignified public buildings on Constitution Avenue, for example, but good luck finding a dry cleaner, a Chinese restaurant, or a grocery store. The city’s horizontal, airy design has also pushed development into the surrounding countryside. The fastest growing county in the United States is Loudoun County, Virginia, at the rapidly receding western edge of the Washington metropolitan area.

The Sierra Club, an environmental organization that advocates the preservation of wilderness and wildlife, has a national campaign called Challenge to Sprawl. The aim of the program is to arrest the mindless conversion of undeveloped countryside into subdivisions, strip malls, and S.U.V.-clogged expressways. The Sierra Club’s Web site features a slide-show-like demonstration that illustrates how various sprawling suburban intersections could be transformed into far more appealing and energy-efficient developments by implementing a few modifications, among them widening the sidewalks and narrowing the streets, mixing residential and commercial uses, moving buildings closer together and closer to the edges of sidewalks (to make them more accessible to pedestrians and to increase local density), and adding public transportation-all fundamental elements of the widely touted anti-sprawl strategy known as Smart Growth.

In a recent telephone conversation with a Sierra Club representative involved in Challenge to Sprawl, I said that the organization’s anti-sprawl suggestions and the modified streetscapes in the slide show shared many significant features with Manhattan-whose most salient characteristics include wide sidewalks, narrow streets, mixed uses, densely packed buildings, and an extensive network of subways and buses. The representative hesitated, then said that I was essentially correct, although he would prefer that the program not be described in such terms, since emulating New York City would not be considered an appealing goal by most of the people whom the Sierra Club is trying to persuade.

An obvious way to reduce consumption of fossil fuels is to shift more people out of cars and into public transit. In many parts of the country, though, public transit has been stagnant or in decline for years. New York City’s Metropolitan Transportation Authority and Department of Transportation account for nearly a third of all the transit passenger miles traveled in the United States and for nearly four times as many passenger miles as the Washington Metropolitan Area Transit Authority and the Los Angeles County Metropolitan Transportation Authority combined.

New York City looks so little like other parts of America that urban planners and environmentalists tend to treat it as an exception rather than an example, and to act as though Manhattan occupied an idiosyncratic universe of its own. But the underlying principles apply everywhere. “The basic point,” Jeffrey Zupan, an economist with the Regional Planning Association, told me, “is that you need density to support public transit. In all cities, not just in New York, once you get above a certain density two things happen. First, you get less travel by mechanical means, which is another way of saying you get more people walking or biking; and, second, you get a decrease in the trips by auto and an increase in the trips by transit. That threshold tends to be around seven dwellings per acre. Once you cross that line, a bus company can put buses out there, because they know they’re going to have enough passengers to support a reasonable frequency of service.”

Phoenix is the sixth-largest city in the United States and one of the fastest growing among the top ten, yet its public transit system accounts for just one per cent of the passenger miles that New York City’s does. The reason is that Phoenix’s burgeoning population has spread so far across the desert-greater Phoenix, whose population is a little more than twice that of Manhattan, covers more than two hundred times as much land-that no transit system could conceivably serve it. And no amount of browbeating, public-service advertising, or federal spending can change that.

Cities, states, and the federal government often negate their own efforts to nurture public transit by simultaneously spending huge sums to make it easier for people to get around in cars. When a city’s automobile traffic becomes congested, the standard response has long been to provide additional capacity by building new roads or widening existing ones. This approach eventually makes the original problem worse, by generating what transportation planners call “induced traffic”: every mile of new highway lures passengers from public transit and other more efficient modes of travel, and makes it possible for residential and commercial development to spread even farther from urban centers. And adding public transit in the hope of reducing automobile congestion is as self-defeating as building new highways, because unclogging roads, if successful, just makes driving seem more attractive, and the roads fill up again. A better strategy would be to eliminate existing traffic lanes and parking spaces gradually, thereby forcing more drivers to use less environmentally damaging alternatives-in effect, “induced transit.”

One reason New Yorkers are the most dedicated transit users in America is that congestion on the city’s streets makes driving extraordinarily disagreeable. The average speed of crosstown traffic in Manhattan is little more than that of a brisk walker, and in midtown at certain times of the day the cars on the side streets move so slowly that they appear almost to be parked. Congestion like that urges drivers into the subways, and it makes life easier for pedestrians and bicycle riders by slowing cars to a point where they constitute less of a physical threat.

Even in New York City, the relationship between traffic and transit is not well understood. A number of the city’s most popular recent transportation-related projects and policy decisions may in the long run make the city a worse place to live in by luring passengers back into their cars and away from public transportation: the rebuilding and widening of the West Side Highway, the implementation of EZ-Pass on the city’s toll bridges, the decision not to impose tolls on the East River bridges, and the current renovation of the F.D.R. Drive (along with the federally funded $139 million Outboard Detour Roadway, which is intended to prevent users of the F.D.R. from being inconvenienced while the work is under way).

Public transit itself can be bad for the environment if it facilitates rather than discourages sprawl. The Washington Metropolitan Area Transit Authority is considering extensions to some of the most distant branches of its system, and those extensions, if built, will allow people to live even farther from the city’s center, creating new, non-dense suburbs where all other travel will be by automobile, much of it to malls and schools and gas stations that will be built to accommodate them. Transit is best for the environment when it helps to concentrate people in dense urban cores. Building the proposed Second Avenue subway line would be environmentally sound, because it would increase New Yorkers’ ability to live without cars; building a bullet train between Penn Station and the Catskills (for example) would not be sound, because it would enable the vast, fuel-squandering apparatus of suburbia to establish itself in a region that couldn’t support it otherwise.

On the afternoon of August 14, 2003, I was working in my office, on the third floor of my house, when the lights blinked, my window air-conditioner sputtered, and my computer’s backup battery kicked in briefly. This was the beginning of the great blackout of 2003, which halted electric service in parts of eight Northeastern and Midwestern states and in southeastern Canada. The immediate cause was eventually traced to Ohio, but public attention often focused on New York City, which had the largest concentration of affected power customers. Richard B. Miller, who resigned as the senior energy adviser for the city of New York six weeks before the blackout, reportedly over deep disagreements with the city’s energy policy, told me, “When I was with the city, I attended a conference on global warming where somebody said, ‘We really need to raise energy and electricity prices in New York City, so that people will consume less.’ And my response at that conference was ‘You know, if you’re talking about raising energy prices in New York City only, then you’re talking about something that’s really bad for the environment. If you make energy prices so expensive in the city that a business relocates from Manhattan to New Jersey, what you’re really talking about, in the simplest terms, is a business that’s moving from a subway stop to a parking lot. And which of those do you think is worse for the environment?’ ”

People who live in cities use only about half as much electricity as people who don’t, and people who live in New York City generally use less than the urban average. A truly enlightened energy policy would reward city dwellers and encourage others to follow their good example. Yet New York City residents pay more per kilowatt-hour than almost any other American electricity customers; taxes and other government charges, most of which are not enumerated on electricity bills, can constitute close to 20 percent of the cost of power for residential and commercial users in New York. Richard Miller, after leaving his job with New York City, went to work as a lawyer in Consolidated Edison’s regulatory affairs department, spurred by his thinking about the environment. He believes that state and local officials have historically taken unfair advantage of the fact that there is no political cost to attacking a big utility. Con Ed pays more than six hundred million dollars a year in property taxes, making it by far the city’s largest property-tax payer, and those charges inflate electric bills. Meanwhile, the cost of driving is kept artificially low. (Fifth Avenue and the West Side Highway don’t pay property taxes, for example.) “In addition,” Miller said, “the burden of improving the city’s air has fallen far more heavily on power plants, which contribute only a small percentage of New York City’s air pollution, than it has on cars-even though motor vehicles are a much bigger source.”

