Housing Complex

Yes, Bike Lanes Can Reduce Car Capacity. But They Probably Don’t Worsen Traffic.

The nearly complete 1st Street NE cycletrack.

The nearly complete 1st Street NE cycletrack.

D.C.'s latest protected cycletrack, on 1st Street NE, is nearly finished. For bikers, this means a faster, safer way to travel through NoMa. For drivers, it's yet another reason to gripe about bike infrastructure slowing down car traffic. Or is it? FiveThirtyEight has a study today on this very issue. The takeaway is this: Yes, converting a car lane to a bike lane means less space for cars to drive, without substantially reducing the number of cars driving there. This would appear to mean slower traffic, except it usually doesn't. It all depends on the street's volume-to-capacity ratio—the number of cars driving there as a proportion of the number of cars that could drive there at maximum capacity. Traffic doesn't really start to slow down until this ratio passes 0.75. In Minneapolis, America's most bike-friendly city and the location of this study, turning a car lane into a bike lane did increase the volume-to-capacity ratio on all 10 roads examined, sometimes substantially. But it never pushed it past the 0.75 marker, meaning that congestion never got severe. In the worst cases, it probably got harder to change lanes, but in most cases, there wasn't a discernible impact on drivers' ability to move speedily. In other words, the impact on drivers was minimal. The impact on cyclists who use those routes, on the other hand, was likely substantial. Between 4 and 5 percent of Minneapolitans commute by bike. That's probably too small a number to make a noticeable dent in car traffic, but a big enough one to be worth catering to. It's also one that's likely to increase as bike infrastructure improves—protected cycletracks provide a sense of safety that encourages more people to bike—perhaps to levels that will start diminishing road congestion. In D.C., according to a recent Washington City Paper/Kojo Nnamdi Show poll, 4 percent of likely Democratic voters in the April 1 primary commute by bike. (That figure may actually underestimate the total, given that the poll was conducted by landline and surveyed likely voters—a demographic that skews older than many cyclists.) Again, that's probably not quite enough to produce a meaningful decrease in car traffic, but it could get there in the future with improvements to cycling infrastructure. And in the meantime, as long as the city's not putting bike lanes on its most congested roads, there's probably not much harm. I've put in a request to the District Department of Transportation for volume-to-capacity ratios on 1st Street and other cycletrack locations, and will update if I receive those.

Photo from @DDOTDC

This article originally said that the City Paper/Kojo Nnamdi Show poll queried D.C. residents. In fact, it was a poll of likely Democratic primary voters in D.C.


  • DC

    God that is a beautiful bike lane. Any chance that DDOT plans to build more like it?

  • West Ender

    "And in the meantime, as long as the city's not putting bike lanes on its most congested roads, there's probably not much harm."

    You mean like L Street?

  • Cyclist

    And putting protected cycle tracks on congested roads, may still be benefit cost positive.

  • Corky

    This story and study is knee deep in BS. Of course reducing a traffic lane will increase car congestion! What is it about bikers that they think everyone else is a complete idiot? And these lanes in DC ARE on congested roads!

  • Cyclist

    The bike lanes I use most often are those on Eye st SE/SW, at rush hour, and its seldom particularly congested. Ditto for bike lanes on 1st St SE, and I think on 4th St SW.

    You must be thinking of cycle tracks. Most bike lanes in DC are not cycle tracks.

    And as I said above, even when they are on congested roads, they can be worthwhile.

  • http://www.twitter.com/tonytgoodman Tony Goodman, ANC 6C06

    I just want to point out that this new First St NE cycletrack did NOT take away any other travel lanes. There were previously standard bike lanes on each side of the street. These were shifted to the East side and protected with a concrete curb to create the cycletrack.

    This is a very welcome addition to NoMa, and also serves as a portion of the Metropolitan Branch Trail.

  • 7r3y3r

    @West Ender - except the bike lane on L didn't take up a travel lane, it used a parking lane. So cars have the same room to move as they did before.

  • SSteve

    I love to bike and don't mind bike lanes too much. But you have to realize that they do slow down traffic when bikers don't follow the rules/lanes.

  • Nancy

    This is someone who hasn't tried driving up 15th street since the changes. What used to be a great way for me to direct a cab up to my place near the zoo has become a two lane hellish ride. Why a 3rd lane was turned into a "turn left only" lane I don't know, but it made the street a mess.

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  • http://www.eurotechtuningca.com/audi-repair/ Danish Richiee

    Yes I am agreed to your article . Bikes are most easiest way to reduce the traffic but its not possible for everyone to ride a bike. Of course cars are the reason for traffic congestion but we should look for alternatives to reduce the traffic. And one thing we should use fuel efficiency cars for a safe and healthy environment.