Safety-in-numbers is a phenomenon whereby the crash risks of road users decrease when their numbers increase. Although several previous studies have confirmed safety-in-numbers at a microscopic level (e.g., intersection), few studies have investigated safety-in-numbers at a macroscopic level (or zonal level). In this study, safety-in-numbers is investigated at a larger scale unit, the metropolitan statistical area (MSA), which is usually composed of multiple counties in the U.S.A. Various pedestrian and bicyclist exposure data were obtained from the U.S. National Household Travel Survey (i.e., trips, miles, and hours). A series of Bayesian Poisson lognormal models confirm safety-in-numbers with the different exposure variables at a large-scale geographic level (i.e., MSA). The findings imply that regional travel behavior and cultures of respect for vulnerable road users play a key role in determining the level of pedestrian and bicyclist safety. In addition, the results reveal other factors important to vulnerable road user involved crashes, including but not limited to the climate, demographic, socioeconomic, and travel characteristics of the study regions.
Investigation of Safety-in-Numbers for Pedestrians and Bicyclists at a Macroscopic Level with Various Exposure Variables
Transportation Research Record
Transportation Research Record: Journal of the Transportation Research Board ; 2674 , 12 ; 568-580
2020-10-10
Article (Journal)
Electronic Resource
English
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