Georges Jacquemart, P.E., AICP
|August 16, 2002|
I am writing to object to the wording in the first three paragraphs of section 1105.6 Roundabouts in the Draft Guidelines on Accessible Public Rights-of-Way and the recommendation to install pedestrian activated signals at roundabout approaches.
Anti Roundabout Bias
In the Draft Guidelines roundabouts are presented as a tool to increase vehicular capacity and reduce delays. By omitting to mention safety as a major benefit and a primary reason to build roundabouts, you misinform your audience. This comment also relates to Section 9.2.5 Roundabouts of FHWA’s publication “Designing Sidewalks and Trails for Access” Part 2. Also, other intersections such as yield-controlled intersections or right- turn slip lanes have similar features to those of roundabouts, when it comes to the ability of visually impaired pedestrians to detect certain traffic movements. Why not require that these have pedestrian activated signals as well? These documents are very important guides and include valuable information, but this bias has a negative impact on their credibility and legitimacy.
Implied Safety of Traffic Lights
By requiring that the roundabout approaches have pedestrian actuated signals you imply that there would be greater safety. There is no proof that signals improve pedestrian safety or safety for visually impaired pedestrians. In fact we have some statistics that suggest the contrary: The Philadelphia study showing a positive impact on pedestrian crashes after a large number of traffic signals were removed, and the fact that in New York City more pedestrians are killed while crossing legally at signalized intersections, than those that are killed jaywalking or those crossing at unsignalized intersections. The New York City statistic does not necessarily prove anything since we would have to calculate crash rates per pedestrian, however, it is a surprising statistic that shows that we have an exaggerated sense of security at traffic lights.
Safety versus Ease of Use
By now it is very clear that modern roundabouts have substantial safety benefits in the US, as well as in the rest of the world. The March 2000 study of the Insurance Institute for Highway Safety analyzed 24 modern roundabouts built in the US and concluded that total crashes were reduced by 39%, injury crashes were reduced by 76% and property- damage-only crashes were reduced by 34%. An October 2001 report by the Maryland State Highway Administration analyzed the crash statistics of eight roundabouts built by the State between April 1993 and December 1998 and concluded that the mean crash per million vehicles entering decreased by 69% for total crashes, by 89% for injury crashes and by 34% for property-damage-only crashes. These safety statistics are similar to those found in Europe and in Australia over the last 1 5 years. European studies also show significant safety benefits for pedestrians; and the limited statistics that we have in the US regarding pedestrian safety also point in that direction. As you know there are no data on crashes involving disabled users.
In my opinion it is wrong to put the proposed signalization rule for roundabout approaches in the context of safety (to provide safer crossing.. .allow safe passage... in the second paragraph). The concern being raised is the of crossing roundabout approaches by visually impaired pedestrians, based on the argument that visually impaired persons have difficulties differentiating between exiting and circulating traffic in a roundabout. The question is how we can help visually impaired pedestrians in making the decision when to cross at a roundabout, not how can we make it safer. I believe that the safety of visually impaired pedestrians at roundabout crossings depends more on the driver variables (lower speed of the vehicle, optimum visibility conditions, simplified conflicts) than on the visual abilities of the pedestrian.
The difference between perception of safety and actual safety is critical in the case of roundabouts since they do not lull users into an exaggerated sense of security as traffic lights do. At traffic lights users get very simple messages (walk, don’t walk, green, red), and unfortunately users associate this simplicity with safety. At roundabouts all users are asked to pay attention and often users perceive this as unsafe.
Overall Safety Impacts on the Disabled Population in the US
The number of disabled persons driving through roundabouts as drivers or passengers in vehicles is much higher than the number of visually impaired pedestrians crossing at roundabouts. As we build more roundabouts in the US the disabled population in the US will benefit from the substantial reduction of vehicular crashes in roundabouts. If the number of roundabouts built in the US is decreasing as the result of the signalization rule, the total population as well as the disabled population will be negatively affected. The proposed rule to install pedestrian activated signals at the roundabout approaches will have negative impacts on the operation of the roundabouts and will reduce the number of roundabouts that will be built. We have no experience with these types of installations.
To conclude, the proposed rule to install pedestrian actuated signals is not justified from a safety point of view and it may affect traffic operations and air pollution negatively. By reducing the number of roundabouts built in the US the rule would have a negative impact on traffic safety in the US in general and it would increase the crashes and injuries of the disabled population circulating in vehicles. I think also that the rule is premature since we have no experience in these types of installations and we have not tested other design, technological or pavement devices that would help visually impaired pedestrians to feel more comfortable crossing roundabout approaches.
Thanks for the opportunity to let us comment on these important guidelines. Please feel free to call me [...] if you have any questions.
Georges Jacquemart, P.E., AICP
Buckhurst Fish & Jacquemart, Inc.
index previous comment next comment