Laura Bliss is CityLab’s West Coast bureau chief. She also writes MapLab, a biweekly newsletter about maps (subscribe here). Her work has appeared in The New York Times, The Atlantic, Sierra, GOOD, Los Angeles, and elsewhere, including in the book The Future of Transportation.
So long as cars are among us, road pricing, ramp meters, and diamond-shaped intersections can mitigate horrendous commutes, a new video explains.
In 2004, the American Highway Users Alliance dubbed the Katy Freeway in Houston, Texas, the second-most congested freeway in America, squandering 25 million hours of commuters’ lives every year.
Texas’ solution? Go big. Today, the freeway spans a whopping 23 lanes, and claims the title to the widest highway in the world. The AHUA applauded the “fixed” bottleneck in 2015.
Only problem: traffic’s gotten worse. It’s the principal of induced demand: adding lanes almost always adds traffic. If widening highways can’t solve Houston’s commuter woes, what can? A new film from the video-explainer extraordinaire Wendover Productions has five ideas—and one grave warning.
- Ramp meters
Traffic slows exponentially—a small addition of cars can lead to a lot more congestion. But it also means removing a small amount of cars from the road can reduce congestion considerably. Ramp meters do allow one or two cars to enter a highway at a steady rate, keeping traffic speeds flowing at relatively efficient speed. They work: In 2001, Minnesota’s DOT switched off ramp meters to test their effectiveness. They found travel times slowed by 22 percent. “The ramp metering system produces an annual reduction of 2.6 million hours of unexpected delay,” a state report concluded.
- Road pricing
Roads are among the most valuable assets in a city’s portfolio, but few cities price them that way. That’s too bad, since charging drivers to enter certain areas, at certain times, is the single-most effective congestion mitigation strategy cities have at their disclosure. Stockholm decreased travel times by about 40 percent in 2006 by charging drivers just a couple of bucks to enter its city center—London, Singapore, and Copenhagen have seen similar changes with their congestion pricing schemes.
Solving traffic isn’t just about congestion—it’s also about safety. Replacing stop signs or signals with the circular anti-intersections can reduce serious crashes by up to 75 percent—and fatal collisions by up to 90 percent. (There is evidence that roundabouts increase less-serious crashes.) By slowing drivers down, eliminating left turns, and allowing traffic to flow uniformly, roundabouts are a engineering intervention to beat.
- All hail the shared street
Making cars play a little bit of chicken isn’t the worst thing. Stripping intersections of lanes, stop signs, signals, cones and crosswalks might sound like a death wish—but it actually forces everyone sharing the road to pay closer attention. That pays off: woonerfs, as the Dutch fondly dub such multi-modal walking, biking, and driving zones, can reduce crashes by about half.
- Rethink the traditional highway interchange
Highways aren’t going extinct anytime soon, so we may as well make them safer while they’re still here—namely, by reducing crash-prone conflict points at onramps. Diverging diamond interchanges (which have their own fan site!) guide both directions of traffic to cross to the opposite sides before they enter the highway, so that cars never have to make risky left turns. The U.S. DOT is a fan. About 90 of these crash-reducing interchanges exist in the U.S. now, with more on the way.
Traffic will never be “solved” until all cars are removed from the road. Indeed, to the five ideas listed here, we’d add funding and expanding transit options, supporting biking and walking infrastructure, and removing cars entirely from the densest urban areas.
But so long as cars are among us, there are ways to mitigate rush-hour headaches, and eliminate needless crashes, if transportation officials discard the old highway engineering manual in favor of solutions like these. “Until cities at least experiment with solutions,” the video’s narrator states, “we’re all condemned to traffic, forever.”