Designing Intersections Your Grandma Can to Cross

There is a huge push for protected bike lanes in the U.S. that separate bike and car traffic. While this is a great step, neglecting to continue this protection and separation through intersections defeats the whole purpose. Most crashes between cars and bikes occur at intersections–it only makes sense to enhance safety measures here, and not abandon them completely. Still, this is the case in many places in the U.S. where the bike lane is dropped right before going into an intersection–it really doesn’t make any sense. A low-stress cycling network is only as good as its weakest link.

The Dutch Way

In 2011, Mark Wagenbuur posted a video on his  blog, Bicycle Dutch, reviews the last design guidelines for intersections from the National Association of City Transportation Officials (NACTO), a North American transportation association. He disagreed with the recommended best practices including the two-stage left turn (with queuing boxes) and the “bike lane/turn lane” or “bicycle pocket” approach that allows a through bike lane and a pocket right turn lane (creates a mixing zone between cars and bikes).

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Screenshot from “Junction design the Dutch – cycle-friendly – way” depicting the “mixing zone” for cars and bikes on a standard U.S. roadway. Source: Bicycle Dutch, 2011

The Dutch no longer commonly use these practices, but rather opt for safer designs that keep bike and car traffic separated. In follow-up blog post from Wagenbuur in 2014, he discusses designs for a common Dutch protected intersection, roundabouts, and underpasses/overpasses. He reviews a few designs from cities that have not quite interpreted the Dutch protected intersection correctly. He also mentions Nick Falbo’s protected intersection video, which he suggests is a good interpretation of the Dutch model.

Designing a Protected Intersection

When approaching Dutch protected intersections, the bike lane or cycle track is kept to right of motorized traffic lanes. At the intersection, the Dutch use a few key design prinicples to ensure the safey, comfort, and convenience for bicyclists:

  1. Create good flowing cycle tracks without tight turns that allow cyclists to ride at faster speeds.
  2. Corner islands protecting cyclists have the same radius as the existing curbs and are opened up to allow for through-bike traffic.

 

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Curbs and corner islands create a permeable barrier for bikes at every corner of the intersection. Adding color to the cycle tracks and dashed lines at crossings provides further clarity for road users. Source: Bicycle Dutch, 2011

3. The corner islands allow for an advanced stop line for bicyclists to avoid right-hook conflicts. Cars meet bikes at the crossing at a 90 degree angle, which allows for better eye contact.

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A right-turning car and a cyclist meeting at a 90 degree angle. Source: Nick Falbo, 2011

4. Shifting back the stop line for cars provides space for a better, shorter pedestrian crossing.

Zebra crossing

Shifting back the stop line for cars gives room for a shorter pedestrian crossing.

5. Often bikes and pedestrians are given priority at crossings. In the Netherlands, this is indicated by sharks teeth yield markings for cars. By giving cyclists priority at intersections, they are able to quickly and safely clear the intersection.

Other notable intersection designs that the Dutch commonly use include roundabouts and bicycle underpasses or overpasses. Roundabouts with cycle tracks that give priority to cyclists are considered much safer than traditional four-way intersections and are preferable to use when space allows. They can be employed in both urban and rural settings. They also allow for better flow and capacity than traditional intersections. Bicycle underpasses and overpasses are used when bicycle routes cross busy arterials or highways where it is best to completely separate the two types of traffic.

Moving Forward in the U.S.

The protected intersection an important design that needs to be better implemented in the U.S. Currently, only six cities in North America have protected intersections including Chicago, Austin, Vancouver B.C., Davis, Montreal, and Salt Lake City. It does not take up anymore space than a traditional intersection design and can be used for signalized and even unsignalized intersections depending on traffic volumes.

While roundabouts and bicycle underpasses/overpasses are also great designs for crossings, they may require more convincing and/or funding in the U.S. to make them feasible.

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