Last year, the National Building Museum, in Washington, D.C., held a show called “Big & Green: Toward Sustainable Architecture in the 21st Century.” A book of the same name was published in conjunction with the show, and on the book’s dust jacket was a photograph of 4 Times Square, also known as the Condé Nast Building, a 48-story glass-and-steel tower between Forty-second and Forty-third Streets, a few blocks west of Grand Central Terminal. (The New Yorker’s offices occupy two floors in the building.) When 4 Times Square was built, in 1999, it was considered a major breakthrough in urban development. As Daniel Kaplan, a principal of Fox & Fowle Architects, the firm that designed it, wrote in an article in Environmental Design & Construction in 1997, “When thinking of green architecture, one usually associates smaller scale,” and he cited as an example the headquarters of the Rocky Mountain Institute, a nonprofit environmental research and consulting firm based in Snowmass, Colorado. The R.M.I. building is a four-thousand-square-foot, super-insulated, passive solar structure with curving sixteen-inch-thick walls, set into a hillside about 15 miles north of Aspen. It was erected in the early eighties and serves partly as a showcase for green construction technology. (It is also the home of Amory Lovins, who is R.M.I.’s cofounder and chief executive officer.) R.M.I. contributed to the design of 4 Times Square, which has many innovative features, among them collection chutes for recyclable materials, photovoltaic panels incorporated into parts of its skin, and curtain-wall construction with exceptional shading and insulating properties.

These are all important innovations. In terms of the building’s true ecological impact, though, they are distinctly secondary. (The power generated by the photovoltaic panels supplies less than one per cent of the building’s requirements.) The two greenest features of 4 Times Square are ones that most people never even mention: it is big, and it is situated in Manhattan.

Environmentalists have tended to treat big buildings as intrinsically wasteful, because large amounts of energy are expended in their construction, and because the buildings place intensely localized stresses on sewers, power lines, and water systems. But density can create the same kinds of ecological benefits in individual structures that it does in entire communities. Tall buildings have much less exposed exterior surface per square foot of interior space than smaller buildings do, and that means they present relatively less of themselves to the elements, and their small roofs absorb less heat from the sun during cooling season and radiate less heat from inside during heating season.

(The beneficial effects are greater still in Manhattan, where one building often directly abuts another.) A study by Michael Phillips and Robert Gnaizda, published in CoEvolution Quarterly in 1980, found that an ordinary apartment in a typical building near downtown San Francisco used just a fifth as much heating fuel as a new tract house in Davis, a little more than seventy miles away. Occupants of tall buildings also do a significant part of their daily coming and going in elevators, which, because they are counterweighted and thus require less motor horsepower, are among the most energy efficient passenger vehicles in the world.

Bruce Fowle, a founder of Fox & Fowle, told me, “The Condé Nast Building contains 1.6 million square feet of floor space, and it sits on one acre of land. If you divided it into 48 one-story suburban office buildings, each averaging 33,000 square feet, and spread those one-story buildings around the countryside, and then added parking and some green space around each one, you’d end up consuming at least a 150 acres of land. And then you’d have to provide infrastructure, the highways and everything else.” Like many other buildings in Manhattan, 4 Times Square doesn’t even have a parking lot, because the vast majority of the six thousand people who work inside it don’t need one. In most other parts of the country, big parking lots are not only necessary but are required by law. If my town’s zoning regulations applied in Manhattan, 4 Times Square would have needed sixteen thousand parking spaces, one for every hundred square feet of office floor space. The Rocky Mountain Institute’s showcase headquarters has double-paned krypton-filled windows, which admit 75 per cent as much light as ordinary windows while allowing just 10 per cent as much heat to escape in cold weather. That’s a wonderful feature, and one of many in the building which people ought to copy. In other ways, though, the R.M.I. building sets a very poor environmental example. It was built in a fragile location, on virgin land more than seven thousand feet above sea level. With just four thousand square feet of interior space, it can hold only six of R.M.I.’s 18 full-time employees; the rest of them work in a larger building a mile away. Because the two buildings are in a thinly populated area, they force most employees to drive many miles-including trips between the two buildings-and they necessitate extra fuel consumption by delivery trucks, snowplows, and other vehicles. If R.M.I.’s employees worked on a single floor of a big building in Manhattan (or in downtown Denver) and lived in apartments nearby, many of them would be able to give up their cars, and the thousands of visitors who drive to Snowmass each year to learn about environmentally responsible construction could travel by public transit instead.

Picking on R.M.I.-which is one of the world’s most farsighted environmental organizations-may seem unfair, but R.M.I., along with many other farsighted environmental organizations, shares responsibility for perpetuating the powerful anti-city bias of American environmentalism. That bias is evident in the technical term that is widely used for sprawl: “urbanization.” Thinking of freeways and strip malls as “urban” phenomena obscures the ecologically monumental difference between Phoenix and Manhattan, and fortifies the perception that population density is an environmental ill. It also prevents most people from recognizing that R.M.I.’s famous headquarters-which sits on an isolated parcel more than a hundred and eighty miles from the nearest significant public transit system-is sprawl.

When I told a friend recently that I thought New York City should be considered the greenest community in America, she looked puzzled, then asked, “Is it because they’ve started recycling again?” Her question reflected a central failure of the American environmental movement: that too many of us have been made to believe that the most important thing we can do to save the earth and ourselves is to remember each week to set our cans and bottles and newspapers on the curb. Recycling is popular because it enables people to relieve their gathering anxieties about the future without altering the way they live. But most current recycling has, at best, a neutral effect on the environment, and much of it is demonstrably harmful. As William McDonough and Michael Braungart point out in “Cradle to Cradle: Remaking the Way We Make Things,” most of the materials we place on our curbs are merely “downcycled”-converted to a lower use, providing a pause in their inevitable journey to a landfill or an incinerator-often with a release of toxins and a net loss of fuel, among other undesirable effects.

By far the worst damage we Americans do to the planet arises not from the newspapers we throw away but from the eight hundred and fifty million or so gallons of oil we consume every day. We all know this at some level, yet we live like alcoholics in denial. How else can we explain that our cars have grown bigger, heavier, and less fuel efficient at the same time that scientists have become more certain and more specific about the consequences of our addiction to gasoline?

