Multimodal Safety Challenges Associated with Designing the Protected ‘Dutch’ Intersection

The protected intersection is a way of accommodating separated bikeways at intersections. It is modeled after Dutch intersection design and includes the following features:

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Corner refuge islands that put the stop bar for bicyclists ahead of the stop bar for vehicles

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Bicyclist crossings set back approximately one car length from the adjacent travel lane

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Two-stage bicyclist left-turns

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Free bicyclist right turns

Bicyclist Design Challenges
  • Waiting space – Ensuring the space provided for waiting bicyclists/pedestrians is sufficient.
  • Use of two-stage left-turn for bicyclists – This allows bicyclists to cross without crossing oncoming vehicles but research indicates that many bicyclists may not use this application
  • Bicyclist signal phasing – Without bicycle signals, do bicyclists operate with vehicles or pedestrians? Current guidelines in the United States are unclear regarding bicycle signal application.
  • Conflicts between bicyclists and pedestrians – Bicyclists must yield to pedestrians at crosswalks.
  • If bicycle signals are used, bicyclists may lose the option to operate in vehicle travel lanes.
  • Protected intersections should be part of a protected bicycling network.
Pedestrian Design Challenges
  • Waiting space – Ensuring the space provided for waiting bicyclists/pedestrians is sufficient.
  • Conflicts between bicyclists and pedestrians – Bicyclists must yield to pedestrians at crosswalks.
  • Crossings for people with vision impairments – Crosswalks may not align with sidewalks which can become difficult to navigate for people with vision impairments (part of designing according to ADA standards for accessible design).
Automobile Design Challenges
  • Conflict between right-turning vehicles and bicyclists – Bicycle lanes to the right of a right-turn lane are not allowed per the MUTCD (U.S. standards).
  • A small corner radius is more desirable for minimizing vehicle speed through turns, but may be in conflict with bus and truck access.
  • Driver expectations regarding bicyclist positioning and driver behavior – How far do drivers have to look over their shoulder to see bicyclists?
General Design Challenges
  • No two protected intersections are alike. It is important to consider specific conditions associated with each location, such as turning volume.
  • Some agencies are considering slowing the speeds of approaching bicyclists through the use of rumble strips if speeds are an issue.
  • Some agencies had to modify their crosswalk design for pedestrian crossings on the bicyclist approaches.
  • The protected intersection will likely have longer cycle lengths than adjacent intersections, which can present coordination challenges and potentially lead to compliance concerns.
  • Retrofitting protected intersections into compact spaces might result in smaller-than-preferred island sizes which can present a tripping hazard for pedestrians or the potential for a fixed object collision for bicyclists.

 

 

Check out the first United States protected intersection in Davis, CA

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