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Separated Bike Lanes, Automated Vehicles, and the MUTCD

In my last blog, I wrote about the need to reframe and rewrite the Manual on Uniform Traffic Control Devices because right now, the MUTCD is framed around motor vehicles. Today’s blog is an example of the inherent disconnect between the MUTCD and the many ways people use our roads.

Read our previous blogs on the MUTCD:




Since the last update to the MUTCD in 2009 one of the biggest developments in engineering for better bicycling has been the rise of the separated bike lane. 

Now, for the first time, the proposed 2021 MUTCD includes separated bike lanes explicitly in Section 9E.07 and in discussions throughout Chapter 9. This is a great advancement from previous editions and should help continue the proliferation of safe and separated bike lanes that previous design guides from NACTO, FHWA, and others had to assure were compliant with the MUTCD guidelines.

Unfortunately, the MUTCD stops short of providing the sort of guidance on when separated bike lanes are appropriate, found in documents like NACTO’s All Ages and Abilities Guide or FHWA’s Bikeway Selection Guide. This type of guidance, based on the speed and volume of motor vehicle traffic that poses a danger to people biking, is the type of “design guidance” that is separate from the “traffic marking” guidance found in the MUTCD.

However, the MUTCD is happy to provide guidance on the value of separated bike lanes when the context is not the safety of people who bike, but instead what is best to “accommodate machine vision used to support the automation of vehicles.” In the context of what is better for machine vision systems, like those that might be used in AVs, the MUTCD says, “bicycle facilities should be segregated from other vehicle traffic using physical barriers where practicable” which is both broader than guidance based on speed and volume and unsupported by cited research, unlike the FHWA’s own Bikeway Selection Guide. 

The willingness to embrace separated bike lanes due to the perceived needs of machine vision systems in motor vehicles and the unwillingness to embrace separated bike lanes due to research showing their safety advantages for people biking, walking, and driving is all too typical of the MUTCD. It is also precisely the type of motor vehicle-first approach to infrastructure development that has long created strife in the bicycling community due to an implied threat that people may – for their own safety – be banned from roads due to the dangers of interacting with motor vehicles.

Since the creation of the MUTCD and its forebearers in the 1920s began the project to make roadways places for motor vehicles, there have been disagreements among people who bike about how to adapt. The vehicular cycling movement reacted to bicycle bans by rejecting separated facilities that might legitimize those bans or require the use of separated facilities where they exist. In the MUTCD’s proposed guidance for automated vehicles, it repeats this process and threat, implying that roadways shared by bicycles and automated vehicles may be impracticable. The MUTCD’s identified need is the safe deployment of automated vehicles, not the safety of all people, and its project is technological advancement, which separated bike lanes might serve.

Resolving the fear of the bicycling community that they will be restricted access to roadways goes beyond the scope of the MUTCD, as does ensuring that automated vehicles are safe enough that they can be deployed without meaningfully restricting the mobility of people who bike, walk, and use mobility devices. However, the MUTCD is making its preference known and that preference is automated vehicles. 

The League of American Bicyclists believes that safe and connected bicycle infrastructure is a critical element to encouraging and enabling more people to bike more often. And when more people can safely and easily choose to bike, life is better for everyone. 

Separated bike lanes should absolutely be promoted in documents like the MUTCD and the safety, comfort, and convenience of people biking should be the reasons for doing so. People who prefer to ride in roadways (or who must because of lack of bike facilities and infrastructure), whether because they are faster, riding in groups, or otherwise should have the right and ability to do so, and the MUTCD should support those choices through appropriate markings and signage.

It is troubling that the MUTCD is not providing guidance recommending separated bike lanes based on safety, but instead based on enabling automated vehicle deployment. As we reshape our built environment, the reasons why we are doing so matters. Is it to help people thrive through safe and accessible ways to get around? Or is it to maintain a status quo where motor vehicle movement is prioritized? The reason provided by the MUTCD does not speak to a future where the mobility of people biking, walking, and using mobility aids means as much to the MUTCD as the continued reign of motor vehicles over our nation’s roadways.