Lobbyist Holds Up Spectacular Example of the Futility of Widening Highways

Crossposted from City Observatory

Here’s a highway success story, as told by the folks who build highways.

Several years ago, the Katy Freeway in Houston was a major traffic bottleneck. It was so bad that in 2004 the American Highway Users Alliance (AHUA) called one of its interchanges the second worst bottleneck in the nation wasting 25 million hours a year of commuter time. (The Katy Freeway, Interstate 10, connects downtown Houston to the city’s growing Eastern suburbs almost 30 miles to the east).

Obviously, when a highway is too congested, you need to add capacity: make it wider! Add more lanes! So the state of Texas pumped more than $2.8 billion into widening the Katy; by the end, it had 23 lanes, good enough for widest freeway in the world.

It was a triumph of traffic engineering. In a report entitled Unclogging America’s Arteries, released last month on the eve of congressional action to pump more money into the nearly bankrupt Highway Trust Fund, the AHUA highlighted the Katy widening as one of three major “success stories,” noting that the widening “addressed” the problem and, “as a result, [it was] not included in the rankings” of the nation’s worst traffic chokepoints.

There’s just one problem: congestion on the Katy has actually gotten worse since its expansion.

Sure, right after the project opened, travel times at rush hour declined, and the AHUA cites a three-year old article in the Houston Chronicle as evidence that the $2.8 billion investment paid off. But it hasn’t been 2012 for a while, so we were curious about what had happened since then. Why didn’t the AHUA find more recent data?

Well, because it turns out that more recent data turns their “success story” on its head.

We extracted these data from Transtar (Houston’s official traffic tracking data source) for two segments of the Katy Freeway for the years 2011 through 2014.  They show that the morning commute has increased by 25 minutes (or 30 percent) and the afternoon commute has increased by 23 minutes (or 55 percent).

Growing congestion and ever longer travel times are not something that the American Highway Users Alliance could have missed if they had traveled to Houston, read the local media, or even just “Googled” a typical commute trip. According to stories reported in the Houston media, travel times on the Katy have increased by 10 to 20 minutes minutes in just two years. In a February 2014 story headlined “Houston Commute Times Quickly Increasing,Click2Houstonreported that travel times on the 29-mile commute from suburban Pin Oak to downtown Houston on the Katy Freeway had increased by 13 minutes in the morning rush hour and 19 minutes in the evening rush over just two years. Google Maps says the trip, which takes about half an hour in free-flowing traffic, can take up to an hour and 50 minutes at the peak hour. And at Houston Tomorrow, a local quality-of-life institute, researchers found that between 2011 and 2014, driving times from Houston to Pin Oak on the Katy increased by 23 minutes.

Even Tim Lomax, one of the authors of the congestion-alarmist Urban Mobility Report, has admitted the Katy expansion didn’t work:

“I’m surprised at how rapid the increase has been,” said Tim Lomax, a traffic congestion expert at the Texas A&M Transportation Institute. “Naturally, when you see increases like that, you’re going to have people make different decisions.”

Maybe commuters will be forced to make different decisions. But for the boosters at the AHUA, their prescription is still exactly the same: build more roads.

The traffic surge on the Katy Freeway may come as a surprise to highway boosters like Lomax and the American Highway Users Alliance, but will not be the least bit surprising to anyone familiar with the history of highway capacity expansion projects. It’s yet another classic example of the problem of induced demand: adding more freeway capacity in urban areas just generates additional driving, longer trips and more sprawl; and new lanes are jammed to capacity almost as soon as they’re open. Induced demand is now so well-established in the literature that economists Gilles Duranton and Matthew Turner call it “The Fundamental Law of Road Congestion.”

Claiming that the Katy Freeway widening has resolved one of the nation’s major traffic bottlenecks is more than just serious chutzpah, it shows that the nation’s highway lobby either doesn’t know, or simply doesn’t care what “success” looks like when it comes to cities and transportation.

14 thoughts on Lobbyist Holds Up Spectacular Example of the Futility of Widening Highways

  1. The chart only shows travel times. Does the study take into account the fact that the suburbs are expanding and therefore resulting in greater distances?

  2. Chart claims to be between two specific points, so this hasn’t changed. And, really, have the burbs grown 50% farther away in 3 years?

  3. Part of the idea behind induced demand is that bigger freeways are precisely the reason for suburbs expanding.

  4. To be fair, the Katy Freeway added managed lanes (i.e. HOT lanes) as part of the widening. If you are going to add lanes, managed lanes are going to be the best way to go. I bet you the managed lanes are still carrying drivers at 60 mph+ average speeds, but they have to pay for the privilege.

  5. But those alternatives are the only cost-effective solution that relieves congestion and improves productivity at the margin, they shouldn’t have to be justified and limited by widenings.

  6. OK. Here’s what I’ve learned by studying road widenings:
    — going from a one-lane road to a two-lane road (one lane each way) adds a lot of capacity.
    — going from a two-lane road to a two-lane road *plus pocket turn lanes* adds a lot of capacity.
    — on a road with intersections, going from one lane in each direction to multiple lanes in each direction is essentially worthless.
    — going from a road with intersections to a freeway adds a lot of capacity.
    — going from a two-lane-each-way freeway to a three-lane-each-way freeway adds a *little* capacity
    — going from a three-lane-each-way freeway to more lanes is completely worthless.

  7. Yes, which is precisely what I was saying. Although the bottom of that list isn’t exactly true. If the freeway is separated into “local” and “express” portions that limit interactions to every couple miles, that can add a lot of capacity as well. This is also the same concept that HOT lanes operate under. But such schemes often require lots more space and especially in constrained conditions, may not be feasible.

  8. By managing lanes, you can actually milk more capacity because your freeway never falls into the congested state, as traffic moving at 20 mph does not maximize throughput at all. And building rail only makes sense if destinations are concentrated at one end of the other. The worst would be something like the 91 Freeway between Orange and Riverside Counties, where destinations are dispersed on either end – in that situation only managed lanes work to help reduce (not eliminate) congestion.

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