Wednesday, November 21, 2012


A new study on walkers and bicyclists at roundabouts by the Minnesota Department of Transportation received some attention this week on the roundabout listserv hosted by Kansas State University.

(The study summary and access address to the study itself can be found at:

One of the most interesting aspects of the study was the walker delay.  A comparable traffic signal delay to the two roundabouts the authors stated would be 30 seconds while at the two lane roundabout the delay was 9 seconds and at the single lane roundabout 2 seconds.  The one lane roundabout was described as being in a "residential" area with 83 percent of drivers yielding to walkers.  The two-lane roundabout was described as being in a "suburban" area and 45 percent of drivers yielded to walkers.

My comment on the listserv to the study sent today was:

Not sure there are surprises here. What we know about walker--and bicyclist safety for that matter with no walkers and one bicyclist  fatality at a partially roundaboutized Los Altimatos Circle--is that the US/Canada roundies with all their early variations from current practice appear to be hitting the mark set by France with a walker fatality every 15,000 or so roundabout years.

This record so far surpasses signed/traffic signal performance that little regard (Lost Altimatos, again, a good example) can be given to safety at most existing roundabouts, rather it is more important to get more on the ground and access the 30% or so extra reduction in walker crash rates which come in all roundabouts once a certain (unknown) density of roundies occurs.  Of course, again, no one in the world has taken the effort to identify the crash reduction by mode out at incremental distances to a quarter mile from the center of roundabouts, i.e., the point where the traffic calming effect ends. 

The basic rules of roundabout design continue to apply for walkers and bicyclists--the smaller the roundabout the lower the speeds, the safer for non-motorized users. Wallwork ramps at entry/exits [for bicyclists to exit/enter rather than continuing through on the circular roadway.]x
Regarding yielding rates which clearly make little difference in  roundabout safety--roundabouts are by definition safe for walkers and bicyclists versus alternatives--regardless of yielding rates, just look at the overall safety record. 

My view on those persons with severe visual handicap continues that current street designs for them except in two cases remain unsafe at any speed--roundabouts or no but certainly for signs and signals.  (Remember US fatality rates for walkers and bicyclists are a few hundred percent higher than in urban Germany and the Netherlands--see Jean Pucher study on this).  Those with severe visual handicap can only be provided access in two cases:  (1) shared space and (2) use of a combination of traffic calming techniques (usually with roundabouts) reducing vehicle speeds to about 10 mph and below.  Incidentally, James Kunstler pointed to only three street malls in the U.S.--Burlington, VT Church Street Marketplace (where I am right now), Pearl Street Mall in Boulder and Santa Monica.  One of the first, Sparks Street in Ottawa still struggles, in my view because the lack of sufficient nearby parking and residential housing.

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