Rail Transit Won't Reduce Congestion

September 30, 2003

Publication by the Texas Transportation Institute (TTI) of its 2003 urban mobility report on September 30, 2003, led the transit lobby to make false claims about the role transit can play in relieving urban congestion. The American Public Transportation Association claims that the report says that "more public transportation is needed to relieve traffic congestion". In fact, the report says no such thing.

TTI, which is part of Texas A&M's engineering program, has published its annual urban mobility report for over a decade, and the latest report tracks highways and driving in each of seventy-five urban areas from 1982 through 2001.

This year, TTI added a new feature: an evaluation of how bad congestion would be if public transit were somehow eliminated. The Institute made the unrealistic assumption that, without publicly supported transit, everyone who now rides transit would start driving everywhere where they now go by transit. Since a large share of transit users in most cities are people who can't drive, and since privately operated transit services would quickly replace many public transit routes, this is absurd.

Based on this assumption, TTI calculated that transit greatly reduces urban congestion. Even this is unlikely in most urban areas. When the main Los Angeles transit agency went on strike for a month in 2000, few could discern any increase in congestion. Except in a handful of major urban areas (mainly New York, Boston, Washington, Chicago, San Francisco, and Philadelphia), transit carries too few people to make any difference to congestion outside of downtown areas. This makes transit really just a subsidy to downtown densities.

Even if TTI's calculations are correct, the report says absolutely nothing about whether further investments in transit will reduce congestion. This is especially striking, because the report DOES calculate that further investments in other programs can reduce congestion:

  • Freeway ramp metering currently saves motorists 73 million hours a year, and adding it to congested freeways that do not now have it could increase the savings by nearly 200 million more hours;
  • Traffic signal coordination, which TTI calls "one of the most cost-effective tools to increase mobility" on signaled roads, could save motorists an added 17.2 million hours a year;
  • Incident management -- a coordinated effort to quickly remove stalled vehicles and other highway obstructions -- could save motorists 100 million hours a year.

TTI also examined high-occupancy vehicle (HOV) lanes but could not find evidence that they had significantly reduced congestion in most areas. TTI said this was partly due to a lack of data, but in fact many HOV lanes do not carry enough multi-passenger vehicles to justify their use. TTI did not consider the effect of turning HOV lanes into high-occupancy/toll (HOT) lanes, as proposed by the Reason Foundation and others.

In contrast to its statements on ramp metering, signal coordination, and incident management, the TTI report makes no statements about the effects of investments in transit. Or does it?

A close look at the ranking of regions over the last two decades reveals that congestion grew fastest in those regions that invested mainly in rail transit. By contrast, regions that invested heavily in highways had much slower congestion growth, even in the case of many regions that grew faster than the rail regions.

To see this relationship, you can download the basic TTI data in an Excel spreadsheet summarized on the American Dream Coalition web site. You should also download an explanation of all the columns in the spreadsheet. This spreadsheet shows population growth, growth of the "travel time index" (the institute's best measure of congestion), and other pertinent data for all seventy-five urban areas.

Although you can sort the spreadsheet in any order you wish, it is currently sorted by the growth of the travel time index. The travel time index is a measure of how long it takes to get somewhere during rush hour compared to other times of the day. If, in uncongested conditions, it takes an hour to get somewhere, and it takes 1.5 hours in congested conditions, then the travel time index is 1.5. If the index in 1982 was 1.1 and in 2001 it was 1.4, then the growth is .3 or, as the institute puts it, 30 points.

The striking result is that nearly all of the ten urban areas with the fastest congestion growth are rail cities. Two of the areas, Seattle and Minneapolis-St. Paul, did not start building rail lines until the end of the 1982-2001 period, but both adapted anti-highway policies by the early 1990s.

In contrast, fast-growing communities such as Orlando and Houston all have low rates of congestion growth, mainly because they invested in new highways rather than rails. Las Vegas is particularly striking. Despite being the nation's fastest growing major urban area, new roads allowed it to have only the seventeenth-fastest growing rate of congestion.

