Widening highways doesn’t fix traffic. So why do we keep doing it?
Interstate 710 in Los Angeles is, like the city itself, famous for its traffic. Freight trucks traveling between the city and the port of Long Beach, along with commuters, clog the highway. The trucks idle in the congestion, contributing to poor air quality in surrounding neighborhoods that are home to more than 1 million people.
The proposed solution was the same one transportation officials across the country have used since the 1960s: Widen the highway. But although adding lanes can ease congestion initially, it can also encourage people to drive more. A few years after a highway is widened, research shows, traffic — and the greenhouse gas emissions that come along with it — often returns.
California’s Department of Transportation was, like many state transportation departments, established to build highways. Every year, states spend billions of dollars expanding highways while other solutions to congestion, such as public transit and pedestrian projects, are usually handled by city transit authorities and receive less funding.
Over the next five years, states will receive $350 billion in federal dollars for highways through the infrastructure law enacted last year. Although some have signaled a change in their approach to transportation spending — including following federal guidelines that encourage a “fix it first” approach before adding new highway miles — many still are pursuing multibillion-dollar widening projects, including in Democratic-led states with ambitious climate goals.
The Biden administration has suggested that states should be more thoughtful in their solutions to congestion. Sometimes widening is necessary, Transportation Secretary Pete Buttigieg said, but other options for addressing traffic, such as fixing existing roads or providing transit options, should be considered. “Connecting people more efficiently and affordably to where they need to go,” he said, “is a lot more complicated than just always having more concrete and asphalt out there.”
Some communities and government officials are pushing back on widening plans. In Los Angeles, this opposition had an impact. After $60 million was spent on design and planning over two decades, the Route 710 expansion was canceled in May.
“We don’t see widening as a strategy for LA,” said James de la Loza, chief planning officer for Los Angeles County’s transportation agency.
It remains to be seen if the cancellation is the start of a trend or an outlier. Widening projects are still in the works for highways in Texas, Oregon and Maryland, to name a few. New York City is even considering rewidening the traffic-choked Brooklyn Queens Expressway.
LOS ANGELES
A change in approach to congestion
The cancellation of the Route 710 expansion came after California learned the hard way about the principle of “induced demand.”
In 2015, a $1 billion project to widen a 10-mile stretch of Interstate 405 through Los Angeles was completed. For a period, “congestion was relieved,” said Tony Tavares, director of Caltrans, short for California’s Department of Transportation.
But that relief did not last. Rush-hour traffic soon rebounded, he said.
When a congested road is widened, travel times go down — at first. But then people change their behaviors. After hearing a highway is less busy, commuters might switch from transit to driving or change the route they take to work. Some may even choose to move farther away.
“It’s a pretty basic economic principle that if you reduce the price of a good then people will consume more of it,” said Susan Handy, a professor of environmental science and policy at the University of California, Davis. “That’s essentially what we’re doing when we expand freeways.”
The concept of induced traffic has been around since the 1960s, but in a 2009 study, researchers confirmed what transportation experts had observed for years: In a metropolitan area, when road capacity increases by 1%, the number of cars on the road after a few years also increases by 1%.
For years, critics of the Route 710 plan had voiced concerns that the widened highway would lead to more greenhouse gas emissions and the bulldozing of the communities around it.
In late 2020, the Environmental Protection Agency ruled that the widening plan violated the federal Clean Air Act, and officials paused the project. Then last spring, Caltrans canceled the project altogether. Tavares said it was “probably the most significant” cancellation in the agency’s history.
Caltrans is considering alternatives to address traffic on the Interstate, including moving freight to a rail line.