Science Friday
Hosted by Flora Lichtman and Ira Flatow
Decades of research shows that expanding highways, despite its promise to reduce congestion, actually increases travel times.
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States across the country spend billions on highway construction projects that don't relieve congestion. Now, some cities are rethinking the future.
I've only ever grown up in cities wrapped by highways. It's hard to imagine anything different. But like, a lot of cities are tearing down highways and building something else in their place.
It's Monday, November 11th, and you're listening to Science Friday.
I'm Sci-Fri producer Dee Peterschmidt. Have you ever been stuck in traffic and had the thought, if only this highway was a little wider so it could fit more cars? Well, you aren't alone. In 2022, federal, state, and local governments in the US spent $127 billion on highway construction. Their transportation departments say expanding highways is necessary to ease traffic and to encourage economic development. But decades of research shows the opposite effects when highways are expanded, that travel times actually increase when more lanes are added, not to mention the extra pollution that comes along with them. So how does this happen? And why do we keep expanding highways even though the research says it doesn't work? Here's Ira Flora with more.
Here to explain the science behind highway widening and how some states are actually rethinking their approach to traffic is Megan Kimball. She's a journalist and author of the book City Limits: Infrastructure Inequality and the Future of America's Highways. She's based in Austin, Texas. Welcome to Science Friday.
Thank you for having me.
Lots of highways in Austin, right?
Lots of highways. I'm one mile from I-35 right now.
Well, let's get to the point. You know, it does seem logical that if you want less congestion, you just widen the road. But that, the data shows that widening actually makes traffic worse, right?
Yeah, it's certainly intuitive. Like you said, if you're sitting on a highway in traffic, you think, you know, one more lane will get this traffic flowing more quickly. But yeah, it's actually been well understood for decades that when you add capacity to a highway in the form of new lanes, more cars will rush to fill up that capacity. So that was first articulated in 1962, so just a few years after the Interstate Highway Program began. An economist looked at all these new highways that were being built in American cities and saw that as, you know, lanes were added, as capacity was added, the total traffic was increasing. And this is because travel is a good like any other. It follows the rules of supply and demand. So when you increase supply, demand also increases. So people change their behavior. They maybe move farther from their job and
they take on a longer commute because they think they can get there quicker, or they take more discretionary trips. So they go to the grocery store three times instead of one time.
Right.
And overall, traffic volumes increase. So the sort of stated goal of fixing traffic congestion by adding lanes fails in project after project, city after city, when highway departments widen highways, travel times actually increase.
Right. But you know, states are also talking about climate goals, you know, we're going to reduce smog and pollution and greenhouse gases, but more cars are just the opposite, right? When you widen the highways, you're having an environmental impact.
Yeah, you're measurably increasing greenhouse gas emissions. A stat I found when I was reporting my book that absolutely floored me is that on-road emissions in Texas, so you know, the emissions generated by our cars and trucks, account for half a percentage of total worldwide carbon dioxide emissions.
Hmm.
So like, the highway expansions that I profile in my book, like, whether those go forward will have a measurable impact on like, global climate emissions. Like, every one of these highway expansions contributes to that number. There's been a lot of research lately that shows that, you know, highway widens are the number one lever for states to pull to either reduce or increase their greenhouse gas emissions. So you have a lot of governors saying, you know, we are committing to ambitious climate goals, and then their state DOT are funding highway widens.
Right. Well, can you point to any benefits of highway expansion?
I mean, you certainly can allow more cars on the highway, right? So you do, in fact, increase the total number of people that can drive on a road, right? Like, if you expand something from two to four lanes, more cars spend on that road. But I think the, like, question is, do we want to encourage driving? Like, do we want our public policy decisions and public funding to be spent in such a way that it encourages people to drive? So, you know, the highways enabled the growth of the suburbs. They allowed people to buy more affordable housing out in the fringes of cities because they promised, you know, speedy access back to job centers and schools. But like, what is often not factored in is that has come an enormous cost. So there is certainly a benefit in the sense of, like, it has allowed kind of cheaper
housing, but when you combine housing and transportation, when you factor in the cost of gas and car insurance and the externalities of greenhouse gas emissions, it actually is not so cheap anymore.
Yeah, and these highways are also pretty expensive to maintain, right?
They're expensive to build and they're expensive to maintain. Yeah, I mean, this, I started reporting this book because I learned that the state of Texas had allocated $60 billion, that's billion with a B, to expand highways in five major Texas cities. And it's an extraordinary amount of money to be spent, as we started talking about not actually solving the problem we set out to solve.
Yeah, and you point out in the early days of Thoughts About Highway Expansion that when it was studied, there were even recommendations that the money would better be spent on public transportation.
