Eric Jaffe, in CityLab, recently reported that Caltrans “admitted” that expanding highways increases traffic by posting a policy brief on the subject of induced demand to its website. He called it a rare admission from a state department of transportation.
State DOTs, as the country’s road builders, have usually responded to congestion, and even safety concerns, by expanding and widening roads, expecting that more lanes will solve problems caused by too many people wanting to drive on them at the same time. But research has shown that making it easier and quicker for people to drive somewhere just encourages more driving. By linking to the policy brief, “Increasing Highway Capacity Unlikely to Reduce Congestion,” [PDF] Caltrans is openly acknowledging the connection between building new capacity and more driving.
But linking to a policy paper doesn’t mean that California will stop building roads altogether.
There is still plenty of pressure to keep building roads—from rural areas that want wider highways, for example, to local areas that tax themselves for new highway expansions (as Placer County is considering doing).
Meanwhile the State Transportation Improvement Program, which is the blueprint for investing in highways in California, contains locally preferred projects including highway expansions, and the California Transportation Commission continues to approve funding for them.
Streetsblog reached out to Steven Cliff, Caltrans’ assistant director of Sustainability, to find out whether the department really has come to accept the concept of induced demand–that if you build more highway miles, more miles will be driven. Cliff said, in short: yes. “It’s pretty settled science that capacity expansion induces demand,” he said. “We know that while it relieves traffic in the short term, there’s pent-up demand that suggests it just fills up again in short order. There’s ample evidence that if you lower costs, demand increases.”
And what does that mean for the department formerly known as the state highway department? (Under Caltrans’ new mission and vision, it’s now the department that “provides a safe, sustainable, integrated and efficient transportation system to enhance California’s economy and livability”–not just highways for cars.)
Caltrans, within its new strategic management plan, developed goals to reduce vehicle miles traveled (VMT). “We can’t keep using single occupancy vehicles as our primary way to get around,” said Cliff. “Arguably, we’re not moving people efficiently now,” he said, and it will only get worse as California’s population increases.