Bike Lanes Don’t Cause Traffic?

Data from major cities show construction of bike lanes is mutually beneficial

The fight for space on city streets wages on for road cyclists, bike commuters and drivers, but there may finally be data that could put the debate to rest.

Analytical website Five Thirty Eight has collected data from streets in both Minnesota and New York City to discern whether replacing a car lane with a bike lane is causing more traffic. Their conclusion: if the city chooses the right roads, the removal of a traffic lane and introduction of a bike lane will not cause an increase in traffic.

This is an important point: Bike lanes don’t cause a lot more congestion if you put them on the right streets. If you cut down the size of streets that are already near capacity, you’ll create severe congestion. But if you start with roads that are well under capacity, you’ll only increase the congestion a little bit. And it may not even be noticeable.

They started with data from Minnesota. Measuring the traffic at rush hour using data the city had collected before and the bike lanes were put in place, they found that the motor vehicle traffic had not changed. To explain the steady numbers, they used volume-to-capacity (V/C) ratios, which is basically a percentage for how full the road is.

As long as the V/C ratio is less than 75 percent, the flow of traffic is not an issue.

You can see the change in the Minnesota graph, but in reality the roads are still far from full capacity, which means traffic is not an issue.

They also took a look at a New York City street that switched a traffic lane to a bike lane. The chart showed similar results to those in Minnesota.

The Brooklyn street saw additional benefits after the bike lane was constructed. The average speed of cars on the road decreased, as did the rate of “injury-causing accidents.”

These results won’t be the same on every street; the key to keeping traffic down is careful placement.