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Updated
April 2, 2007
This study is called “The Effects Of Roundabouts On Pedestrian Safety” prepared for the University of Tennessee at Knoxville, August 2002. The link is to a PDF. Below is what I consider the relevant excerpt:
http://stc.utk.edu/htm/pdf%20files/rndabt.pdf
Or download complete article here.
Roundabouts and Pedestrian Safety
What professional discussions lack, however, are definitive statistics for pedestrian safety at roundabouts. Indeed, the magnitude of the problem remains undefined, though appreciated. Hence, the proposal for this grant was written in mid 1999. Subsequently in mid 2001 NCHRP announced the project Applying Roundabouts in the United States7, a major effort to apply data and results from international sources to U.S. drivers, pedestrians and the highway environment.
For example, a typical roundabout reference like the FHWA Roundabout Design Guide (Chapter 2)1 gives explicit vehicular crash reduction statistics that are similar to those by Persaud. Yet, the Guide has no such data for pedestrians. The consultant for the Guide relies on the indirect surrogate measure of speed8. The consultant presents information showing that at the lower 20-mph speed of most roundabouts, the chance of a pedestrian being killed if hit by a vehicle is 15%. On the other hand, at conventional intersections where the speeds are typically 30 to 40 mph the chances of being killed if hit by a vehicle range from 45% to 85% (Figure1.3). Persaud reports that for his 24 case study intersections the pedestrian crash sample was too small to estimate safety effects2. An Australian study9 and a Scandinavian study10, however, report that roundabouts are safe for pedestrians. The Swedish Road Administration commissioned VTI (Swedish National Road & Transport Research Institute) to study accident and injury risks at roundabouts with different layouts in different traffic environments.
The limited amount of U.S. pedestrian safety data may be explained by the relative infrequency of pedestrian-vehicle crashes compared to vehicle-vehicle crashes. For example, NCDOT studies show that the heavily traveled Hillsborough Street near the campus of North Carolina State University has an average of about seven pedestrian crashes annually compared to about 300 vehicle crashes11. The paucity of pedestrian safety data may also be explained by documented intersections being located where little pedestrian activity occurs. Furthermore, unconventional intersections like roundabouts do not have easily identifiable categories in accident reports. Hence, what data that may exist cannot be identified in U.S. accident databases.
But therein lies the quandary. Relatively little pedestrian data exist compared to vehicle crash data; even less pedestrian crash data exist for roundabout treatments. Yet, roundabouts are often proposed for traffic calming in high pedestrian areas like Hillsborough Street, the traditional “front door” of NC State University’s campus12, 13. Similar high activity, pedestrian-oriented roundabout sites are in Colorado, Oregon, Vermont, Maryland, and Florida14. Yet, they are relatively new and there is little or no history of pedestrian accidents. However, some advocates for roundabouts point to the scarcity of pedestrian accident data as evidence of their efficacy as a safety treatment. In any event, there is a need to obtain more information about how roundabouts affect pedestrian safety. By doing so, the intent is to clarify pedestrian safety issues at roundabouts. Subsequently in 2001, TRB similarly recognized the need for more pedestrian safety information at roundabouts15.
Pedestrian Issues at Roundabouts
According to the FHWA Design Guide (Chapter 2) 2, roundabout splitter islands (Figure 1.2) provide refuge to pedestrians and allow them to cross one direction of traffic at a time. However, the crosswalks are set back from the yield line creating additional walking distance, and they usually occur between the first and second vehicles in the queue. Both situations are unusual for U.S. pedestrians. Indeed, anecdotal evidence leads to concerns that pedestrians may minimize their walk distance by taking short cuts across the central island and cause impatient drivers to challenge pedestrians.
Furthermore, pedestrian – vehicle right of way rules differ at roundabouts compared to traditional intersections. For example, North Carolina State Statute says that vehicles yield to pedestrians at traditional intersections. Roundabouts, which are not recognized by Statute, require pedestrians to yield to the vehicles.
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