TTI Study: Nation’s Traffic Congestion Growing Worse

Fri October 10, 2003 - Southeast Edition

Traffic congestion nationwide continues to worsen, but the burden would be far greater without a handful of remedies already in place, according to the nation’s longest running study of traffic jams.

Researchers have spent years refining their knowledge of America’s traffic problem. This year, those same experts for the first time have a clearer understanding of the magnitude of the problem facing urban America and what will fix it.

The annual Urban Mobility Report, published by the Texas Transportation Institute (TTI), measures the effect of five congestion remedies in the cities where they are being used. Specifically, the study illustrates the effect of public transportation service, bus and carpool lanes, and three types of roadway operating efficiencies — traffic signal coordination, freeway incident management (clearing crashes and disabled vehicles) and the use of freeway entrance ramp meters (signals that regulate traffic flow onto the freeway). Estimates of the effect from those improvements are reflected in this year’s study, which uses 2001 data, the most recent available.

As in years past, the study looks at 75 cities measuring factors such as hours of travel delay per person and the Travel Time Index — a measure of the extra travel time per trip. But with additional analysis, researchers Tim Lomax and David Schrank have produced a new set of mobility measures that gauge traffic problems and potential solutions.

As an example, researchers used the national average 25-minute one-way commute trip to work and found that a combination of all five remedies reduced the total amount of annual congestion delay per commuter from 58 hours to 50.5 hours. Complete use of the five remedies in all 75 study cities would cut that commute trip delay to 45 hours.

Those findings tell the researchers two things. “First of all, we can save a significant amount of time with solutions we now have available, and we can do so at a cost that’s very low in comparison to what it costs to build a transportation system,” Lomax said. “But second, even with widespread use of cost-effective solutions, we need to add more capacity, manage the demand and seek improvements in land development patterns as well.”

The operational solutions — ramp meters, incident management and signal coordination — account for a delay decrease for all peak period trips from 26 hours in 2001 to 24 hours. This despite the relatively low deployment rates — from zero for some treatments in some cities to averages between 20 and 60 percent nationally. The delay for these trips — which includes commute trips, shopping, school, medical and freight travel — is up four hours from 1996, and is an increase of 30 minutes from 2001.

If the same remedies were put to use on all of the major roads in all 75 of the study cities, total travel delay would fall to 22 hours per person — a 15 percent improvement and equal to the delay in 1996, buying a five-year improvement in congestion growth.

Researchers also examined the effect of public transportation systems in two ways. The annual effect of eliminating public transportation service in all 75 cities, while not necessarily a realistic alternative, would have the effect of adding the equivalent of one billion hours of annual travel time. If the mobility provided to the nation’s eight billion daily public transportation riders were included in the Travel Time Index, the 2000 national average value declines from 1.39 to 1.34, the equivalent of five years of congestion growth.

While the nation’s traffic gridlock problem is in fact growing, Lomax and Schrank contend that it would be growing even faster were it not for the various remedies measured for the first time this year.

“Congestion is worsening, no doubt about that,” Lomax said, “but it would be a much greater problem if not for these and other remedies. Daily commuters may notice that their trip times are more reliable on some public transportation routes or roadway corridors where operational treatments have been deployed. This year’s study reinforces our belief that the best solution is actually a combination of solutions. Each city needs its own ’bag of tricks’ to address this growing problem.”

In addition to offering the new rankings, the 2003 report provides fresh statistics to illustrate a pair of familiar trends:

• The cost of congestion continues to climb. Nearly six billion gallons of wasted fuel and four billion hours of lost productivity resulted from traffic congestion in 2001, costing the nation $69.5 billion, nearly $5 billion more than the previous year.

• The extra time needed for rush hour travel has tripled during the last two decades. The national average Travel Time Index for 2001 was 1.39, meaning a rush hour trip took 39 percent longer than a non-rush hour trip. The national average in 1982 was only 1.13.

“Any objective analyst of the situation would say America needs more infrastructure capacity in all modes of transportation to keep pace with a growing population and economy,” said ARTBA president and CEO Pete Ruane. “If you don’t add capacity — and we really haven’t in a significant way over the past 30 years — the result is congestion. Since 1970, energy consumption has increased 42 percent, the U.S. population has increased 33 percent, vehicle miles traveled increased nearly 150 percent, but new highway capacity has only increased six percent.”

“It is also evident that we are not providing the level of public investment necessary to maintain the existing highway, bridge and transit system, much less invest in needed new capacity,” Ruane said.

“There are a number of things that Congress can do to help alleviate traffic congestion,” he noted. “Number one is significantly increasing highway and public transit capital investment. No revenue raising option should be taken off the table — including the federal gas tax. Congress should also support new ways to add highway and transit capacity. Other solutions include improved handling of traffic incidents to clear roadways quickly, increased use of synchronized traffic signalization, ’smart road’ technologies to increase traffic flow and completely closing roads that need repair to traffic, when possible, so that contractors can get in and finish the work as fast as possible.”

The 2003 Urban Mobility Study is sponsored by the American Road and Transportation Builders Association’s Transportation Development Foundation and the American Public Transportation Association. A consortium of 10 state transportation departments has participated in the methodology enhancements.

The Texas Transportation Institute, based at Texas A&M University, is the nation’s largest university-affiliated transportation research agency in the nation.