What accounts for the marked differences in transportation expenditures in different places? Our analysis indicates that the biggest effect comes from the spread-out development pattern commonly called sprawl.

The relationship between sprawl and expenditures on transportation can be seen both through the statistical analysis described in the following paragraphs and by a cursory look at the country’s most expensive metropolitan areas (see Table 2). Nearly all the places at the top of the list are sprawling metropolitan areas that offer their residents relatively few transportation choices. Houston, Atlanta and Phoenix in particular have been marked in recent decades by extraordinary growth in both their physical boundaries and the extent of their highway networks.

In contrast, the places where households spend the smallest portion of their budgets on transportation are more likely to have a compact form and a good public transportation system. Chicago and Boston fit this profile, as do neighborhoods such as Westwood and Belmont Shores in the Los Angeles metro area, and North Beach and Rockridge in the San Francisco metro area. We could expect similar savings in similar neighborhoods across the country, from Silver Spring, Maryland to Montclair, New Jersey.

This intuitive picture is borne out by a statistical analysis comparing household transportation expenditure data to a number of geographic and demographic factors. For this analysis, we compared data from the Consumer Expenditure Survey to socio-economic, land use, and transportation data gathered by our researchers.¹ Some factors, such as household size, were found to have no significant effect on household expenditures. Others, especially the land use pattern that constitutes sprawl, were found to have a powerful effect.

What Is Sprawl?

To determine the exact relationship between sprawl and personal costs, we compiled several measures of sprawl developed by STPP and affiliated researchers². This composite measure summarizes the efficiency of land use in metropolitan areas in terms of several different indicators:

Mix of Land Uses. Sprawling metro areas tend to segregate housing, workplaces and stores from one another in single-use districts. Jobs are far away from homes, and residential neighborhoods contain housing but no jobs or stores.

Clustering and Centeredness. Sprawling metro areas spread subdivisions, office parks, and malls over the landscape in a relatively even layer. Few town centers exist that might make walking trips between various destinations feasible. Less sprawling metro areas have more concentrated downtowns as well as smaller town centers where residents, employees, and shoppers can walk between various destinations.

Compactness. Sprawling metro areas generally have fewer homes per acre, and all types of development tend to be more spread out in the city, inner suburbs, and outer suburbs. This simply puts everything further apart. Compact metro areas have, on average, more development in less space.

The Impact of Sprawl

As shown in Figure H, the places with more characteristics of sprawl tend to be places where households use more of their budget to pay for transportation. Less sprawling places, those with more efficient land use, tend to have lower costs. This analysis shows almost 50 percent (R2 = .482) of the variation in the share of household expenditures devoted to transportation is explained by sprawl. This analysis excluded Anchorage because of a lack of land-use data. For a more detailed description of the sprawl factors used, see Appendix A.

The three metro areas where families use the highest portion of their spending dollar on transportation (Houston, Atlanta, and Dallas) are among the four most sprawling metro areas surveyed. The places with the lowest portion of household budgets spent on transportation, New York and Honolulu, also exhibit the least sprawling development patterns. Households in the one-third of metro areas that are the most sprawling devote about 20 percent more of their expenditures to transportation than do households in the one-third of the areas that are the least-sprawling. In the one-third of metro areas with more sprawl, households spend more on buying automobiles (36.5 percent more), buy more gasoline (13.8 percent), and spend more on miscellaneous automobile expenses (12 percent). This is not a function of higher income, these areas actually had slightly lower average incomes than less sprawling places. As a result, the average American family living in a highly sprawling area pays roughly $1,300 more per year in transportation expenses.

Why Sprawl Drives Up Costs

Greater distances between destinations and a lack of transportation choices means households have little choice but to own and operate a number of automobiles. This makes sprawl expensive.

Distance necessitated by sprawl means higher spending on gasoline and upkeep of vehicles. For example, the two metro areas ranked as the most expensive, Houston and Atlanta, both scored poorly in the sprawl measure, and are also the two metro areas where people drive the farthest each day. The average Houstonite travels 38.4 miles in a car per day, while the average Atlantan travels 36 miles by car each day.

But distance drives up costs in more significant ways. Sprawl means more trips are made by car, because long distances often make automobiles the only practical way to travel. Many studies have shown that when destinations are far apart and homes are located far from stores, businesses, schools and other destinations, more trips are made by automobile.³ Sheer distance often precludes the most inexpensive forms of transportation, walking and bicycling. In addition, communities with a uniform spread of subdivisions, office parks, and strip malls require more driving than regions that have focused development around town centers. In such sprawling areas, even traveling across the street between stores can mean a car trip across a couple of parking lots and a major road.

Fewer Choices Mean Higher Costs

The problems presented by distance are compounded by a lack of transportation choices in sprawling areas. Sprawling locations usually lack frequent bus service, continuous, pleasant sidewalks, or safe bike lanes.

