Four photographs show different bike lane designs along roadways: paired images showing different bike lanes, judging which seemed safer: a lane with (clockwise, from left) a low metal bar barrier, intermittent flexible posts, a raised curb and a lane that is completely separate from the roadway.

Separated Bike Lanes: Filling the Gaps in Design Guidance

In recent years, many U.S. cities have been installing separated bicycle lanes (SBLs) as part of their nonmotorized transportation networks. SBLs are bicycle pathways that employ paint and a vertical element as a buffer to separate motor vehicle traffic from bicycle traffic. They reduce crash risk, increase safety and comfort, and encourage more people to use bicycles as transportation. 

While demand for SBLs in the U.S. has increased, research on the most effective designs and strategies has not kept up with need. Although several organizations have published useful design information and the Federal Highway Administration (FHWA) offers the Bikeway Selection Guide, there are substantial knowledge and design gaps in these available resources. 

“The results of this project provided substantial information that will help planners and designers to create the safest and most effective bicycle facilities in a wide range of urban contexts,” said Paul Oehme, public works director, City of Lakeville.

MnDOT and the Local Road Research Board (LRRB) wanted to create an SBL guide that would gather design elements of greatest overall interest to practicing engineers, as well as investigate design issues and other aspects of concern to engineers that were not adequately covered or were missing from existing guidance entirely. 

What Was Our Goal?

The project’s goal was to produce supplemental guidance addressing SBL design options, as well as to investigate and present context-related aspects and challenges associated with SBL designs in Minnesota. The overarching objective was to provide engineers and policymakers with the current SBL design guidance they needed to inform their decision-making regarding bicycle infrastructure installations and improvements. 

What Did We Do?

Topic areas selected as the design guide’s focus included:

  • Buffer design.
  • Mixing zone design (intersections, areas of bike/vehicle interaction).
  • Bus stops on SBLs.
  • Winter maintenance.
  • Summer maintenance.
  • Relative costs and benefits.

The research team first conducted a synthesis of available literature about SBL design, understanding that SBL and bikeway design overall are evolving areas with research in progress and industry guidelines actively advancing. Nevertheless, the team’s synthesis of available design guidance was extensive and served to identify knowledge gaps in need of further investigation. 

Then the team identified active stakeholders to provide representative perspectives, particularly addressing safety, comfort and connectivity—three guiding principles of SBL design. Researchers first interviewed professionals from local agencies operating SBLs, focusing on designs used and implementation and maintenance concerns. Additionally, Twin Cities transit drivers were asked about challenges SBLs present to bus drivers. Researchers also interviewed the leaders of four bicycle advocacy organizations for their perspectives on bicycle users’ experience. 

Paired photographs show bike lanes in winter along a roadway from the point of view of the gloved cyclist, looking forward over the handlebars. The upper image shows a bike lane with some snow and no other riders. The lower image shows a lane with a bare pavement path and another cyclist ahead.
Survey participants were shown paired images of different bike lanes and asked to select the lane that seemed safer. 

An online user survey completed by hundreds of Minnesota bicyclists examined bicyclists’ perceptions of the safety and comfort of different SBL designs, including intersection and bus stop strategies. Survey questions also investigated winter riding and winter lane maintenance—key areas of guidance shown to be missing in researchers’ review of current SBL design. 

What Was the Result?

The compendium of SBL design guidance gathered from this effort will be valuable into the future. The existing guidance emphasizes strongly the SBL as the highest quality bikeway facility available. In addition, researchers’ interviews and the survey generated valuable and actionable information about SBL designs and bicycle travelers. Interviews with planners and designers showed that design refinements were most needed for buffers, mixing zones and bus stops to increase bicycling safety, comfort and the likelihood that bicycling would be chosen for transportation.  

“Our research confirmed that the majority of potential cyclists prefer design options that maximize separation from vehicles. The implication is that designs that reduce risk by maximizing separation are also most likely to promote new demand: More cyclists lead to more new facilities,” said Greg Lindsey, professor, University of Minnesota Hubert H. Humphrey School of Public Affairs.

The user survey revealed that cyclists are not a homogeneous group. Some are confident and proficient in traffic, but many are interested but concerned users. Design considerations must cater to these riders whenever possible to foster greater demand. While designs that avoid traffic altogether are not feasible, designers should keep in mind always that people who cycle prefer to minimize interactions with traffic between origin and destination. 

The project showed that SBL design is a highly local, decidedly context-specific infrastructure problem. There is no one best SBL design. The need for separation is the guiding concept; all else is context—including intersections, bus stops, parking, alleys and driveways, snow removal and stormwater flow—as designers brainstorm, making trade-offs among constraints to reach variations approaching separate SBLs. In support of this need, researchers developed a set of four trade-off matrices to help designers manage complex contexts and create the safest bike facilities they can. 

What’s Next?

The project collected extensive data and provided new strategies for framing the SBL design problem. Design practitioners must keep in mind that enormous flexibility exists within the still evolving design guidance to create bicycle networks everywhere. 

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