The Influence of Regional Land Use and Transportation Patterns on Air Quality

      A Framework for Discussion

                                                 May 23, 2001

by Douglas R. Porter, President, The Growth Management Institute

This briefing paper has been  prepared for the Northeastern Illinois Planning Commission (NIPC). The Commission is working to develop a regional development plan for the Chicago metropolitan area. The regional development plan would serve as the foundation for the Chicago Area Transportation Study (CATS) transportation plan, which will be the basis for transportation investment decisions over the next 20 years and for reaching "conformity" with the State Implementation Plan for Air Quality.

NIPC is sponsoring preparation of a series of working papers to provide information about key development issues. Because nonattainment of air quality standards can significantly affect future federal funding of transportation improvements, the EPA Region 5 office in Chicago is contributing to this effort by supporting preparation of a working paper about the potential effects of regional development patterns on air quality, in cooperation with the Washington D.C. offices of U.S. DOT and U.S. EPA, and through a grant to the Growth Management Institute.

The briefing paper is based on nationally available data and studies. It provides background information for a discussion forum, cosponsored by NIPC and the EPA Region 5 office, which will identify significant factors in Northeastern Illinois' development and transportation patterns that may influence air quality, and add specific Chicago-area information for inclusion in the final working paper.

 Interrelationships of Land Use, Transportation, and Air Quality

The form of regional development influences travel decisions that people make. Certain patterns of development that have evolved over the past century encourage greater use of motor vehicles, which emit air pollutants and greenhouse gases that affect air quality. One of many factors that have led to these changes in urban development patterns is Americans' dependence on automobiles for travel, which enables low-density development. (Some other factors that have promoted dispersion include zoning policies that separate land uses, technologies such as refrigerators and computers that make homes more self-sufficient, and public subsidies of construction in unbuilt fringe areas.) As a result, metropolitan areas have expanded in size and decreased in density. Under these conditions, when a car is the only way to travel, we generate increases in miles travelled per day and rising car usage has contributed to unacceptable levels of air pollution in many metropolitan areas. Unless steps are taken to improve air quality, Federal rules call for cuts in transportation funding in metropolitan areas that do not conform to air quality standards.

Although there are many factors contributing to both increases in auto travel and air pollution, this paper focuses on the impact of regional development patterns on automobile use and the resultant impact on air quality. It is based on published data and studies that demonstrate the relationships between these factors of built and natural environments. It provides a foundation for the working paper that will identify the implications of these relationships for regional leaders as they deliberate the goals and character of a regional development plan for Northeastern Illinois.

Figure 1. Direct and Indirect Effects of the Built Environment

Taken from Our Built & Natural Environments:  A Technical Review of the Interactions between Land Use, Transportation, and Environmental Quality. U.S. EPA; Development, Community, and Environment Division (1808), Washington, DC, 20460.  EPA 231-R-01-002, January 2001.

Trends in Regional Land Use Patterns

The form of urban development has changed dramatically over the past century. In the early 1900s, most cities and metropolitan areas were compactly developed, with a single major center -- the central business district -- and major clusters of industries. People tended to shop for daily needs in their neighborhoods and many walked or took public transit to work.

Today, urban regions have developed many clusters of business and industrial activity over greatly expanded geographic areas. Between 1954 and 1997, urbanized land has almost quadrupled to about 74 million acres in the contiguous 48 states. From 1992 to 1997, the rate of urban land development more than doubled. Many urban areas have increased in size by 50 percent during the past 30 years, expanding much faster than the population. U.S. Census data for the 34 metropolitan areas with populations of more than one million show that urbanized land areas have averaged a growth rate of 2.65 times population increases (see Table 1). Much of this increase is contained in expanding suburban jurisdictions. Even metropolitan areas experiencing declines in population, such as Cleveland and Detroit, have continued to spread outward. Although there are signs that recent expansion of urbanized land may have slowed, and land consumption varies among metropolitan areas, most urban regions now incorporate large areas of relatively low-density development.

