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Ask i am traffic: Shoulders as Bike Lanes

April 2, 2014/2 Comments/in Engineering/by Dan Gutierrez

Nick Kasoff in Ferguson, Missouri asks:

Our local highway and traffic department has striped a “bike lane” on the shoulder of a busy road. Aside from the fact that it is a bike lane, there are two big problems – the concrete aprons from all the driveways extend across the bike lane (but not into the general travel lane), and much of the bike lane is split between “road grade” pavement and “shoulder grade” pavement by a meandering line. Needless to say, such pavement conditions are very unsafe for a cyclist.

I brought this to the attention of the highways and traffic people, and this is how they responded:

“This Department considers the shoulder … suitable for a bike lane.”

I don’t use the bike lane anyway, but its existence makes motorists much more aggressive toward my presence in the traffic lane. So my question is this: Are there any standards at all for condition of the paved surface in a bike lane?

This crappy shoulder condition problem highlights the disconnect between how engineers and legislators define the roadway. The legislature typically defines the roadway as exclusive of the berm or shoulder, and defines bike lanes as that portion of the roadway set aside for the exclusive or semi-exclusive use of bicycles. The engineers routinely include the shoulder in the definition of roadway and than refer to the legal roadway as the “traveled way”.

This nomenclature disconnect sets up the problem Nick is facing, since the engineers consider a bike lane NOT part of the traveled way, but as a part of the engineering roadway via the shoulder, and since shoulder standards are NOT bike compatible, they can tell Nick to suck it up and live with it. Yet if they followed the legal definitions, the shoulder would NOT qualify as roadway space, and could not be converted into a bike lane without upgrading the space to legal roadway (what the engineers call “traveled way”) standards.

This slide, showing minimum edge bike lane widths from the classes I teach to professionals, shows the disconnect as it relates to shoulders and bike lanes. CVC = CA Vehicle Code, HDM = CA Highway Design Manual.’

5_1_Slide26

And a similar problem exists for door zone bike lanes:

5_1_Slide30

 

Dan Gutierrez
Dan Gutierrez

Dan Gutierrez is a physicist, satellite engineer, chess master and stair walker. He and Brian Desousa invented the Dual Chase video technique. They also authored the pioneering study of how motorist overtaking clearance relates to bicyclist lane position.

https://iamtraffic.org/wp-content/uploads/2014/04/13587320605_4b54e91e70_z.jpg 427 640 Dan Gutierrez https://iamtraffic.org/wp-content/uploads/2013/02/iat_fb_profile2-300x300.jpg Dan Gutierrez2014-04-02 21:07:482024-08-01 15:27:11Ask i am traffic: Shoulders as Bike Lanes

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Keri Caffrey on bicycle
Keri Caffrey

 

I am a technical illustrator and graphic designer with over 30 years as an urban bike commuter, recreational group rider and ride leader. I am convinced that the greatest challenges facing American bicycling are a lack of education and a destructive belief system about our public roads.

Through CyclingSavvy, Mighk Wilson and I created a toolset for bicyclists to enhance their preferred style of riding. Together, we can transform our traffic culture to recognize that roads are for all people, not just motorists.

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