On a shelf in my office is a small pile of recent books about the environment which I plan to reread obsessively if I’m found to have a terminal illness, because they’re so unsettling that they may make me less upset about being snatched from life in my prime. At the top of the pile is “Out of Gas: The End of the Age of Oil,” by David Goodstein, a professor at the California Institute of Technology, which was published earlier this year. “The world will soon start to run out of conventionally produced, cheap oil,” Goodstein begins. In succeeding pages, he lucidly explains that humans have consumed almost a trillion barrels of oil (that’s forty-two trillion gallons), or about half of the earth’s total supply; that a devastating global petroleum crisis will begin not when we have pumped the last barrel out of the ground but when we have reached the halfway point, because at that moment, for the first time in history, the line representing supply will fall through the line representing demand; that we will probably pass that point within the current decade, if we haven’t passed it already; that various well-established laws of economics are about to assert themselves, with disastrous repercussions for almost everything; and that “civilization as we know it will come to an end sometime in this century unless we can find a way to live without fossil fuels.”

Standing between us and any conceivable solution to our energy nightmare are our cars and the asphalt-latticed country we have built to oblige them. Those cars have defined our culture and our lives. A car is speed and sex and power and emancipation. It makes its driver a self-sufficient nation of one. It is everything a city is not.

Most of the car’s most tantalizing charms are illusory, though. By helping us to live at greater distances from one another, driving has undermined the very benefits that it was meant to bestow. Ignacio San Martín, an architecture professor and the head of the graduate urban-design program at the University of Arizona, told me, “If you go out to the streets of Phoenix and are able to see anybody walking-which you likely won’t-they are going to tell you that they love living in Phoenix because they have a beautiful house and three cars. In reality, though, once the conversation goes a little bit further, they are going to say that they spend most of their time at home watching TV, because there is absolutely nothing to do.” One of the main attractions of moving to the suburbs is acquiring ground of your own, yet you can travel for miles through suburbia and see no one doing anything in a yard other than working on the yard itself (often with the help of a riding lawnmower, one of the few four-wheeled passenger vehicles that get worse gas mileage than a Hummer). The modern suburban yard is perfectly, perversely self-justifying: its purpose is to be taken care of.

In 1801, in his first Inaugural address, Thomas Jefferson said that the American wilderness would provide growing room for democracy-sustaining agrarian patriots “to the thousandth and thousandth generation.” Jefferson didn’t foresee the interstate highway system, and his arithmetic was off, in any case, but he nevertheless anticipated (and, in many ways, embodied) the ethos of suburbia, of anti-urbanism, of sprawl. The standard object of the modern American dream, the single-family home surrounded by grass, is a mini-Monticello. It was the car that put it within our reach. But what a terrible price we have paid-and have yet to pay-for our liberation from the city.

 

Economic Merits of Road Diets and Traffic Calming

By Dom Nozzi, AICP

In a great many cases, “improved safety” is a reason cited as a rationale for adding travel lanes to a road (“widening” a road). Indeed, because “improved safety” is a “moral high ground” argument (i.e., the argument should be accepted for ethical reasons), the safety rationale is perhaps the most common reason given for why a road “must” be widened.

In effect, public policy makers, when confronted with the “public safety” justification, are forced into an uncomfortable position when a decision must be made to widen or not widen a road: Either agree to the widening, or take a position that seems to suggest an uncaring attitude toward public safety.

It comes as no surprise that a large number of decision-makers are persuaded solely on the basis of the public safety argument.

Because road widenings are enormously expensive, speed up car traffic, and can profoundly worsen quality of life as well as accelerate strip commercial development and urban sprawl, we must be certain that road widenings do, in fact, deliver on the promise of dramatically improved safety.

The Forgiving Road

The “Forgiving Road” is a road that “forgives” a motorist when a driving mistake is made. That is, being reckless, or driving at high-speeds, or driving inattentively is not followed by the “punishment” of consequences such as crashing into something on the side of the road. For several decades, we have designed forgiving roads. We have been pulling buildings, parked cars, pedestrians, bicyclists, trees and other “obstructions” away from the sides of roads so that even an unskilled motorist can travel at high speeds without crashing into something.

The forgiving road was thought to be a way to promote “safety”(the hidden agenda, for many, was to promote high-speed travel by large volumes of car traffic).

Of course-human nature being what it is-such a design encourages reckless, high-speed, inattentive driving because human psychology compels us to tend to drive at the highest speed that still feels safe. After all, we are always “running late.” We are always in a hurry. And we are so busy.

The forgiving roadway lulls us into a false sense of security. Vigilance and concentration wane on the forgiving road. Is it any wonder that today, we increasingly see motorists driving at high speeds with one hand, while putting on make-up, drinking coffee, or chatting on the cell phone with the other?

Since we tend to be busy and in a hurry, forgiving streets deliver lots of motorists who drive as fast as they can and “multi-task” while driving. Why? To save time.

The predictable result: An increase in crashes due to speeding, inattentiveness, and recklessness.

Ironically, motorist safety declines and driving skills atrophy, because the forgiving street conditions motorists to be less careful drivers, and lowers the need to maintain or improve driving skills. Increasingly, American motorists drive dangerously, and more ineptly.

Three Lanes vs Four Lanes

Some safety analysts point out that 3-lane roads are noticeably safer than 4-lane roads, in part because, when comparing 3 lanes to 4, average vehicle speeds are reduced, there is less variability in vehicle speeds, and there is less speeding. In addition, there is a significant reduction in what engineers call “conflict” points, and an increase in “sight distance” for turning and crossing traffic on a 3-lane versus 4-lane road (Welch, undated).

This is particularly important for senior citizens who are motorists, because fewer conflict points and increased sight distances means fewer decisions and judgements have to be made to enter or cross a 3-lane road.

Similarly, a 3-lane road reduces the street-crossing distance for pedestrians. Compared to a 4-lane road, a 3-lane can create “refuge” areas where a pedestrian can safely wait until there is a safe gap in traffic before crossing the other half of the street. A refuge is also created for motorists with 3 lanes.

A review of the research on this question raises significant questions as to whether wider roads are safer roads.

Fewer Travel Lanes

A study published in 2002 (Huang, Stewart, Zegeer, 2002) reported that in Oakland CA, a street carrying 24,000 trips per day was converted from four lanes to three. The number of annual crashes went from 81 before to 68 after. On another street in Oakland was narrowed, crashes went down 52 percent. In Minnesota, a road diet resulted in a 33-percent reduction in injury crashes. In Billings MT, a road diet resulted in 62 percent fewer crashes after travel lanes were removed. In Lewistown PA, removal of travel lanes saw the number of crashes drop to almost zero. Finally, these researchers found that in Seattle WA, a number of road diets were analyzed, and a 34-percent reduction in total crashes and a 7-percent drop in injury crashes was noted.

The Surface Transportation Policy Project (1999) released a study in 1999 that found a strong link between aggressive driving deaths and increased road capacity. Those living in states with the largest number of lane miles per capita were 65 percent more likely to die in an aggressive driving crash than in states with less lane miles per capita. Similarly, those metro areas that added the most lane miles over a five-year period had higher levels of aggressive driving deaths. See their 2003 report for additional information about how big roads are less safe.

The Iowa Department of Transportation (2001) has found that converting a four-lane undivided road to three lanes can improve safety while retaining an acceptable level of service. Their review of research found that when such conversions occurred, there was a reduction in average speeds, a significant reduction in speeding, and a substantial reduction in the total number of crashes.

