How Real Are Transit Gains? While transit advocates suggest there’s been a massive shift in travel behavior, those claims appear to be exaggerated.

Anthony Downs
Anthony Downs Former Brookings Expert

March 1, 2002

A new day has dawned in American travel: Transit is gaining sway over highway travel.

That’s what some public transit advocates have been claiming, based on a Surface Transportation Policy Project report in December 2000 that showed public transit boardings rose 4.8 percent in 1999 while vehicle miles of driving rose only 2.1 percent. Then, after reporting last November that there were larger percentage increases in transit usage than highway travel in 2000 and 2001, STPP said, “No precedent exists for this massive shift in travel behavior.”

A less partisan view shows these claims are exaggerated.

Getting exact and consistent information about transportation trends is not easy. The basic data on transit use are published by the American Public Transportation Association and the U.S. Department of Transportation’s Federal Transit Administration. Each agency produces multiple reports that do not always agree with each other. I have done my best to create a consistent database from these sources, but some extrapolation and interpretation remain necessary.

Two other background facts help put the discussion in perspective. First, a significant percentage of all public transit travel occurs in the New York City area and on its MTA, which accounts for 20 percent of all U.S. transit passenger miles and more than 27 percent of all unlinked passenger trips. So, although about 5 percent of all commuting is done by public transit, that fraction is only 2.2 percent outside New York.

Second, the absolute amount of total travel in private automobiles dwarfs public transit’s totals: In 2000, transit provided about 46.6 billion miles of movement while passenger miles traveled in the same year on highways totaled about 4 trillion—2.5 trillion in cars and another 1.5 trillion in small trucks and SUVs. That’s 86 times greater than passenger miles on transit. In fact, transit’s share of all passenger miles traveled in the U.S. from 1985 through 2000 averaged only 1.26 percent.

Consequently, even very small percentage gains in highway travel involve vastly larger absolute increases in miles traveled than much larger percentage gains in transit travel. In 1999, a year about which STPP said that “growth in public transit exceeds growth in driving,” total transit travel grew by about 1.7 billion passenger miles. But growth in car passenger miles was at least 51 billion miles and that in small private vehicles (excluding motorcycles and buses) was at least 80 billion miles. (These totals may be low because I adjusted the official data downward to reflect STPP’s estimates of percentage gains.) Thus, the annual increases in highway passenger miles traveled in 1999 exceeded those in transit passenger miles by ratios of either 31 or 48 to 1. That hardly indicates that growth in transit was exceeding growth in driving.

True, transit usage has had a notable recent growth spurt. Between 1985 and 1995, transit usage declined in every year but 1989, falling overall from 8.6 billion trips to 7.8 billion, or by 10 percent. Then in 1996, transit usage began rising, reaching 9.3 billion trips in 2000—a gain of 20 percent over 1995. But driving travel was also increasing in that period. Although auto gains were smaller in percentage terms–11.9 percent–they were massively larger than transit gains in absolute terms: 425 billion passenger miles versus 9 billion. Thus, even during this period of transit’s resurgence, 98 percent of the increase in total passenger miles traveled occurred on highways.

Transit advocates may hope that if transit continues to grow faster than highway travel in percentage terms, transit may eventually attain a much greater share of total passenger miles. But transit has two handicaps in this “race.” It starts with a very low share—1.15 percent in 2000—and total passenger travel on highways is rising all the time.

A simple simulation model shows that if both types of travel start with their 2000 absolute levels, and transit usage increases 5.36 percent per year (its highest recent annual rate of gain) and highway travel gains only 1 percent per year, then the share of transit in total ground passenger miles would not reach 5 percent until 2036. Even if highway driving did not rise at all while transit did, transit would not reach 5 percent of all ground passenger miles until 2029. If transit usage rises at its actual compound annual growth rate from 1995 to 2000 (3.74 percent) and highway travel rises at its similar rate (2.27 percent), transit would not reach a 5 percent share until the next century.

Improving and expanding the nation’s public transit systems and upgrading their images are worthwhile goals that deserve significant effort and intensive promotion. And all special interest groups have a “natural” tendency to overemphasize both the virtues and success of their causes in order to gain attention. But it is also a good idea to retain a statistically accurate and objective understanding of the facts when dealing with such complex and controversial issues, especially those that involve billions of taxpayer dollars.