Table 1. Growth in Land Consumption Exceeds Population Growth, 1982-1996

Source: Calculated based on data from Texas Transportation Institute. Mobility Study (Urban Roadway Congestion: Annual Report 1998).

These changes in metropolitan form have occurred because of a variety of factors. The impacts of the automobile and roads on changes in urban form are only two of many social and economic factors that have encouraged low-density development during the post-war period. For example, new technologies in communications and transportation have facilitated expansion of metropolitan development patterns. Public policies, such as efforts to promote homeonwership through the G.I Bill of Rights and mortgage subsidies, have encouraged housing construction. Public investments in water and sewer infrastructure and other infrastructure have stimulated suburban development. And growing affluence, social change, and racial and ethnic concerns have led many Americans to seek large homes in desirable suburban jurisdictions, leaving central city cores to decline. The influence of these factors show up in the increases in automobile ownership, which have risen from 1.0 vehicle per household to 1.59 vehicles per household since 1960. 

However, reductions in monetary and time costs of travel have played a particularly important role in encouraging the dispersal of residential and commercial development. New highways funded in large part by federal programs have increased the accessibility of locations once remote or difficult to reach. As the relative importance of business transportation costs has decreased, outer locations became more attractive to industries and other employers. Highway improvements that made trucking easier also freed manufacturers from traditional rail and port centers. Furthermore, changes in commodity flows and freight handling (such as just-in-time delivery) have reduced dependence on central locations. And finally, firms with highly skilled workers tended to locate in areas most accessible by the regional highway network. All of these trends have increased the importance and amount of automobile travel in metropolitan areas, as explained in the next section.

Questions: How are these trends reflected in the Chicago region?

            • Is development becoming more dispersed and generating    lower densities?

            • Are jobs and households continuing to move out of the core to urban fringe locations?

            • Are public policies encouraging dependence on highways and cars?

Vehicle Travel Trends in Growing Metropolitan Areas

Vehicle miles of travel (VMT) in the United States increased 63 percent between 1980 and 1997. VMT growth has been particularly rapid in such fast-growing urban regions as Atlanta and Salt Lake City, but the Chicago area sustained a VMT increase of 79 percent from 1982 to 1996 on its freeways and principal arterials.

As shown in Table 2, the rate of VMT growth has significantly exceeded the rate of population growth during this period. VMIT growth also outpaced employment and economic growth. Furthermore, national VMT is projected to increase by 53 percent in the next 20 years, adding to traffic congestion and increasing travel delays.

The increase in VMT can be attributed to a variety of factors, including shifting demographic and market trends. The coming-of-age of the baby boom generation sharply increased the number of

            Table 2. Growth in Daily Vehicle Miles of Travel

 Exceeds Population Growth, 1982-1996

Source: Texas Transportation Institute, Urban Roadway Congestion, Annual Report 1998. Tables A-6 and A-7.

drivers in a short time and increased female participation in the work force put more drivers on the road during peak commuting periods. In addition, rising incomes and level fuel prices allowed families to afford more cars and drive farther. Changing development patterns have also contributed to the increase in VMT. Over the past 50 years, development has become more dispersed, land uses have become more segregated through zoning, and development designs are predominantly auto-oriented. Distances between destinations have increased and more people must use cars instead of walking, biking, or using public transit. As jobs and housing became increasingly segregated from one another, the average length of work trips increased by 23 percent (from 9.4 to 11.6 miles) from 1969 to 1995 across the nation. The share of people who drove to work alone increased while the share of people who carpooled, used public transportation, walked, or biked declined.

Adding road capacity by improving roads and constructing new highways facilitated changing development patterns. Added road capacity allowed vehicles to travel faster so people could elect to move farther out from the urban core. While work trip lengths increased by 23 percent between 1969 and 1995, work trip speeds were 34 percent faster.

Questions: How are these trends affecting transportation in the Chicago region?

            • Are demographic trends in Northeastern Illinois similar to national trends?

            • Is VMT per capita increasing in the Chicago area?

            • Are work trips increasing in length?