According to Engwicht (1989), straighter, wider roads encourage greater speed. Accidents that do happen are therefore more severe, resulting in more injuries or a greater likelihood of death.

There is a large body of research which suggests that increasing the safety of a car or road simply encourages the driver to take greater risks. Drivers are willing to take a certain amount of risk in exchange for the benefit of faster traveling time. This risk is added to the safety limits of the car or road. The new safety features lull the driver into a new sense of security. Vigilance, concentration and attentiveness wane.

Welch (Welch, undated) conducted an analysis of converting a two-lane road to a four-lane road in Ft. Madison IA. This conversion resulted in a 4 percent increase in traffic volume, a 4 percent increase in corridor travel delay, a 2.5 mph increase in mid-block 85th percentile speed, a 14 percent increase in accidents and an 88 percent increase in injuries. The report also found that traffic traveling more than 5 mph over speed limit increased from 0.5% to 4.2%.

Welch reports that in Billings MT, when a four-lane was converted to a three-lane road, the number of reported accidents decreased from 37 in the 20 months before to 14 in the 20 months after conversion. No increase in traffic delay was found.

Despite initial apprehension from the local community and its engineers, Welch indicates that a conversion from four lanes to three in Storm Lake IA (US 71) resulted in an observed improvement in safety (“an immediate large reduction in accidents”). The Iowa DOT Office of Transportation Safety has begun actively promoting conversion of four-lane roads to three-lane when a concern about safety is expressed. In Helena MT, an urban primary highway (US 12) was converted from four lanes to three. (City staff and other state staff engineers now support the conversion after observing an improvement in traffic operations and a reduction in accidents.) In a study conducted for the Minnesota DOT, it was found that the highest urban corridor accident rates are found on four-lane undivided roads. In fact, the collision rate was 35 percent higher than on urban three-lane roads. Howard Preston, who conducted the study, stated that he would convert most four-lane roads with less than 20,000 car trips per day to three-lane roads “in a heartbeat.”

In Duluth MN, a conversion from four lanes to three (21st Ave East) was initially opposed by many. After conversion, the Duluth News-Tribune editorial had this to say: “When Duluth officials announced they would convert busy 21st Avenue East…from four lanes to two, with a turn lane in the middle, some armchair analysts predicted it wouldn’t work. The News-Tribune Opinion page was among them. Well, it works. About everyone agrees-from city traffic officials to neighbors-that the change has eased congestion and reduced drivers’ speed making it safer for pedestrians…”

Frequently, according to Welch, emergency vehicles find it difficult to travel down four-lane roads. Emergency vehicles typically need to wait for traffic to move over to the curb lane to get out of the way. But a center two-way left-turn lane usually has less vehicle conflicts, and often produces less delay for emergency vehicles traveling down it.

Hoyle (1995) points out that widened roads are alleged to be safer roads based on data provided by those in favor of many road widenings. However, data showing a decrease in crashes per vehicle mile don’t take into account the fact that widened roads encourage extra car trips that would not have happened had the road not been widened. Widened roads also encourage longer trip lengths. When such factors are taken into account, crash rates per trip or per hour spent on the road remain nearly the same.

Michael Ronkin (2001) suggests that the most effective way to reduce vehicle speed is by reducing the number of road lanes. “With two lanes in each direction, regardless of width, a driver who wants to move faster than the car in front can get into the adjacent lane and pass. With one lane in each direction, the slowest car sets the pace for all cars behind it.” While driving in Boston recently, he found that “lanes are narrow, very narrow, but on multi-lane one-way streets, cars zipped along at incredibly high speeds for urban streets, around 40 MPH…”

Ronkin notes a great deal of misunderstanding among pedestrian advocates about the speeds. “Pedestrians are more threatened by the occasional car going much faster than reasonable, than by cars travelling at an average speed.” On multi-lane roads, “the crossing pedestrian has several threats and challenges: the possibility of a car going faster than the rest of traffic could be invisible as it is masked by another car, its speed may not be apparent to the pedestrian. That makes it very difficult to judge adequate gaps. With one lane in each direction, a gap is a gap.”

One of the most frequent types of fatal crashes “is the multiple threat-a driver stops to let pedestrian cross on a multi-lane road, and the pedestrian is struck (and usually killed) by a driver passing in the adjacent lane.” Ronkin points out that this type of crash is not possible if there is no adjacent lane.

For Ronkin, another important contributor to crashes, besides speed, is the “complexity” involved in crossing a street. After analyzing a great many fatal crashes, he concludes that many of those crashes presented both the pedestrian and the driver with a relatively complex situation. According to Ronkin, “there just wasn’t enough time for both parties to react to an unforeseen event.” He concludes by pointing out the importance, in designing a road crossing, of creating an environment that that minimizes the number of decisions that must be made simultaneously..

In sum, Ronkin indicates that there have been “demonstrated reductions in crashes” when a road had lanes removed-convincingly so.

Narrow Lanes

Joseph R. Molinaro (1991) reports that wider travel lanes are more dangerous because they encourage higher-speed driving. Larger neighborhood collector streets work well with only 26 feet of width, and smaller neighborhood streets are safe at 20-24 feet. He also points out that residential streets should use tighter turns in order to force slower motorist speeds. With a smaller turn radius, motorists are more likely to come to a full stop than a more dangerous rolling stop.

The ITE Transportation Planning Council Committee (ITE, undated) cites the American Association of State Highway Officials, which found that “‘[t]he number of accidents increases with an increase in the number of decisions required by the driver.’ A corollary to this truism is that the actual and potential effects of each driver-decision become more significant as the speed of the particular motor vehicle increases.”

It is quite common for engineers to design a road for the rare large truck. Such design requires large turning radii and wide travel lanes. These relatively large dimensions far exceed those of passenger cars most common on residential streets. The overscaled design of these roads encourage faster passenger car speeds by the most frequent motor vehicles on these roads.

“Clearly, reducing the width of a street,” according to ITE, “has the effect of reducing vehicular speeds.”

The Conservation Law Foundation (1995) finds that vehicle speeds increase when roads are widened because there is an extra “safety cushion” provided by the increased lateral distances and increased sight distances. Psychologically, the wider road tells the motorist that it is safer to speed up, and since motorists tend to drive at the fastest speed they feel safe at, faster speeds are seen on wider roads with a higher perceived “safety cushion.” In addition, the field of vision of the motorist shrinks as speed increases, which reduces the ability of the motorist to see things (such as cars or pedestrians) that are ahead.

The Foundation also points out that designing for faster driving speeds, while possibly reducing the frequency of crashes, also increase the severity of car crashes.

Swift, Painter, and Goldstein (1998) conducted a study that analyzed the safest street widths with regard to accident frequency. Their study found that “as street width widens, accidents per mile per year increases exponentially, and that the safest residential street width is 24 feet (curb face).”

Indeed, crash rates were 18 times higher on 48-foot wide streets than on 24-foot wide streets.

