This comment responds to a paper previously published in this journal (volume 95, number 9, pp. 237-239) entitled, "Pedestrian Clearance Intervals," by J. Stevenson. The current paper suggests that Stevenson does not discuss the nature of the actuated traffic signal and the pedestrian's active role in determining the variable timings at that type of intersection. A brief overview of the current situation in traffic signal timing are discussed, including pretimed traffic lights, traffic-actuated intersections and semi-actuated intersections. These complex timing schemes can complicate access for blind travelers, particularly in the absences of substantial regular traffic volumes. The possible variations in intersection timing and actuation make it important to contact the local traffic engineers to get accurate information about signal timing and individual intersections. If blind pedestrians try to cross arterial streets using the standard rule of "near parallel surge" without getting a pedestrian phase, they often are caught by short timings. Rather than simply lengthening the pedestrian clearance interval as a strategy to provide safer crossings for blind pedestrians, as Stevenson suggested, this paper argues that a more appropriate solution would be to provide blind pedestrians with information about the status of the traffic light. This would allow them to leave the curb as soon after the onset of the walk interval as it is safe to do so. This information could be provided to blind pedestrians by accessible pedestrian signals. Communication between the blindness community and traffic engineers, as well as access to updated information, is essential in designing intersections to make them easier for visually impaired pedestrians to use. (Author/publisher)
Abstract