State officials have substantially increased spending on buses and rail projects in recent years. But it is clear that Caltrans plans to continue to feed the unsatiable demand for more freeway miles.
By the end of the year, one in every five miles of California highways will be under repair or improvement as part of a $7-billion transportation spending package.
"We are making our roads wider, faster, safer," Gov. Gray Davis said last month as he launched the $160-million widening of Interstate 15 in the Inland Empire. "We're keeping our freeways free. And we're getting California motorists moving again."
Even more transportation money is coming down the road now that voters approved Proposition 42, which is expected to pump $36 billion from the gasoline sales tax into transportation projects over 20 years.
But environmentalists and some transportation experts say further freeway widening plans are folly because of the impact of "induced demand." It is the theory that adding new freeway lanes only encourages more driving, offering only temporary traffic relief.
Under the induced demand theory, motorists who would normally shop close to home might make a longer drive, on a newly widened freeway, to a big mall across town.
"When you reduce the cost to access a place [by cutting the drive time] you encourage traffic to that place," said David Burwell, chief executive of the Surface Transportation Policy Project in Washington, D.C. "That is just straight economics."
But the theory of induced demand is not universally accepted.
"I just don't believe it," said David Hartgen, a professor of transportation studies at the University of North Carolina. He suggests that the added traffic on new freeway lanes primarily comes from drivers who previously used surface streets or alternate highway routes. New freeway lanes, therefore, ease congestion for an entire region, Hartgen said.
Last year, UC Davis engineers compared 18 freeway segments that were expanded in the 1970s with similar freeway segments that were not improved. The research found that the traffic growth rates for the improved and unimproved freeways were indistinguishable over a 21-year period.
The study concluded that other factors, such as demographic changes, population growth and the economy, play a bigger role in creating freeway gridlock.
"Our study finds no support for the claim that capacity expansion generates traffic disproportionately on account of the act of expansion itself," the study concluded.