The authors concluded, in part, by calling for a re-evaluation of public safety. That local governments recognize that the chance of injury or death due to, say, a neighborhood fire, is quite small compared to the much higher probability of injury or death in a neighborhood due to speeding traffic. That the reduced number of injuries or deaths resulting from wide streets and allegedly faster fire truck response time is tiny in comparison to the comparatively large number of injuries or deaths that occur due to speeding cars-a problem that increases in frequency due to widened streets. The local government should “ask if it is better to reduce dozens of potential vehicle accidents, injuries and deaths [through the creation of more modest streets], or provide wide streets for no apparent benefit to fire-related injuries or deaths.”

Even if more modest streets increased fire injury risks slightly (a problem not found by the study), modest streets would still be safer than wide streets because the risk of car injuries is so much higher than fire injuries.

In other words, by focusing public safety on life safety, rather than fire safety, a much larger number of community injuries and deaths can be managed and perhaps reduced.

A large number of firefighters are starting to understand that over-sized streets have resulted in streets that are not safe for families, while providing few, if any, benefits regarding fire safety and emergency response times, according to Siegman (2002).

Siegman relates a story from Dan Burden, a colleague who works in the field of safe street design:

While in Honolulu last week doing two school traffic calming charrettes our team had two tragic nights. In both cases a squad of firemen were with us for the evening, learning about and giving good input into traffic calming their neighborhoods. They had their truck with them in case they received a call. When asked by a member of the audience what they thought of the traffic calming plan the Captain said that they rarely, if ever, can expect a fire in the area….and that their concern is to lessen the speeds on area roads so that they are protecting rather than rescuing lives. They had good reason to say this … during the evening the firemen were called out to respond to a pedestrian tragedy several blocks from our meeting room, and in our project site.

The next school traffic calming meeting we again had four firemen, and their apparatus. We had just settled them down to a design table to design traffic calming solutions when they leaped up to attend a call. They, too, came back before the meeting was over. They had provided first assistance for a head-on crash of two motorists.

The meeting ended at 9:00. At 9:05 a bicyclist was hit (and presumably attended by these firemen). The cyclist was a star athlete on the University of Honolulu campus. She was killed one block from our school, in one of our crosswalks.

“Many firefighters,” according to Siegman, “realize that traffic crashes are a far greater hazard in our communities than fires, because they so often have to pick up the pieces.”

Siegman reminds us that “for every one person killed in a fire, more than eleven die in traffic crashes. And that for every one person injured by fire, 148 are injured in traffic crashes.”

A great many firefighters also tell us that fire truck response time does not depend simply on the width of a street.

For example, Siegman tells us that fire departments know that response time is a product of the speed of travel and the distance from the firehouse.

When streets are walkable and connected as they were in traditionally designed neighborhoods, they “usually allow far more direct routing than disconnected cul-de-sac designs.” Even when narrow (or “skinny”), the connected streets, Siegman points out, “can often deliver equal or better response times.” Connected streets also reduce the probability of traffic congestion, and congestion slows response times. “That understanding,” notes Siegman, “is apparently not yet reflected in fire codes, which discuss street width, but…have no specifications whatsoever on directness of routing, or distance from home to the arterial, or to the fire station.”

Siegman points out that a number of other fire departments are “no longer ordering U.S.-made fire engines, choosing instead the more maneuverable European models, which work well with smaller, safer, pedestrian-friendly street designs.”

According to Siegman, “we aren’t yet at the stage where all firefighters have excellent training in street design and traffic safety.” He wonders “how many communities still design their streets and intersections to accommodate the largest fire truck in the fleet, without having weighed pedestrian safety effects as part of the truck purchase.”

In conclusion, Siegman presents us with the following eye-opening statistics for fire and traffic fatalities and injuries in 1999 in the United States. In that year, “3,570 civilian (i.e. non-firefighter)” fire deaths occurred, and 21,875 civilians were injured. In addition, 112 fire fighters died while on duty-11 of them in traffic crashes. He also reports that “41,611 people were killed and 3,236,000 people were injured in the estimated 6,279,000 police-reported motor vehicle traffic crashes. 4,188,000 crashes involved property damage only.”

As reported by Finch (1994) and Preston (1995), every one mph reduction in traffic speed, in general, reduces vehicle collisions by five percent, and reduces fatalities to an even greater extent.

Narrowing travel lanes made things safer unless the narrowing was done to accommodate more travel lanes, according to a report from the Transportation Research Board (1994).

References Cited

Conservation Law Foundation. Take Back Your Streets. Boston MA. May 1995.

Engwicht, D. (ed.) Traffic Calming: The Solution to Urban Traffic and a New Vision for Neighborhood Livability. 1989.

Finch, D.J., Kompfner, P., Lockwood, C.R., Maycock, G. Speed, Speed Limits and Accidents. Transport Research Laboratory (Crowthorne, UK), Report 58, 1994.

Hoyle, C. Traffic Calming. American Planning Association. Planning Advisory Service Report Number 456. 1995.

Huang, H.F., Stewart, J.R. and Zegeer, C.V. Evaluation of Lane Reduction “Road Diet” Measures on Crashes and Injuries. Transportation Research Record 1784: 80-90. 2002.

Iowa Department of Transportation. Guidelines for the Conversion of Urban 4-lane Undivided Roadways to 3-lane Two-Way Left-turn Lane Facilities. April 2001.

ITE Transportation Planning Council Committee, Traditional Neighborhood Development: Street Design Guidelines. 5P-8. Undated.

Molinaro, J.R. Rethinking Residential Streets. Planning Commissioners Journal. Vol. 1:1. November/December 1991.

Preston, B. “Cost Effective Ways to Make Walking Safer for Children and Adolescents,” Injury Prevention, 1995, pp. 187-190.

Ronkin, M. Pedestrian & Bicycle Program Manager, Oregon Department of Transportation. March 27, 2001.

Siegman, P. Siegman & Associates, Town & Transportation Planning, 260 Palo Alto Avenue, Palo Alto, CA 94301. August 4, 2002 email submitted to a Dan Burden/Walkable Communities internet discussion group.

Surface Transportation Policy Project. Aggressive Driving. Washington DC. April 1999.

Swift, P., Painter, D. and Goldstein M. Residential Street Typology and Injury Accident Frequency. Copyright Peter Swift, Swift and Associates. 1998.

Transportation Research Board. Low-volume rural roads (Roadway Widths for Low-Traffic-Volume Roads). Transportation Research Board. NR362, 1994.

Welch, T.M. The Conversion of Four-Lane Undivided Urban Roadways to Three-Lane Facilities. Transportation Research Board. TRB Circular E-C019: Urban Street Symposium. Undated.

 

Bigger Roads are Less Safe (despite what your traffic engineer says)

Dom Nozzi, AICP

In a great many cases, “improved safety” is a reason cited as a rationale for adding travel lanes to a road (“widening” a road). Indeed, because “improved safety” is a “moral high ground” argument (i.e., the argument should be accepted for ethical reasons), the safety rationale is perhaps the most common reason given for why a road “must” be widened.

In effect, public policy makers, when confronted with the “public safety” justification, are forced into an uncomfortable position when a decision must be made to widen or not widen a road: Either agree to the widening, or take a position that seems to suggest an uncaring attitude toward public safety.