Yeah, this is one of my favorite stories that I encountered while reporting my book. So when Eisenhower sold Congress on the interstate highway program, he promised it is one of national defense, so it was going to connect the country in the case of atomic, an atomic bomb or nuclear attack, and also build economic prosperity, that we were going to enable trade across this vast nation of ours. So it very much was a program to connect the country. And what the interstate highway program did is it enabled $25 billion, the largest public works project ever attempted in American history, and the federal government would pay 90% of the cost of construction of these interstate highways. And so the money flowed directly to state departments of transportation, which were called Highway departments with essentially no oversight by the federal government. And so what states started doing because they had, you know, lots of money flowing into their coffers
and people were buying cars in record numbers is they started building massive highways in the middle of cities. And so they started trying to use that federal money to solve this sort of local problem of urban congestion.
Yeah, that's not what Eisenhower wanted it for, right?
That's, yeah, that's not what Eisenhower intended. And we know that because he, he appointed this guy John S. Bragdon as, as a special assistant to the president to oversee the implementation of the interstate highway program. And Bragdon looked into the matter a few years after the program passed and found that it was running significantly over budget. And it was running over budget because states were using this federal money to build urban highways, which are much more expensive to build than rural ones. And so he asked Congress, like, was that your intent of the program was to solve this problem of local congestion? And he presents his findings to Eisenhower in the spring of 1960. And it's like a really remarkable presentation. I found the actual, like, note cards in the Eisenhower Presidential Library of the text that Bragdon presented to Eisenhower.
And in it, he says, you know, practically all the experts on the traffic problem of cities agree that the way to solve urban congestion, rush hour congestion, is through transit. You know, people take up less space than cars and urban transit is the solution. But what cities are doing currently is they are using this federal money through the interstate highway program to rip out existing transit systems and build massive highways in their place. And Eisenhower responds and he agrees. He says, those who had implemented the project, the program in this way, had done so against his wishes. You know, he had never intended these massive highways to be built through the center of cities.
Right. And, and when they started ripping out places to build these highways, the demographics were, were not quite equal for black and white, were they?
No, I mean, this coincided with the era of urban renewal in which city planners, you know, were looking at quote unquote blighted neighborhoods, predominantly occupied by Black and Hispanic families, neighborhoods that had been blighted by the same federal government a couple of decades earlier through the practice of redlining, and they saw an opportunity to clear those neighborhoods. So it's very clear in the historic record that planners intentionally routed interstate highways through Black and Hispanic neighborhoods and displaced half a million people from their homes along the way. And so it very much had a disproportionate impact on those neighborhoods. And that impact is still being felt today. You know, people who live next to highways suffer higher rates of respiratory diseases, and those are still mostly communities of color.
Right. And as you say, specifically in Texas, and I didn't know they have the largest highway in the country, 26 Lane Katy Freeway in Houston?
Yeah, the Katy Freeway is like the textbook example of induced demand. It's 26 lanes, including frontage roads. It is this massive highway, and TechStop expanded it about a decade ago, and within five years, rush hour travel times got worse. And people in Houston like drive on that highway. They understand that. Like, I was really struck reporting my book. I went door to door with, you know, a lot of activists who were trying to stop a different highway expansion. And people in Houston understand the phenomenon of induced demand. You know, they don't necessarily call it that, but when you live in a place that is covered by highways and you still sit in crushing traffic, like, you might wonder, why do we keep doing this?
Yeah. And let's talk about that. You wrote about the efforts of anti-highway expansion groups in Texas, and there were some successes.
Yeah, so a group in Houston called Stop TechStop I-45 started going door to door to stop this massive highway expansion. It's called, locals call it the I-45 expansion, but it actually impacts three interstate highways and will rebuild and reroute the entire downtown loop in Houston, along the way displacing 1,200 people from their homes, consuming 450 acres of land. And it's currently an $11 billion project. And a lot of the people who are in the footprint of the expansion didn't know that their homes would be taken. They didn't know they had any way to fight back. You know, the authority of eminent domain is absolute. TechStop can say, hey, we want your home, and then all they can do is negotiate on the price. But this group of just volunteers started going door to door in those neighborhoods impacted by the expansion, saying, hey, do you want this? Hey, do you know that you
can say, you know, you can voice your opposition? TechSouth's own analysis found that the people impacted by this highway expansion were predominantly minority. And so a few of those people filed civil rights complaints, saying this project violates Title VI of the Civil Rights Act because it disproportionately impacts Black and Hispanic people. And as a result, the federal government actually, under Pete Buttigieg, intervened to pause that project. So they said, hey, TechSouth, we need you to stop work on this project while we investigate these serious civil rights complaints. And those were filed by normal people, you know, people who I spoke with, who live in the footprint of the expansion and said, hey, this isn't fair. This is unjust.
After the break, why some cities are deciding to take down their highways and what's being built in their place.
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And this is happening in cities across the country, people fighting back and cities, some of them actually taking down their highways.
Yeah, I mean, there's this kind of new resurgence of freeway revolts, which people might remember in the 1960s, there was this massive resistance to highway construction. You know, as these highways came into American cities, tens of thousands of people poured into the streets and said, we don't want this. And they stopped highways from being built in Baltimore and Portland and Seattle. I mean, across the country, there were really successful examples of freeway revolts. And there is this sort of burgeoning movement today of kind of this new generation of freeway fighters, many of whom are galvanized by climate, who see the climate impacts of these highway expansions. And they're really trying to stop highway expansion across the country.
