The Road More Traveled
Recent studies concur: new roads cause congestion
August 1, 1999 | By Kelly Thayer
Great Lakes Bulletin News Service
Government and private researchers across the nation are drawing the same conclusion: new and widened roads do not relieve congestion, but attract more cars and make it worse.
Three prominent studies in as many years chronicle the connection between new and wider roads and more driving, a phenomenon called "induced traffic" or "induced travel." The research concludes that building roads to solve congestion is a paradox that leaves communities more crowded, more polluted, with less open space and money for civic projects, and with no alternative for residents stuck in traffic.
How Could This Be True?
Anyone who has ever driven on a newly opened road knows the feeling of sailing along on smooth pavement, unimpeded by other vehicles. So how can a new stretch of asphalt cause congestion?
The answer is that everyone shares the same thought: "I can't wait to hit that new highway and zip to all the great places I've never had time to go to before."
The lure of quicker travel spurs more trips to places that before were not worth the hassle of fighting traffic. Other motorists use the time savings to drive farther to places that had seemed out of reach. Bus and train riders decide to climb back in their cars, which in turn can trigger public transit fare increases and cause even more passengers to become drivers.
Then developers take notice of rising "traffic counts," and put up sprawling businesses and subdivisions along the corridor. In the end, traffic clogs a road built to ease traffic.
"It's a real Catch-22," said David Kolata, a transportation specialist for the Environmental Law & Policy Center in Chicago. "New roads are built supposedly to relieve traffic congestion. Because these roads often attract more people, however, they actually make traffic worse. The end result is a perpetual construction machine that harms cities, taxpayers, the environment, and the very same suburban residents the new roads were meant to help."
Three Studies, One Conclusion
Concerned citizens hope the latest research can spur better transportation planning that emphasizes public transit rather than new roads and more congestion. The findings are compellingly consistent:
• In January 1999, Robert Noland, an analyst with the U.S. Environmental Protection Agency, reported results of a study on induced traffic using data from 1984-1996 for all 50 states. His conclusion: Several years after a road's space is expanded by 10%, traffic increases by 7% to 10%, filling up the added room.
• In November 1998, a report by the Surface Transportation Policy Project compared 15 years of data compiled by the Texas Transportation Institute on 70 U.S. metropolitan areas that added extensive new road space with those that did not. While the urban areas that added lanes spent roughly $22 billion more on construction, their traffic congestion afterwards was nearly identical to that of areas that did not expand their road systems.
• In 1997, University of California-Berkeley researchers studied data covering 30 urban counties in California from 1973 to 1990. They found that every 10% increase in road space generated a 9% rise in traffic over four years, eliminating the expected benefit of a new or widened road.
Quick to Build, Slow to Change
Despite the growing body of overwhelming evidence, most of the nation's highway planners continue to insist that roads satisfy demand, and never create it.
"Many transportation professionals will argue that induced travel only demonstrates that highway planners have put roads where people want to travel, that is, they have made accurate forecasts," said Mr. Noland.
In Michigan, the state Department of Transportation and most county road commissions still are locked in a race to build more roads faster than drivers can fill them up. MDOT is committed to spending $1.65 billion on new and widened roads over the next five years, and is studying plans to build new highways that would cost $2 billion more. (See related article on page 10).
MDOT did not respond to numerous requests for comment on its perspective regarding induced traffic.
Grassroots groups and an increasing number of local governments contend that induced traffic should be included in computer transportation models, which state and federal planners rely on to justify road-building projects.
They also say state policymakers should redirect road-building dollars to effectively combat congestion and create more livable communities. A new course for transportation in Michigan would encompass convenient and comfortable bus systems, commuter rail in the larger cities, space for bicycling and walking, and communities designed with strong downtowns that invite walking.
"MDOT consistently fails to properly weigh induced traffic and changes in land use that occur when new roads are built," said Julie Stoneman, director of land programs at the Michigan Environmental Council in Lansing.
"The result is more congestion and classic sprawl, subsidized by government road dollars,"Ms. Stoneman said. "It doesn't occur overnight. If it did, people would be quick to say, 'No more roads!'"
CONTACTS: Robert Noland, U.S. EPA, 202-260-2418; David Kolata, ELPC, 312-795-3703; Julie Stoneman, MEC, 517-487-9539; Kelly Thayer at the Institute, 231-882-4723 x13.