It comes as no surprise that a large number of decision-makers are persuaded solely on the basis of the public safety argument.

Because road widenings are enormously expensive, speed up car traffic, and can profoundly worsen quality of life as well as accelerate strip commercial development and urban sprawl, we must be certain that road widenings do, in fact, deliver on the promise of dramatically improved safety.

The Forgiving Road

The “Forgiving Road” is a road that “forgives” a motorist when a driving mistake is made. That is, being reckless, or driving at high-speeds, or driving inattentively is not followed by the “punishment” of consequences such as crashing into something on the side of the road. For several decades, we have designed forgiving roads. We have been pulling buildings, parked cars, pedestrians, bicyclists, trees and other “obstructions” away from the sides of roads so that even an unskilled motorist can travel at high speeds without crashing into something.

The forgiving road was thought to be a way to promote “safety”(the hidden agenda, for many, was to promote high-speed travel by large volumes of car traffic).

Of course-human nature being what it is-such a design encourages reckless, high-speed, inattentive driving because human psychology compels us to tend to drive at the highest speed that still feels safe. After all, we are always “running late.” We are always in a hurry. And we are so busy.

The forgiving roadway lulls us into a false sense of security. Vigilance and concentration wane on the forgiving road. Is it any wonder that today, we increasingly see motorists driving at high speeds with one hand, while putting on make-up, drinking coffee, or chatting on the cell phone with the other?

Since we tend to be busy and in a hurry, forgiving streets deliver lots of motorists who drive as fast as they can and “multi-task” while driving. Why? To save time.

The predictable result: An increase in crashes due to speeding, inattentiveness, and recklessness.

Ironically, motorist safety declines and driving skills atrophy, because the forgiving street conditions motorists to be less careful drivers, and lowers the need to maintain or improve driving skills. Increasingly, American motorists drive dangerously, and more ineptly.

Three Lanes vs Four Lanes

Some safety analysts point out that 3-lane roads are noticeably safer than 4-lane roads, in part because, when comparing 3 lanes to 4, average vehicle speeds are reduced, there is less variability in vehicle speeds, and there is less speeding. In addition, there is a significant reduction in what engineers call “conflict” points, and an increase in “sight distance” for turning and crossing traffic on a 3-lane versus 4-lane road (Welch, undated).

This is particularly important for senior citizens who are motorists, because fewer conflict points and increased sight distances means fewer decisions and judgements have to be made to enter or cross a 3-lane road.

Similarly, a 3-lane road reduces the street-crossing distance for pedestrians. Compared to a 4-lane road, a 3-lane can create “refuge” areas where a pedestrian can safely wait until there is a safe gap in traffic before crossing the other half of the street. A refuge is also created for motorists with 3 lanes.

A review of the research on this question raises significant questions as to whether wider roads are safer roads.

Fewer Travel Lanes

A study published in 2002 (Huang, Stewart, Zegeer, 2002) reported that in Oakland CA, a street carrying 24,000 trips per day was converted from four lanes to three. The number of annual crashes went from 81 before to 68 after. On another street in Oakland was narrowed, crashes went down 52 percent. In Minnesota, a road diet resulted in a 33-percent reduction in injury crashes. In Billings MT, a road diet resulted in 62 percent fewer crashes after travel lanes were removed. In Lewistown PA, removal of travel lanes saw the number of crashes drop to almost zero. Finally, these researchers found that in Seattle WA, a number of road diets were analyzed, and a 34-percent reduction in total crashes and a 7-percent drop in injury crashes was noted.

The Surface Transportation Policy Project (1999) released a study in 1999 that found a strong link between aggressive driving deaths and increased road capacity. Those living in states with the largest number of lane miles per capita were 65 percent more likely to die in an aggressive driving crash than in states with less lane miles per capita. Similarly, those metro areas that added the most lane miles over a five-year period had higher levels of aggressive driving deaths. See their 2003 report for additional information about how big roads are less safe.

The Iowa Department of Transportation (2001) has found that converting a four-lane undivided road to three lanes can improve safety while retaining an acceptable level of service. Their review of research found that when such conversions occurred, there was a reduction in average speeds, a significant reduction in speeding, and a substantial reduction in the total number of crashes.

According to Engwicht (1989), straighter, wider roads encourage greater speed. Accidents that do happen are therefore more severe, resulting in more injuries or a greater likelihood of death.

There is a large body of research which suggests that increasing the safety of a car or road simply encourages the driver to take greater risks. Drivers are willing to take a certain amount of risk in exchange for the benefit of faster traveling time. This risk is added to the safety limits of the car or road. The new safety features lull the driver into a new sense of security. Vigilance, concentration and attentiveness wane.

Welch (Welch, undated) conducted an analysis of converting a two-lane road to a four-lane road in Ft. Madison IA. This conversion resulted in a 4 percent increase in traffic volume, a 4 percent increase in corridor travel delay, a 2.5 mph increase in mid-block 85th percentile speed, a 14 percent increase in accidents and an 88 percent increase in injuries. The report also found that traffic traveling more than 5 mph over speed limit increased from 0.5% to 4.2%.

Welch reports that in Billings MT, when a four-lane was converted to a three-lane road, the number of reported accidents decreased from 37 in the 20 months before to 14 in the 20 months after conversion. No increase in traffic delay was found.

Despite initial apprehension from the local community and its engineers, Welch indicates that a conversion from four lanes to three in Storm Lake IA (US 71) resulted in an observed improvement in safety (“an immediate large reduction in accidents”). The Iowa DOT Office of Transportation Safety has begun actively promoting conversion of four-lane roads to three-lane when a concern about safety is expressed. In Helena MT, an urban primary highway (US 12) was converted from four lanes to three. (City staff and other state staff engineers now support the conversion after observing an improvement in traffic operations and a reduction in accidents.) In a study conducted for the Minnesota DOT, it was found that the highest urban corridor accident rates are found on four-lane undivided roads. In fact, the collision rate was 35 percent higher than on urban three-lane roads. Howard Preston, who conducted the study, stated that he would convert most four-lane roads with less than 20,000 car trips per day to three-lane roads “in a heartbeat.”

In Duluth MN, a conversion from four lanes to three (21st Ave East) was initially opposed by many. After conversion, the Duluth News-Tribune editorial had this to say: “When Duluth officials announced they would convert busy 21st Avenue East…from four lanes to two, with a turn lane in the middle, some armchair analysts predicted it wouldn’t work. The News-Tribune Opinion page was among them. Well, it works. About everyone agrees-from city traffic officials to neighbors-that the change has eased congestion and reduced drivers’ speed making it safer for pedestrians…”

Frequently, according to Welch, emergency vehicles find it difficult to travel down four-lane roads. Emergency vehicles typically need to wait for traffic to move over to the curb lane to get out of the way. But a center two-way left-turn lane usually has less vehicle conflicts, and often produces less delay for emergency vehicles traveling down it.