And you've mentioned in your book that there are cities that are actually taking down their highways. What cities are those?
Yeah, about 18 cities across North America have either taken down highways or committed to doing so. So one of the ones I profiled in the book is the city of Rochester, New York, which had this interloop highway circling its downtown, you know, this kind of moat, this sunken highway that really cut off downtown from the surrounding neighborhoods. And, you know, that highway enabled people to actually leave the central business district. And so the downtown had been kind of hollowed out. And starting about two decades ago, city leaders started talking about, what if we just took that highway away? You know, what if we removed it? And in 2017, the city got a grant from the Obama administration and they filled in the interloop highway, you know, they brought it up to grade and they made a two-lane city street in its place, built this really wide, beautiful sidewalk
and bike lane. So there are now apartments built on land that used to be a highway. Most of those apartments are rented to families earning below the median income, you know, three or four-story buildings. And it's pretty remarkable to go walk. You can see part of the the interloop highway remains. The city of Rochester is in the process of actually filling in the rest of it now. But you can go today and see this like sunken highway and then walk two blocks and see like a neighborhood, a city. It's populated. People are walking, they're riding their bikes. There's a brewery right there. And it's really remarkable to see like, we can reclaim that space. Like, I think a lot of people, myself included, like, I've only ever grown up in cities wrapped by highways. It's very hard to imagine them gone. And it's hard to imagine anything different. But like, a lot of cities are tearing down
highways and building something else in their place. And that can happen over like five years. That can happen very quickly.
And Colorado is actually taking a different approach, right? What are they doing?
Yeah, so that really shows how this is a climate story. So Coloradans elected a governor, Jared Polis, who made climate a top priority of his administration. And the legislature passed a bill requiring all state agencies to make a plan to reduce greenhouse gas emissions by 90% by 2050. And so the Colorado DOT looked at its portfolio of projects, which included widening I-25 through the heart of Denver and said, hey, we can't actually widen this highway and meet our greenhouse gas targets. And so they took that widening off the books. They said, we're not going to do this and we're going to allocate that money to something else. And that something else is bus rapid transit. So basically, we're going to help build a more robust transit system in Denver so that people can ride the bus, which lowers greenhouse gas emissions and get people where they're going without a car.
And that is like a really remarkable example of climate policy dictating transportation funding.
Very interesting. You've been reporting on this issue for a long time. You've written the book, City Limits. What's your biggest takeaway on this topic after all of these years?
Yeah, I mean, I started reporting the book with like, kind of the same question that you have in this program, which is like, if widening highways doesn't work to fix traffic, why are we still spending billions of dollars to widen highways? And like, the answer I have come to after, you know, four years of reporting is that there is this persistent belief in the US that cars help create prosperity, that cars enable economic development and that like, without a car, our economy will collapse. And so many other countries disprove that. Lots of cities in the US disprove that. There's so many different ways to kind of tilt at that narrative, but that is like this persistent belief from politicians of both parties that cars create prosperity. And like, until we counter that, we're going to keep making the same mistakes.
Do you think that that might be changing? Are people thinking differently, starting to look at highways in their neighborhoods in a different way?
Yeah, absolutely. I mean, like I said, it's definitely becoming a climate fight. People are realizing that widening highways is only increasing our emissions. But I think it's also becoming a quality of life fight. You know, young people don't want to drive. They want to live in places that are walkable. They want to not spend the money on cars. You know, a car is often the largest share of a household's disposable income after housing.
And so people don't want to spend the money and they don't want to spend the time driving. So I think there is a real shift, particularly as like younger generations move into the housing market. They don't want to just live in the suburbs and drive everywhere they have to go.
Yeah, this is a fascinating book, Megan. As someone who loves to read about highways and traffic and stuff, you've done a wonderful job here explaining the whole thing to us, especially the history of it, which is fascinating itself. Thank you very much for taking time to be with us today.
Oh, thank you, Ira. Thanks for having me.
Megan Kimball, journalist and author of the book City Limits: Infrastructure Inequality and the Future of America's Highways. And you can read an excerpt from that book on our website, sciencefriday.com/highways. And speaking of highways and books, every month, members of our Sci-Fi Book Club read a fascinating science book. And next month's book is Crossings: How Road Ecology is Shaping the Future of Our Planet by Ben Goldfarb. It's an investigation of how our roads have transformed the planet and the innovations that can minimize their threat to wildlife. You can join our online community of book
lovers and science nerds and enter to win a free book. Just go to our website, sciencefriday.com/bookclub.
And that's the show for today. A lot of folks helped make it happen, including Emma Gomez. Annie Nero. George Harper. Santiago Flores. On tomorrow's episode, your doctor might be taking your blood pressure wrong. We'll find out what to do to get a good reading. I'm Sci-Fi Producer Dee Peterschmidt.
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