Comment 78172

By highwater (registered) | Posted June 08, 2012 at 09:36:36 in reply to Comment 78156

That doesn't change the fact that the same (or very similar) results were found elsewhere by other studies.

In her 2009 book One-way to Two-way Street Conversions as a Preservation and Downtown Revitalization Tool, Meagan Elizabeth Baco has this to say about the 1998 article you reference above:

Pedestrian safety has always been a concern for traffic engineers. At the time of many two-way to one-way conversions, it was believed that one-way streets offered several advantages to pedestrians. The main principle of this promotion was based on the need of both drivers and pedestrian to only be aware of traffic traveling in one direction. There are also sources that contend there are fewer vehicle/pedestrian conflict points in a one-way system. An article in the Journal of the Institute of Transportation Engineers in 1998 calculated that there are either two or four conflict points in a one-way system depending on the number of lanes and type of turns allowed, up to 24 conflict points of any two-way configuration Furthermore, because vehicles only travel in one direction, both head-on and left-turn accidents will dramatically decrease. It has been stated that traffic accidents involving both vehicle/vehicle and vehicle/pedestrian conflicts can decrease between 10 to 50 percent if one-way streets are employed.

While there are indicators for the level of safety provided to pedestrians on one-way streets, there is a similar amount of evidence that contradicts that conclusion. The Traffic Engineers Handbook published by the Institute of Transportation Engineers indicates, “vehicles turning left out of one-way streets appear to hit pedestrians significantly more frequently than do all other turning vehicles.” Furthermore, in an article published in the Journal of the Institute of Transportation Engineers in 2004, a computer model was used to compare one-way and two-way networks and concluded that on one-way streets, vehicles travel at higher speeds, have a lesser average delay, and stop less often, and because of these attribute are not safe for pedestrians.

Superficially, it would seem that crossing single direction of traffic on one-way streets is preferable to crossing a two-way street. As is often the case, the conventional wisdom is wrong. In fact, crossing a one-way street presents greater difficulties to the pedestrians than crossing a two-way street. The explanation lays in the greater numbers of different vehicle/pedestrian conflict sequences that are encountered in crossing a one-way street.

Analysis of vehicle/pedestrian conflict points by those advocating for two-way streets has been calculated as two possible sequences for conflicts at a two-way street intersection and sixteen possible conflict sequences at one-way intersections. This is a much different conclusion than that previously presented from the article “One-Way Streets Provide Superior Safety and Convenience.” It appears that with the manipulation of specific intersection criteria it is possible to determine a far different number of vehicle/pedestrian conflicts. The individual intersections in commercial districts must be evaluated on a case-by-case basis to create an accurate measure of pedestrian safety.

While the number of vehicle/pedestrian conflicts and the rate of accidents cannot be unequivocally determined until the traffic pattern is determined and implemented, there are indications that two-way streets are safer. As noted earlier, two-way streets, regardless of posted speed limit tend to have slower vehicular speeds. A decrease in vehicular speed decreases both the total number of collisions and because of lower speeds can decrease the seriousness of those collisions.

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