Hoyle (1995) points out that widened roads are alleged to be safer roads based on data provided by those in favor of many road widenings. However, data showing a decrease in crashes per vehicle mile don’t take into account the fact that widened roads encourage extra car trips that would not have happened had the road not been widened. Widened roads also encourage longer trip lengths. When such factors are taken into account, crash rates per trip or per hour spent on the road remain nearly the same.

Michael Ronkin (2001) suggests that the most effective way to reduce vehicle speed is by reducing the number of road lanes. “With two lanes in each direction, regardless of width, a driver who wants to move faster than the car in front can get into the adjacent lane and pass. With one lane in each direction, the slowest car sets the pace for all cars behind it.” While driving in Boston recently, he found that “lanes are narrow, very narrow, but on multi-lane one-way streets, cars zipped along at incredibly high speeds for urban streets, around 40 MPH…”

Ronkin notes a great deal of misunderstanding among pedestrian advocates about the speeds. “Pedestrians are more threatened by the occasional car going much faster than reasonable, than by cars travelling at an average speed.” On multi-lane roads, “the crossing pedestrian has several threats and challenges: the possibility of a car going faster than the rest of traffic could be invisible as it is masked by another car, its speed may not be apparent to the pedestrian. That makes it very difficult to judge adequate gaps. With one lane in each direction, a gap is a gap.”

One of the most frequent types of fatal crashes “is the multiple threat-a driver stops to let pedestrian cross on a multi-lane road, and the pedestrian is struck (and usually killed) by a driver passing in the adjacent lane.” Ronkin points out that this type of crash is not possible if there is no adjacent lane.

For Ronkin, another important contributor to crashes, besides speed, is the “complexity” involved in crossing a street. After analyzing a great many fatal crashes, he concludes that many of those crashes presented both the pedestrian and the driver with a relatively complex situation. According to Ronkin, “there just wasn’t enough time for both parties to react to an unforeseen event.” He concludes by pointing out the importance, in designing a road crossing, of creating an environment that that minimizes the number of decisions that must be made simultaneously..

In sum, Ronkin indicates that there have been “demonstrated reductions in crashes” when a road had lanes removed-convincingly so.

Narrow Lanes

Joseph R. Molinaro (1991) reports that wider travel lanes are more dangerous because they encourage higher-speed driving. Larger neighborhood collector streets work well with only 26 feet of width, and smaller neighborhood streets are safe at 20-24 feet. He also points out that residential streets should use tighter turns in order to force slower motorist speeds. With a smaller turn radius, motorists are more likely to come to a full stop than a more dangerous rolling stop.

The ITE Transportation Planning Council Committee (ITE, undated) cites the American Association of State Highway Officials, which found that “‘[t]he number of accidents increases with an increase in the number of decisions required by the driver.’ A corollary to this truism is that the actual and potential effects of each driver-decision become more significant as the speed of the particular motor vehicle increases.”

It is quite common for engineers to design a road for the rare large truck. Such design requires large turning radii and wide travel lanes. These relatively large dimensions far exceed those of passenger cars most common on residential streets. The overscaled design of these roads encourage faster passenger car speeds by the most frequent motor vehicles on these roads.

“Clearly, reducing the width of a street,” according to ITE, “has the effect of reducing vehicular speeds.”

The Conservation Law Foundation (1995) finds that vehicle speeds increase when roads are widened because there is an extra “safety cushion” provided by the increased lateral distances and increased sight distances. Psychologically, the wider road tells the motorist that it is safer to speed up, and since motorists tend to drive at the fastest speed they feel safe at, faster speeds are seen on wider roads with a higher perceived “safety cushion.” In addition, the field of vision of the motorist shrinks as speed increases, which reduces the ability of the motorist to see things (such as cars or pedestrians) that are ahead.

The Foundation also points out that designing for faster driving speeds, while possibly reducing the frequency of crashes, also increase the severity of car crashes.

Swift, Painter, and Goldstein (1998) conducted a study that analyzed the safest street widths with regard to accident frequency. Their study found that “as street width widens, accidents per mile per year increases exponentially, and that the safest residential street width is 24 feet (curb face).”

Indeed, crash rates were 18 times higher on 48-foot wide streets than on 24-foot wide streets.

The authors concluded, in part, by calling for a re-evaluation of public safety. That local governments recognize that the chance of injury or death due to, say, a neighborhood fire, is quite small compared to the much higher probability of injury or death in a neighborhood due to speeding traffic. That the reduced number of injuries or deaths resulting from wide streets and allegedly faster fire truck response time is tiny in comparison to the comparatively large number of injuries or deaths that occur due to speeding cars-a problem that increases in frequency due to widened streets. The local government should “ask if it is better to reduce dozens of potential vehicle accidents, injuries and deaths [through the creation of more modest streets], or provide wide streets for no apparent benefit to fire-related injuries or deaths.”

Even if more modest streets increased fire injury risks slightly (a problem not found by the study), modest streets would still be safer than wide streets because the risk of car injuries is so much higher than fire injuries.

In other words, by focusing public safety on life safety, rather than fire safety, a much larger number of community injuries and deaths can be managed and perhaps reduced.

A large number of firefighters are starting to understand that over-sized streets have resulted in streets that are not safe for families, while providing few, if any, benefits regarding fire safety and emergency response times, according to Siegman (2002).

Siegman relates a story from Dan Burden, a colleague who works in the field of safe street design:

While in Honolulu last week doing two school traffic calming charrettes our team had two tragic nights. In both cases a squad of firemen were with us for the evening, learning about and giving good input into traffic calming their neighborhoods. They had their truck with them in case they received a call. When asked by a member of the audience what they thought of the traffic calming plan the Captain said that they rarely, if ever, can expect a fire in the area….and that their concern is to lessen the speeds on area roads so that they are protecting rather than rescuing lives. They had good reason to say this … during the evening the firemen were called out to respond to a pedestrian tragedy several blocks from our meeting room, and in our project site.

The next school traffic calming meeting we again had four firemen, and their apparatus. We had just settled them down to a design table to design traffic calming solutions when they leaped up to attend a call. They, too, came back before the meeting was over. They had provided first assistance for a head-on crash of two motorists.

The meeting ended at 9:00. At 9:05 a bicyclist was hit (and presumably attended by these firemen). The cyclist was a star athlete on the University of Honolulu campus. She was killed one block from our school, in one of our crosswalks.

“Many firefighters,” according to Siegman, “realize that traffic crashes are a far greater hazard in our communities than fires, because they so often have to pick up the pieces.”

Siegman reminds us that “for every one person killed in a fire, more than eleven die in traffic crashes. And that for every one person injured by fire, 148 are injured in traffic crashes.”

A great many firefighters also tell us that fire truck response time does not depend simply on the width of a street.

For example, Siegman tells us that fire departments know that response time is a product of the speed of travel and the distance from the firehouse.

When streets are walkable and connected as they were in traditionally designed neighborhoods, they “usually allow far more direct routing than disconnected cul-de-sac designs.” Even when narrow (or “skinny”), the connected streets, Siegman points out, “can often deliver equal or better response times.” Connected streets also reduce the probability of traffic congestion, and congestion slows response times. “That understanding,” notes Siegman, “is apparently not yet reflected in fire codes, which discuss street width, but…have no specifications whatsoever on directness of routing, or distance from home to the arterial, or to the fire station.”

