Why widening highways doesn’t reduce traffic congestion » Yale Climate Connection

California is proud of its climate leadership. The nation’s work on transportation—its largest source of emissions—is no exception. Its electric vehicle policy has been adopted by other states across the country. Sacramento lawmakers have also taken ambitious steps to reduce car use entirely, enacting regulations designed to reshape neighborhoods and encourage walking, biking and public transportation.

But reality often fails to realize this vision. In particular, communities across the state continue to invest heavily in highway expansion projects that undermine efforts to change the way people travel. Due to a phenomenon known as “induced travel,” these programs cause Californians to spend more time driving, not less.

Amy Lee is a postdoctoral scholar at the UCLA Transportation Institute who has been studying the politics of induced travel and highway expansion in California for several years. Yale Climate Connect spoke with her to learn more.

This interview has been edited and condensed.

Yale Climate Link: Can you give me a high-level overview of induced travel? How does it work?

Amy Lee: Therefore, the biggest factor people consider when deciding how to travel is cost. It’s not just a matter of money, it’s also a matter of time – time is a very, very important factor in our travels. When a road is congested, traveling on that road can take a long or unpredictable time, which can discourage people from using the road.

Highway widening is a bit like selling tourism. It attempts to reduce congestion by expanding road supply and reducing travel time costs for travelers using the roads. Suppose traffic jams prevent me from going to a restaurant 20 miles away that I really like, but the widening of the highway allows me to go there more often. Or I might choose the doctor in the next town over the one near me.

Due to the expansion of highways, we have rearranged our travel patterns, and the resulting new ways of driving are what we call induced travel. Studies show that congestion returns to previous levels about five to 10 years after highway widening due to induced travel.

YCC: Is this something that was discovered recently, or have we known about it for a while?

plum: We've been measuring this for a long time. It has been observed for at least 100 years and has been measured using increasingly sophisticated statistical methods since the 1970s and 1980s.

YCC: Therefore, highway expansion is clearly problematic from a transportation planning perspective. Can you talk more about how it impacts climate change?

plum: There are several ways. One is that the materials involved in the actual construction of highways and roads—concrete, aggregate, asphalt—are extremely carbon-intensive. Highway expansion emits large amounts of carbon during production.

Then once the highways are built, we develop communities around them, building further along these highway corridors, which creates car use, which leads to more emissions. Currently, cars run primarily on fossil fuels, and it looks like they will continue to do so for a long time to come.

Highway expansion can also make transportation in urban communities more difficult. I live in a city with classic freeways that cut right through the city center, taking suburban commuters into the metropolitan core and separating communities like mine from the city center. To get to the city center from where I live, you have to cross the highway twice. Researchers have been doing really cool research on how this hinders walking and biking. As roads expand, not only will your shopping mall or doctor's office be further along the highway, but even if you're only walking a short distance, getting around your own neighborhood without driving will become even more difficulty.

YCC: I imagine highway expansion would also come with a huge opportunity cost. They're expensive, and that's money that wouldn't be spent on anything else.

plum: Absolutely. It’s not that we’re not building transport and cycling infrastructure everywhere because of a lack of funding. In California alone, about $30 billion is expected to be spent on transportation in the next fiscal year—an astronomical amount. So we have money; it's just how we choose to spend it. Historically, and even today, a large portion of that has been devoted to highways and freeway expansion.

Transportation people like to say, “Oh, but we can't just move money around because every project's funding doesn't come from one big pot.” It's true; the legislation creates a lot of pots. If we want to change these policies, we can. I won’t deny how difficult it is, though.

YCC: For your Ph.D. In your paper, you interviewed dozens of people involved in California's highway program. What did you learn about how they view induced travel and climate change?

plum: There are various ideas about induced travel. Some argue that this is a priority that needs to be addressed in policy and programmes, and that our goal in transport should be to mitigate climate impacts. However, this is not a very widely held view.