Las Vegas also improved its bus service by contracting out buses to private operators, which led to a doubling of the region's transit market share of commuters in the last decade. No other urban area has been able to double transit's market share in this time period, and certainly none that focused on rail transit. About half of all rail cities, including Baltimore, Chicago, Cleveland, Dallas-Ft. Worth, Hartford, Philadelphia, Pittsburgh, St. Louis, and Washington, actually had fewer transit commuters in 2000 than 1990 despite having tens to hundreds of thousands of new commuters.

There's a good reason why rail transit doesn't work: It is slow and inconvenient. Light-rail lines average around 20 to 25 miles per hour. Heavy-rail and commuter-rail lines are a little faster, but when the time required to get to and from rail stations is taken into account, rails just cannot compete against the door-to-door convenience of autos for must urban trips.

New rail lines often get a boost in riders over their bus predecessors because the rail cars operate more frequently and stop less frequently (thus going faster) than the bus services they replace. But operating buses more frequently with fewer stops (sometimes called "bus rapid transit") will also boost ridership -- and cost far less.

Compared to buses or highways, rail is extremely expensive. Light rail typically costs as much to build as a four-lane freeway (see typical costs). Yes, as shown in this file (Excel spreadsheet) for almost every operating rail line in the country, the average American light-rail line carries as many people as just one-third of a freeway lane. The only heavy-rail lines that carry more people than a single freeway lane are the New York City subways.

If half of rail riders were former auto drivers--which is optimistic--urban areas would need to build six miles of light rail, at twenty-four times the cost, to get the same congestion relief provided by one lane mile of freeway.

If rail transit won't reduce congestion, what will? Some answers are provided by the TTI report, which evaluated the effects of expanding freeway ramp metering, traffic signal coordination, and incident management systems to all urban areas.

Freeway ramp metering, which puts traffic signals at on ramps, seems annoying, but it can save motorists' time by smoothing out freeway flows. The institute says that ramp metering now saves motorists 73 million hours per year, and this could be quadrupled if it were implemented on more congested freeways.

Traffic signal coordination allows motorists to drive at a steady rate of speed without stopping at each signal. The Texas report calls it "one of the most cost-effective tools to increase mobility" on roads that have signals. Yet more than half the major roads that could use signal coordination do not yet have it.

Another congestion program, called incident management, aims to quickly remove crashed and stalled vehicles and restore free-flowing traffic. Half of all congestion is due to such incidents. About half of all urban areas had incident management programs in 2001, which the Texas report says saved motorists more than 100 million hours.

In contrast, data in the TTI report suggest that HOV lanes haven't been very effective at reducing congestion. They don't particularly encourage people to carpool, so they only work when there are already enough multi-passenger vehicles for them to succeed. However, converting HOV lanes to high-occupancy/toll (HOT) lanes, as suggested in a Reason Foundation report by Robert Poole and Ken Orski, could make these lanes work much more effectively. Like HOV lanes, HOT lanes allow high-occupancy vehicles to travel for free, but low-occupancy vehicles could also use them provided they paid a toll.

On one hand, the TTI report clearly showed that low-cost programs such as ramp metering, traffic signal coordination, and incident management can reduce congestion without building new roads. On the other hand, the report did not evaluate rail transit, but makes it clear that rail cities tend to have the fastest-rising congestion. This information does not support the rail-transit lobby's contention that diverting more federal gas taxes from roads to transit will help reduce congestion.

In the past the Texas Transportation Institute's mobility reports were sponsored by state departments of transportation. This year, the American Public Transportation Association, which represents most transit agencies as well as rail transit engineering and construction firms, was a major co-sponsor. The group issued its press release urging more spending on transit within minutes of the Texas Transportation Institute's release of its report. It is disappointing that the Institute, which in the past has presented its data in an objective manner, has allowed itself to become a tool of the rail-transit lobby.