Transportation and the Environment
General Information

I. Introduction

The U.S. economy has been driven to an extraordinary degree by the free access of its highways to all of its citizens, the elimination of barriers to inter-state commerce as prescribed by the U.S. Constitution, and the government funding of a high-quality road network from coast to coast, north to south. Other forms of transportation have also greatly benefited the U.S. economy. The importance of transportation is so great that the price of gasoline is often seen as a main economic indicator of future price rises and falls.

That same transportation system, whether it be truck and car, aviation, or ship, contributes a wide range of direct and indirect stressors to the environment. The detrimental role of transportation on the environment is difficult to exaggerate. Indeed, the role of U.S. transportation on global variability is also extraordinary. More than one-fifth of the planet’s carbon dioxide production is created by different forms of U.S. transportation. Cost-benefit analyses suggest that the price of gasoline and other transportation fuels by no means reflect the actual environmental damage those forms of transportation cause.

It was not until 1920 that the Census Bureau counted more Americans living in urban areas than in rural areas. With the advent of mass transit and the automobile in later decades, city dwellers began to move to low-density suburbs. In 1990, the Census Bureau found that nearly half of all Americans lived in the suburbs. Life in the suburbs necessitated daily transportation over large distances for purposes of both work and recreation.

Recreation has surpassed work trips in recent decades in contributing to the total miles traveled in the United States. Advocates of higher density say that it will improve urban livability. Because people will live more closely together, they will reduce auto usage and environmental impacts due to transportation. More people will walk or ride on mass transit, it is argued.

One solution proposed for combating urban sprawl is to encourage higher population densities through legislative tools and policies. Government planners are beginning to require new residential developments to house more people per given area. Existing low-density suburbs are supposed to be rebuilt to higher densities through infilling techniques. Those tools of policy-makers remain hotly contested and appear in many cases to infringe on the citizen’s individual property and other rights.

Smart growth instruments, represented by such legislative tools as Washington State’s Growth Management Act, have been largely controversial. Their results are still being evaluated and firm conclusions have still not been reached as to smart growth’s effectiveness. A wide range of proponents and critics continue to debate the subject.

Critics argue that hopes for reducing auto usage in most U.S. suburbs are unrealistic. Ninety percent of commuters drive to work until densities are above 5,000 per square mile. Even above that density, huge changes in density are needed to significantly change driving behavior. For example, quadrupling Seattle's density from 5,000 per square mile to New York's 20,000 might cut per capita driving in half. But with four times as many people, twice as much traffic would be on the roads.

It is further argued that that simply quadrupling density would lead Seattle to achieve New York's low driving rates. But the local economy plays an essential role in the formula. Unlike Seattle, New York enjoys very high employment densities as well as a historically dense transit network. Most American cities have widely dispersed employment, with less than 10 percent of jobs located downtown. Mass transit may only be efficient when employment densities are high.

Smart growth has been viewed by some as impractical when applied to entire urban areas. It is argued that only three of the nation's 400 urban areas have densities greater than 5,000 per square mile. For the remaining urban areas, even doubling density would reduce per capita auto driving by only about 5 percent, critics argue.

Since smart growth calls for few to no new roads, and an emphasis on mass transit, this could mean far more congestion. Smart growth solutions may help to decrease congestion, although it is clear that the two processes are closely related. Only as traffic congestion builds, it would seem, do alternative travel modes become more attractive. Politics play an inordinate role in transportation planning decisions. For example, supporters of the central business district seek to reduce the low-congestion advantage that suburban shopping and office centers have over downtowns by funding mass transit.

Trends at the beginning of the 21st century suggest that many of the industrialized cites are losing their central business population, their suburbs are growing rapidly, and urban densities are falling. This process of ex-urbanization will continue to require increased auto ownership and usage. It can expected that transit usage will remain stagnant or declining in many cities.

Economic trends in the world suggest a sobering picture of the world of transportation to come in future decades. Rapid growth of automobiles began in the United States due to rapid increases in wealth. As the average incomes of other nations increase, the desire for personal mobility may know no bounds.

II. Local Expert Opinion

A. Shane Hope

Smart Development for Traffic Solutions

By Shane Hope

How can we reduce traffic problems, while our communities continue to grow? One solution is "transit-oriented" development. This can make sense even when a community has little or no existing transit.

Transit-oriented development ("TOD") is simply a term for development that can easily be served by transit—typically, bus, rail, light rail, trolleys, or even ferries. This kind of development makes it easy for people to get places in a given area without using a car. In Washington, older neighborhoods in cities and towns, from Seattle to Wapato, are good examples. Some new developments, like Issaquah Highlands, are also being built for TOD.

Such development does not leave out cars. Many people still want or need cars for various reasons. But they don’t have to rely solely on cars. Instead, people can meet much of their daily working, living, and shopping needs by walking, biking, or riding some kind of transit.

"TOD" has homes, shops, schools, and workplaces located fairly close together and connected by streets and sidewalks. Parks, town squares, and greenbelts soften the space. When the development is completed, both transit and walking are convenient for most people.

Even if a community does not have transit now, planning for TOD could make future service easy. The supporting land uses, densities, sidewalks, and riders will already be there. That will result in lower costs to add the service later, when the time is right. If transit does not get added for many years, the community will still have had less traffic problems because people in theTOD neighborhood could make at least some of their trips on foot.

The opposite of transit-oriented development is sprawl development with single-use zones, for example, scattered single-family houses on large lots that are far separated from any shops, schools, or workplaces. Typically, in this model, the shops and workplaces would be scattered over a wide area too. A major problem with this pattern, which has predominated since the 1950s, is that it makes driving almost mandatory. Eventually, cars fill up the roads, while traffic becomes congested and auto emissions reduce air quality. This pattern is very difficult to change later, after everything has been built. With low land use densities, transit may never become feasible.

To allow more options, many communities are planing now for transit-oriented development. That way, they can encourage new development and traffic solutions at the same time.

Shane Hope works with Washington State Community, Trade and Economic Development

B. Other

III. Additional Resources

Please refer to the main Links section.

Authored and compiled by Nathaniel Trumbull. Last updated 02/09/2000.