Logistic Model for Rating Urban Bicycle Route Safety

Abstract

In response to renewed appreciation of the benefits of bicycling to the environment and public health, public officials across the nation are working to establish bicycle routes. During the past two decades a number of methods have been endorsed for the selection of "suitable" bicycle routes. These methods are limited in that they do not explicitly address bicycle safety nor do they reflect urban conditions. The purpose of this research is to develop an objective bicycle route safety rating model based on injury severity. The model development was conducted with a logistic transformation of bicycle crash data from Jersey City, New Jersey, for the period 1997 to 2000. The resulting model meets a 90% confidence level by using various operational and physical factors (traffic volume, lane width, population density, highway classification, and presence of vertical grades, one-way streets, and truck routes) to predict the severity of an injury that would result from a motor vehicle crash that occurred at a specific location. The modeled rating of the bicycle route's relative safety is defined as the expected value of the predicted injury severity. This rating is founded on the premise that safe routes produce less-severe crashes than do unsafe routes. The contribution of this research goes beyond the model's predictive capacity in comparing the safety of alternative routes by providing planners with an understanding, derived from objective data, of the factors that add to the route's safety, factors that reduce safety, and factors that are irrelevant.

Comparing the effects of infrastructure on bicycling injury at intersections and non-intersections using a case–crossover design

“…Downhill grade was associated with increased risk at both intersections and non-intersections, similar to findings elsewhere,11 39 40 probably affecting risk due to speed of travel and resulting force of impact. While the overall topography of a city is not modifiable, routes targeted for bicycle-specific infrastructure can be selected to minimise elevation changes to improve safety and simultaneously reduce exertion from uphill travel.…”

The impact of transportation infrastructure on bicycling injuries and crashes: a review of the literature

“…Two studies examined off-road bike paths and found reduced risks, ranging from 0.11 to 0.67 times the risk of cycling on minor roads [64,67]. Two studies that grouped paved and unpaved, bicycle only and multi-use urban trails in their off-road path category found elevated risks, 1.6 to 3.5 times higher than riding on-road [29,66,68]. Studies that examined unpaved off-road trails as a separate category found risks of injury 2.5 to 7.2 times higher than on-road cycling [61,65,66] and 8 to 12 times higher than bike routes, lanes, or paths [65,66].…”

“…Most studies that considered sidewalk-riding suggested that it is particularly hazardous for cyclists, with estimates of 1.8 to 16 times the risk of cycling on-road [29,66-68,71]. However one study found that the risk of traveling on the sidewalk was the same or lower than riding on residential streets [64].…”

“…Other investigators clearly defined their infrastructure terms, but grouped facilities that may have different injury risks. For example, the studies of Aultman-Hall et al [29,68] defined paths as "an off-road (usually multi-use) paved or unpaved path or trail," grouping paths for bikes only, which were found by others to have lower risks than cycling on roads [64,67], with unpaved trails, which were found by others to have higher risks [61,65,66]. Definitions of terminology are especially important in questionnaire-based studies to ensure that study participants are all answering with the same infrastructure in mind; photos can be helpful in this regard [33].…”

Route Infrastructure and the Risk of Injuries to Bicyclists: A Case-Crossover Study

“…Two studies have shown increased injury severity with increased grades. 41,42 Route grades may not seem modifiable, but bike routes can be located where grades are low (e.g., along abandoned rail beds). This would also improve route preference because steep slopes are a deterrent to cycling.…”