Pedestrian and Bicyclist Exposure to Risk

Abstract

There is currently no commonly accepted or adopted measure of pedestrian and bicycle exposure to risk. Consequently, a large portion of the field of pedestrian and bicycle safety is lacking an adequate means to evaluate the effectiveness of its efforts. The current study presents a proposed metric for measuring pedestrian and bicycle exposure to risk: hundred million pedestrian or bicycle miles of roadway (or other motor vehicle shared facility) traveled. A method for implementing the proposed exposure metric is described for eight shared-facility types characteristic of the urban environment of Washington, D.C. These facilities include three types of intersections, midblock road segments, driveways, alleys, parking lots, parking garages, school areas, and areas with playing, dashing, and working in the roadway. The methodology is then used to calculate the annual pedestrian and bicycle exposure for the city for the calendar year 2007. The results of these calculations revealed 0.82 hundred million miles for pedestrian exposure and 0.37 hundred million miles for bicyclist exposure. In this way both the feasibility and scalability of the proposed metric were successfully demonstrated for a relatively large urban environment. Thus the proposed metric has the potential to eliminate one of the major obstacles in the pedestrian and bicycle safety field, the lack of adequate exposure data. Although further refinement and validation are still needed, the proposed metric provides a possible initial foundation to develop a national unit of risk exposure for pedestrians and bicyclists.

Perception of Pedestrian Traffic Signals by Pedestrians with Varying Levels of Vision

“…high symbols was made based on evidence provided by others that suggested that even 9 in. symbols would pose considerable challenges to pedestrians with the simulated acuities used here and for the included crossing distances (13). …”

“…Results of these studies were contradictory. Molino, Katz, Kennedy, and Hermosillo (13) investigated the legibility distances for reading countdown displays. They used an almost exclusively analytical approach in which they predicted the maximum distance from which countdown numerals of various heights would be legible to pedestrians with various levels of visual acuity.…”

“…They used an almost exclusively analytical approach in which they predicted the maximum distance from which countdown numerals of various heights would be legible to pedestrians with various levels of visual acuity. The authors based their predictions on current signals standards regarding luminance and contrast, and on an average legibility index (i.e., the number of feet of viewing distance per inch of letter height) based upon those used or recommended by the MUTCD, the United States Sign Council (USSC), and the American National Standards Institute (ANSI) (for details, see Molino et al (13)). Molino et al (13) predicted that for those at the upper end of the range of normal vision by U.S. standards (20/40), 6 in.…”

“…The authors based their predictions on current signals standards regarding luminance and contrast, and on an average legibility index (i.e., the number of feet of viewing distance per inch of letter height) based upon those used or recommended by the MUTCD, the United States Sign Council (USSC), and the American National Standards Institute (ANSI) (for details, see Molino et al (13)). Molino et al (13) predicted that for those at the upper end of the range of normal vision by U.S. standards (20/40), 6 in. high numerals would be legible up to 75 ft. For 20/70 acuity, the WHO boundary for category 0 visual impairment (mild or no visual impairment), Molino et al (13) predicts that 6 in.…”

“…Molino et al (13) predicted that for those at the upper end of the range of normal vision by U.S. standards (20/40), 6 in. high numerals would be legible up to 75 ft. For 20/70 acuity, the WHO boundary for category 0 visual impairment (mild or no visual impairment), Molino et al (13) predicts that 6 in. high numerals would be legible up to only 43 ft.…”