DZBLs and Bicycle Facility Advocacy

For those who might not be aware of the problems created when a cyclist rides too closely to parked cars; this video is a powerful graphic illustration of what happens when a cyclist collides with an opened door of a parked car.

Not only are the injuries from striking the door potentially serious, the physics of the situation immutably means that the cyclist ends up being thrown into traffic. This last part is something that I had not been aware of…. so please watch the video….

Experienced cyclists know to avoid this danger by simply riding further to the left, unfortunately the timid or untrained gravitate too far to the right because they misunderstand the sources of danger.


So, then there’s a “door zone” near any parked vehicle which can lead to a collision, otherwise referred to as a “dooring”. The risk is heightened when a bike lake is placed too-near parking, thus the term DZBL, a Door Zone Bike Lane. Cyclists, quite naturally, expect to be able to safely ride down the middle of any bike lane.

Dan Gutierrez has an extensive set of photos and slides showing dimensions and examples in facebook photo album: Door Zone Bike Lane and Sharrow Clearance .(which apparently now must be logged into facebook to view, even though it’s public — damn facebook).

There are loads of other references on the internet, just search for DZBL or ‘dooring’ see e.g. , John Allen on dooring  .

Bicycle Facility Advocates versus Bicyclist Advocacy

The photo shows a deep yearning by some to have bicycle facilities even where there is not enough space to allow for a properly engineered one. The theory being that a “small” bike lane must be better than none at all — a half-a-loaf idea. What is actually shown is two narrow travel lanes of something less than 11′ width, and a two foot shoulder. The stripe is an edge line, and the “bike route” sign only serves to further reinforce the idea in the minds of the uninformed that this is a bike lane. Somewhat ironically, the median is very oversized and the extra 3 feet or so (1.5 feet in two directions) could have easily accommodated actual bike lanes within the existing right-of-way. In other words some pin-head City of Phoenix “planner” thought this was a great idea; to have a gigantic median and “skinny” bike lanes, all nice and (bike)friendly-like, right? (This is Chandler Blvd, west of 24th St, Phoenix. The median is approx 30′ wide, see this article for more particulars)

To switch back to DZBLs, the group put out a video extolling the virtues of a road-diet they successfully advocated for; a traffic lane was removed and a bike lane was added. So far so good, but in the screen-grab to the left you can clearly see that this is a DZBL. Now, I’m all for road diets; but placing a bike lane right next to parking indicates a world-view that bike facilities must come first, ahead of, say, the safety of its users. And I don’t mean to pick on bike-pgh, just to point out that that viewpoint seems to be rampant within the ranks of “bicycle advocates”.

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