The views are usually more along the lines of: “Yes, climate is a big problem and we need to solve it, but traffic congestion in our communities is so bad that it's a pressing issue, so we just need to do this project now” . People talk about trucking issues, about community members attending council meetings, and about the difficulty of getting their kids to school — in many California communities, the main mode of travel is highways. So for them, while climate change mitigation is a very important goal, it's not the issue today. That's tomorrow's problem, what they have to do today is relieve congestion, and the solution is to expand the highways.

There is also a very technocratic debate about induced travel – although some would say it is a philosophical debate under the guise of a technical debate. It has some similarities to climate denialism, with varying degrees of denial. You won’t hear many people say outright: “I don’t believe in induced travel,” even though that does sometimes happen. Others said they believed induced travel was a common concept, but they didn't think it was happening in their own communities. Or they think, “My project is special and won’t cause travel.”

YCC: If I understand correctly, California has climate-focused policies in place to prevent highway expansions that would cause people to travel, but these expansions happen frequently anyway. Is this accurate?

plum: Yes. You do hear some people saying, essentially, “Yes, California has greenhouse gas goals, but there are many goals, and the goals are not ranked or prioritized. So why should transportation focus on climate rather than economic development? So California There are policies for this, but it does not reign supreme in the minds of many actors.

If you engage in one of my hobbies, which is listening to public meetings, you'll hear this a lot. People will say, “This project is inconsistent with the goal of reducing carbon emissions, but this is a very important freight corridor.” Most appointed and elected officials seem unwilling to do anything that might be seen as harming freight and economic activity. As one person said to me, “Cargo transportation projects are like motherfuckers and apple pie—everyone loves them except the communities that have to live near them.”

YCC: I thought trucking and “freight hauling” were essentially semi-trucks?

plum: Yes. All of California’s transportation and climate policies even have special provisions for freight. Although trucks cause significant air pollution, health risks and significant carbon emissions, it only involves passenger transport.

Another issue that cannot be ignored when considering highway expansion in California and throughout the United States is the larger political economy built around large-scale infrastructure projects. There are many people who produce concrete and aggregate for highways or work for construction companies that build highways. In California, where Democrats hold a solid majority in the Legislature, labor and unions are very powerful players. So while there are policies to reduce emissions, there are also many material benefits to the construction of large transportation capital projects, and these groups get the attention of elected officials. That $30 billion in transportation funding could bring in a lot of money.

YCC: One of the reasons induced travel is such an interesting concept to me is that it basically means you can't have a transportation system based solely on cars that people are actually happy with, because you'd never be able to build your own transportation system. The way traffic jams – they're basically built into it.

plum: Yes, that’s what California’s climate and transportation policies are trying to accomplish: essentially achieving more intermodal accessibility by coordinating land use and transportation planning to reduce dependence on cars. The idea is to give people more options for getting around such as public transport, walking and cycling.

It’s a wonderful vision, but how it works in practice is the real key. As many people from the transportation policy world told me, the most salient political issue for many elected officials, especially at the local level, is traffic congestion. Local people hold a lot of power; policy in transportation is very decentralized. Crowding is a very prominent issue for local politicians. They need to show they're trying to do something to help it, even if it doesn't solve the problem in the long run: they just need to be re-elected.

Local politicians rarely pursue upstream solutions, such as building new housing in urban areas, which would help people walk and cycle to work instead of taking the highway. Housing development is a slow process and is not openly controlled in the United States. Transport, on the other hand, is publicly funded. As a result, local elected officials use transportation as an area in their efforts to serve their constituents.

Expanding the expressway also seems to be a no-brainer. Improving housing options and public transport are more effective ways to help people avoid crowding, but this requires efforts to get them to imagine a different future. And with highway expansion, you just tell them, “I'm going to help you with the highway all the time.” So it feels very obvious and direct.

Most elected officials are not keen on these things, right? They came into office without a lecture on induced travel.

But you'll never solve congestion this way; we've proven it time and time again. Everyone likes to think of Los Angeles as a car town, and this is a classic example of, “Look, they build as many freeways as they can, but it's still crowded.”