            • Is there evidence that highway improvements are inducing more travel?

Effects on Air Quality

Vehicle travel produces benefits in terms of mobility, convenience, and flexibility, but it also creates unintended environmental consequences. One important consequence is the impact of motor vehicle emissions on air quality. Vehicles emit pollution through fuel combustion (exhaust) during operation and fuel evaporation during and between periods of operation. Such pollution degrades air quality, impairs water quality through deposition of pollutants, and contributes to greenhouse gases and global climate change. 

Critical pollutants for which EPA has established air quality standards are carbon monoxide (CO), nitrogen dioxide (NO2), ozone (O3), sulfur dioxide (SO2), particulate matter, and lead. In addition, ozone is formed by other volatile organic compounds and oxides of nitrogen. Motor vehicles emit all of these but particularly a large amount of CO and the chemicals producing ozone. Vehicle travel also churns up large quantities of particulate matter from roads, especially on unpaved rural roads.

Figure 2. Highway Share of Air Pollutants Emitted, 1997

Note: percentages are based on anthropogenic emissions, except for PM-10, which includes natural emissions.
Source: U.S. Environmental Protection Agency. National Air Pollutant Emissions Trends, 1900-1997. 1999.

Air pollution degrades water quality by depositing nitrogen, metals, and polycyclic aromatic hydrocarbons (such as benzo[ghi]perylene). It also causes damage to building materials, agriculture, and visibility.

Vehicles also emit hazardous air pollutants known or suspected to cause cancer or other serious health effects or ecosystem damage. One 1991 study estimated the following health problems caused by motor vehicle emissions:

            • Roughly 50 to 70 million days of respiratory-related restrictions on individuals' activities;

            • About 852 million headaches from carbon monoxide;

            • Approximately 20,000 to 46,000 cases of chronic respiratory illness;

            • An estimated 530 cases of cancer from air toxins (although this risk of cancer is considered highly uncertain);

            • About 40,000 premature deaths in the United States.

The various impacts of air pollution are estimated by a 1999 study to cost $36.6 billion annually in health and property damage; other studies have estimated even higher costs.

Since 1970, motor vehicle emissions per mile have been decreasing as a result of emissions control systems and cleaner fuels. However, increasing VMT threatens to reverse this trend for emissions of carbon monoxide, sulfur dioxide, and particulate matter. In fact, the transportation sector is projected to be the fastest growing contributor to carbon emissions in the next 20 years -- an estimated increase of 47.5 percent from 1996 to 2020.

Questions:

            • How does the Chicago metropolitan area measure up to air quality standards?

            • If not, what actions are being taken to improve air quality?

            • Is there any evidence in the Chicago area of vehicle emission decreases?

            • Is there any evidence in the Chicago area of health-related effects of emissions?

            • How well do Northern Illinois residents understand the regulatory implications of continued nonattainment of air quality goals?

Development Patterns That Can Reduce Car Travel and Improve Air Quality

Developing more compactly, mixing land uses, and incorporating transit/pedestrian oriented design are approaches to development that may reduce car travel and improve air quality. Although the effects of specific development patterns on travel behavior and emissions are only partly understood, more intensive development, mixed uses, and safe pedestrian access can decrease trip lengths, support the use of transit, and increase pedestrian and bicycle travel. The result: lower VMT and improved air quality.

Compact Development: Compact development meets the space needs of development with less land area than typically used in growing suburbs. By using less land, compact development reduces trip distances and expands opportunities to travel by walking, biking, and public transit. Compactness can provide the "critical mass" needed to make transit feasible. Compactness need not require high-rise buildings or even lots of townhouses. Increasing the intensity of development by just 20 to 30 percent -- say by cutting one-third-acre lots to one-quarter-acre -- can use land much more efficiently without changing the character of the neighborhood in any way. Most communities could double development intensity without adversely affecting the market or quality of life. One well-known study determined that doubling residential densities promotes a decrease of 20 to 30 percent in VMT per capita.1[1]

In greenfield areas on the urban fringe, clustering development can achieve compactness while preserving open lands. Clustered neighborhood development, by grouping buildings closer together, can increase opportunities for walking, biking, and transit use. At the regional scale, developing on sites contiguous to already developed land can reduce travel distances.