To allow us to compare family transportation costs with the degree of transportation choice available in a given region, our research team developed a "Transportation Choice Ratio" for 27 of the metro areas covered by this study. This ratio compares the relative supply of public transportation to roads in a metropolitan area. It is calculated by dividing the miles of public transportation service per household offered over the period of one hour by the number of lane miles of freeways, expressways and principle arterials per household in that area.⁴

A low Transportation Choice Ratio means that an area’s road network dwarfs its public transportation system. A high Transportation Choice Ratio means an area offers a relatively high level of transit service in relation to the size of its road network. By this measure, the Kansas City metro area offers the lowest level of transportation choice, with a ratio of just 0.2 miles of transit service per mile of roadway. Not surprisingly, New York City offers the most choice, with a ratio of about 4.6 miles of transit service provided each hour for each mile of major roadway.

The Transportation Choice Ratio is highly correlated to the sprawl measure.⁵ Transit cannot serve sprawling areas effectively, and the absence of choice in sprawling areas can force families to own multiple cars, and then use their cars for almost every trip. This drives up household transportation expenditures.

This is illustrated by a direct comparison of the Transportation Choice Ratio with the Consumer Expenditure Survey figures. Places with less choice (a low ratio) tend to be places where households spend more on transportation. (See Figure I). Even when New York, with its extraordinary transit use, is taken out of the equation, the relationship remains strong. Places with few transportation choices have higher transportation expenses.

Transportation Choice: An International Comparison

European, American, and Asian metro areas provide a very different balance of transportation options, and as shown in Chapter Two, transportation expenses vary markedly. While the median US transportation choice ratio is 0.47, European metro areas average a ratio of more than four to one, while Asian metro areas provide far more transit capacity than road capacity. In terms of the Gross Regional Product (GRP), Americans spent 38 percent more on transportation than Europeans.

Since so many factors come into play in cross-continent comparisons, we chose to also compare three metro areas that are geographically close but offer very different options to their residents: Detroit, Chicago, and Toronto, Canada, just across the border. In 1990, Detroit used fifteen percent of its GRP on transportation, while Chicago used about twelve percent, and Toronto used seven percent. Toronto’s share of total expenses as measured by the GRP is less than half of Detroit’s. The transportation balance⁶ is markedly different in the three metro areas. Detroit provides far more roads per capita than transit, having a ratio of 0.27; Chicago has a ratio of 0.90, and Toronto shows a ratio of 4.30.

Factors with Little Influence on Transportation Expenses

In preparing this report, the authors examined several types of expenses that generate attention when transportation costs are compared: the variation in gas taxes, gas prices and automobile insurance in different parts of the country. While these factors have gotten a lot of public attention and sparked public outrage, they actually account for only a small portion of the variation in overall transportation expenditures across metro areas. In the fourteen metro areas with higher expenses as recorded by the Consumer Expenditure Survey, gasoline (including taxes) cost an average of eight cents less per gallon than in the less expensive metro areas. Among the high expense areas, average insurance costs measured on a statewide basis were almost $20 per year less than in the rest of the sample.⁷ So while gas prices, gas taxes, and insurance rates have all been targets of consumer complaints and even political campaigns in recent years, they do not appear to account for the differences in transportation expenditures between metro areas.

Putting the Transportation Burden on Families

Sprawling places with a heavy reliance on roads tend to privatize transportation expenses: While the government builds the roads, private individuals buy, fuel, and maintain the automobiles that drive on them. As demonstrated in Chapter One, automobile ownership and operation are the biggest items in the household transportation budget. The popularity of large, expensive sport-utility vehicles and minivans may in part reflect the need for private cars to serve for all types of trips.

In places with a compact and convenient layout, where shops, schools and homes are closer together, there are other, less expensive, ways to get around. Walking and bicycling, both extremely inexpensive travel modes, are much more practical, and good transit tends to be more available as well. If some family members get to work or school on the train or by foot, the family may be able to own fewer cars. Or it might be more practical for the family’s "second car" to be smaller, less expensive, or both.

Public transit allows individuals to pay a fare that reflects just a small share of the purchase, fueling, and maintenance costs of the buses and rail cars that they ride. While residents in these areas may pay slightly higher taxes to help pay for the transit service, this relatively minor increase in taxes is greatly outweighed by the large savings they are able to achieve in their overall transportation budget (see box, page 14). A recent economic analysis concluded that "the public realizes five dollars in cash savings for each tax dollar invested in transit services. These are the costs of owning, operating and accommodating automobiles that several million Americans avoid with the help of transit services."⁸ The evidence presented in this chapter suggests that sprawl transforms driving from a convenient choice into an expensive necessity.