Siegman points out that a number of other fire departments are “no longer ordering U.S.-made fire engines, choosing instead the more maneuverable European models, which work well with smaller, safer, pedestrian-friendly street designs.”

According to Siegman, “we aren’t yet at the stage where all firefighters have excellent training in street design and traffic safety.” He wonders “how many communities still design their streets and intersections to accommodate the largest fire truck in the fleet, without having weighed pedestrian safety effects as part of the truck purchase.”

In conclusion, Siegman presents us with the following eye-opening statistics for fire and traffic fatalities and injuries in 1999 in the United States. In that year, “3,570 civilian (i.e. non-firefighter)” fire deaths occurred, and 21,875 civilians were injured. In addition, 112 fire fighters died while on duty-11 of them in traffic crashes. He also reports that “41,611 people were killed and 3,236,000 people were injured in the estimated 6,279,000 police-reported motor vehicle traffic crashes. 4,188,000 crashes involved property damage only.”

As reported by Finch (1994) and Preston (1995), every one mph reduction in traffic speed, in general, reduces vehicle collisions by five percent, and reduces fatalities to an even greater extent.

Narrowing travel lanes made things safer unless the narrowing was done to accommodate more travel lanes, according to a report from the Transportation Research Board (1994).

References Cited

Conservation Law Foundation. Take Back Your Streets. Boston MA. May 1995.

Engwicht, D. (ed.) Traffic Calming: The Solution to Urban Traffic and a New Vision for Neighborhood Livability. 1989.

Finch, D.J., Kompfner, P., Lockwood, C.R., Maycock, G. Speed, Speed Limits and Accidents. Transport Research Laboratory (Crowthorne, UK), Report 58, 1994.

Hoyle, C. Traffic Calming. American Planning Association. Planning Advisory Service Report Number 456. 1995.

Huang, H.F., Stewart, J.R. and Zegeer, C.V. Evaluation of Lane Reduction “Road Diet” Measures on Crashes and Injuries. Transportation Research Record 1784: 80-90. 2002.

Iowa Department of Transportation. Guidelines for the Conversion of Urban 4-lane Undivided Roadways to 3-lane Two-Way Left-turn Lane Facilities. April 2001.

ITE Transportation Planning Council Committee, Traditional Neighborhood Development: Street Design Guidelines. 5P-8. Undated.

Molinaro, J.R. Rethinking Residential Streets. Planning Commissioners Journal. Vol. 1:1. November/December 1991.

Preston, B. “Cost Effective Ways to Make Walking Safer for Children and Adolescents,” Injury Prevention, 1995, pp. 187-190.

Ronkin, M. Pedestrian & Bicycle Program Manager, Oregon Department of Transportation. March 27, 2001.

Siegman, P. Siegman & Associates, Town & Transportation Planning, 260 Palo Alto Avenue, Palo Alto, CA 94301. August 4, 2002 email submitted to a Dan Burden/Walkable Communities internet discussion group.

Surface Transportation Policy Project. Aggressive Driving. Washington DC. April 1999.

Swift, P., Painter, D. and Goldstein M. Residential Street Typology and Injury Accident Frequency. Copyright Peter Swift, Swift and Associates. 1998.

Transportation Research Board. Low-volume rural roads (Roadway Widths for Low-Traffic-Volume Roads). Transportation Research Board. NR362, 1994.

Welch, T.M. The Conversion of Four-Lane Undivided Urban Roadways to Three-Lane Facilities. Transportation Research Board. TRB Circular E-C019: Urban Street Symposium. Undated.

 

Research Showing Road Widening Does Not Reduce Congestion

By Dom Nozzi, AICP

Below is a sample of research in the field that has found that widening (or new beltways) generates more traffic — traffic that would have not occurred had the road not been widened.

In other words, a self-fulfilling prophecy.

We spend huge sums of public tax revenue to worsen our congestion problems, promote suburban sprawl, increase auto dependence, and worsen our overall quality of life.

We are, indeed, our own worst enemy.

 

Note that this is a SAMPLE of research. A Google search would turn up quite a few additional studies.

 

Arnott, R., and Small, K. (1994). The economics of traffic congestion. American Scientist. Vol. 82. Sept/Oct. pp. 446-455.

Cohen, H. (1995). Review of empirical studies of induced traffic. Transportation Research Board. Special Report No. 345. National Academy Press. Appendix B. pp. 295-309.

Goddard, S.B. (1994). Getting there. The University of Chicago Press, Chicago.

Goodwin, P.B. (1994). Traffic reduction. Transport Policy. 1 (2): 83-84.

Goodwin, P. (1996). Empirical evidence on induced traffic. Transportation. 23 (1). pp. 35-54.

Hansen, M., and Huang, Y. (1997). Road supply and traffic in California urban areas. Transportation Research A. 31 (3), pp. 205-218. pp. 205-218.

Hansen, M. (1995). Do new highways generate traffic? Access. No. 7. Fall. pp. 16-22. pp. 16-22.

Hart, S. (1993). The elephant in the bedroom. New Paradigm Books, Pasadena.

Hills, P. (1996). What is induced traffic? Transportation. 23 (1). February. pp. 5-16.

Mogridge, M. (1997). The self-defeating nature of urban road capacity policy. Transport Policy. 4 (1). January. pp. 5-23.

National Highway Institute (1995). Estimating the impacts of urban transportation alternatives. NHI Course No. 15257. Federal Highway Administration, Washington, D.C. December.

Newman, P., and Kenworthy, J. (1989). Cities and automobile dependence: An international sourcebook. Gower, Aldershot, England.

Noland, R. (1999). Relationships between highway capacity and induced vehicle travel. Transportation Research Board, Annual Meeting. Paper 991069. January.

Noland, R. (2001). Relationships between highway capacity and induced vehicle travel. Transportation Research A, 35 (1): 47-72.

Pfleiderer, R., and Dieterich, M. (1995). New roads generate new traffic. World Transport Policy and Practice. 1 (1). pp. 29-31.

Standing Advisory Committee on Trunk Road Assessment (1994). Trunk roads and the generation of traffic. Department of Transport, United Kingdom. p. 47.

Surface Transportation Policy Project (1998). An analysis of the relationship between highway expansion and congestion in metropolitan areas: Lessons from the 15-year Texas Transportation Institute study. Washington, D.C.

Williams, H.C.W.L., and Yamashita, Y. (1992). Travel demand forecasts and the evaluation of highway schemes under congested conditions. Journal of Transport Economics and Policy, 26 (3): 261-282.

 

Note:

Generated traffic is sometimes confused with induced travel. Generated traffic is the increased traffic caused by road modifications which (temporarily) reduce motorist travel costs-such as road widening. Generated traffic increases traffic due to an increase in the number of trips on a route, and the trips diverted to the route from other times or other routes. Induced travel is the increase in trips and an increase in distance travel that is caused by the reduction of travel costs, excluding the diverted traffic. See Litman, T. (2001). Generated traffic: Implications for transport planning, ITE Journal 71 (4): 38-47. Washington, D.C. April.