Infill Development. Metropolitan areas can be more compactly developed by recycling existing sites and buildings, a trend underway in many American cities today. Infill of existing urban land builds on infrastructure systems already in place and revitalizes neighborhoods and older business centers. Infill also can occur on brownfield sites (abandoned or underutilized areas that may be contaminated, such as former manufacturing areas and railroad yards). In many cities, historic and architecturally distinctive buildings are being adapted for new uses. Recycling buildings and sites adds activities in highly accessible locations. Table 3 indicates that infill generated lower VMT per capita and reduced emissions of most air pollutants and greenhouse gases in the three cases studied.

            Table 3. Travel and Emission Indicators for Infill Site versus Greenfield Site

Source: Allen, E, Anderson, G, and Schroeer, W, “The Impacts of Infill vs. Greenfield Development: A Comparative Case Study Analysis,” U.S. Environmental Protection Agency, Office of Policy, EPA publication #231-R-99-005, September 2, 1999.

Mixed Land Uses: Mixing complementary uses within a neighborhood or a development site allows people to satisfy many travel needs in a small area. Having retail services within walking distance of residences, for example, generates higher levels of pedestrian travel and fewer vehicle trips than totally residential neighborhoods.[2] Mixing uses at employment and commercial centers reduces dependence on cars because (1) more people can walk to other uses during the workday and (2) that "walkability" increases the attractiveness of commuting by transit.[3] At a regional scale, achieving a balance of jobs and housing across the region allows more people to live near their work, thereby reducing travel distances.

Mixing uses requires careful siting and design of the various uses to ensure that all are compatible and easily accessible along attractive streets and pathways.

Transit- and Pedestrian-Oriented Design: Aspects of the built environment such as building orientation, street connectivity and design, and building design all contribute to the relative friendliness of areas to transit users, pedestrians and bicyclists. Neighborhoods with few streets connecting to other neighborhoods and nearby shopping centers require residents to travel longer distances to satisfy daily travel needs. Major streets with few crossing points and wide pavements act as barriers to foot and bike travel. Neighborhoods with few streets connecting to other neighborhoods and nearby shopping centers require residents to travel longer distances to satisfy daily travel needs. Major streets with few crossing points and wide pavements act as barriers to foot and bike travel. Areas lacking sidewalks, bike lanes, and safe crosswalks dissuade walking and biking, almost forcing people to drive instead. The design and placement of buildings along streets also can provide either a forbidding or a pleasant walking and biking environment.

By providing through streets that allow bus service and connecting pathways that make them accessible on foot, and by designing attractive and convenient settings for transit lines, compact, mixed-use development can promote greater use of transit. Extensions of transit service are more feasible if developing areas are designed to encourage transit use. Extending bus or rail service to new areas, adding faster and more attractive service within areas already served, and focusing new development and redevelopment around transit stations and centers all improve accessibility to transit. Transit needs to be accessible at both the origin and destination of trips for it to be competitive with car travel.

Questions: How are these methods of reducing travel and emissions being employed in the Chicago region:

·        What and where are the local success stories?

·        What more needs to be done?

·        Would the region’s local governments commit to alternative development policies and regulations at the local and regional levels to achieve better integration of transportation and land use?

·        What incentives/disincentives have worked in Chicago and other regions?

·        What incentives/disincentives would be effective in the Chicago region?

Conclusion

As regions seek to reach air quality attainment goals outlined in the Clean Air Act, the need to improve understanding of the relationship between air quality and development and transportation patterns becomes clear. Motor vehicle emissions currently account for a significan share of many air pollutant emissions. Increasing VMT threatens to undo advances in air quality made possible by a lowering of per-mile vehicle emissions and cleaner fuels. There is significant evidence that more compact, mised-use development focused around transit can reduce vehicle travel and air pollution from motor vehicles.

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