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

Abstract

BackgroundBicycling has the potential to improve fitness, diminish obesity, and reduce noise, air pollution, and greenhouse gases associated with travel. However, bicyclists incur a higher risk of injuries requiring hospitalization than motor vehicle occupants. Therefore, understanding ways of making bicycling safer and increasing rates of bicycling are important to improving population health. There is a growing body of research examining transportation infrastructure and the risk of injury to bicyclists.MethodsWe reviewed studies of the impact of transportation infrastructure on bicyclist safety. The results were tabulated within two categories of infrastructure, namely that at intersections (e.g. roundabouts, traffic lights) or between intersections on "straightaways" (e.g. bike lanes or paths). To assess safety, studies examining the following outcomes were included: injuries; injury severity; and crashes (collisions and/or falls).ResultsThe literature to date on transportation infrastructure and cyclist safety is limited by the incomplete range of facilities studied and difficulties in controlling for exposure to risk. However, evidence from the 23 papers reviewed (eight that examined intersections and 15 that examined straightaways) suggests that infrastructure influences injury and crash risk. Intersection studies focused mainly on roundabouts. They found that multi-lane roundabouts can significantly increase risk to bicyclists unless a separated cycle track is included in the design. Studies of straightaways grouped facilities into few categories, such that facilities with potentially different risks may have been classified within a single category. Results to date suggest that sidewalks and multi-use trails pose the highest risk, major roads are more hazardous than minor roads, and the presence of bicycle facilities (e.g. on-road bike routes, on-road marked bike lanes, and off-road bike paths) was associated with the lowest risk.ConclusionEvidence is beginning to accumulate that purpose-built bicycle-specific facilities reduce crashes and injuries among cyclists, providing the basis for initial transportation engineering guidelines for cyclist safety. Street lighting, paved surfaces, and low-angled grades are additional factors that appear to improve cyclist safety. Future research examining a greater variety of infrastructure would allow development of more detailed guidelines.

Infrastructure and spatial effects on the frequency of cyclist-motorist collisions in the Copenhagen Region

“…It should also be noted that the findings of the current study extend the discussion by underlying the importance of the infrastructure in suburban areas where the separation between cyclists and motorists is even more beneficial because of the risk inherent in the higher speeds of the vehicles (e.g., 31,32). Findings about intersections being problematic are also in general in line with previous research (16,21,22), and also in this case they extend the current knowledge by emphasizing in particular that the effect is less marked in suburban areas than in urban ones.…”

“…Non-linearity is observed also with the vehicle traffic, and again as the traffic is expressed as vehicle × km and the parameter is significantly lower than 1, this non-linearity suggests that the crash rates diminish when vehicular traffic augments. This finding is not surprising, especially when considering that congestion has been generally related to lower crash rates because of the lower speeds and the consequent higher margins of error in recognizing a potential conflict (e.g., 16,18,23).…”

“…While some evidence points in the direction of cycling offering advantages because of the physical activity that reduces the health risks inherent to a sedentary life (e.g., 9,10,11), other evidence points in the direction of cycling bringing along negative effects because of the exposure to traffic pollution and crash risk (e.g., 12,13,14). When considering that the crash risk on a bicycle is definitely higher than the one on a motorized vehicle (e.g., 15,16,17) and factoring that it is the most significant disincentive to cycling (e.g., 18,19,20), investigating the factors contributing to the risk of being involved in a crash while riding a bicycle assumes a fundamental role for urban and transport planners aiming to increase the appeal of their cities and regions to potential cyclists.…”

“…In particular, a great deal of attention has been posed to infrastructure characteristics and specific conditions leading to a high number of conflicts between cyclists and other road users. Intersections and roundabouts have been often identified as blackspots for cyclists, with particular problems in signalized intersections or roundabouts replacing other types of intersections (e.g., 16,21,22,23). Interruptions to the traffic flow such as the presence of public transport stops or the adoption of traffic calming measures have been generally identified as problematic for cyclists, with specific hindrances linked to the interaction with other road users (e.g., 22,24,25).…”

Risk Factors for Bicycling Injuries in Children and Adolescents: A Systematic Review

“…27 Research examining transportation infrastructure and bicycling injury risk is on the rise, and a 2009 systematic review suggests that bike-specific infrastructure such as bike lanes and bike paths reduce bicycling injury risk while major roads, multiuse trails, sidewalks, and multilane roundabouts without a separate bike lane increase risk. 25 Because the 2009 review examined research on bicyclists of all ages, there is a research gap regarding transportation infrastructure (the bicycling environment) and bicycling injury risk in children and adolescents. We undertook this systematic review to examine the effects of individual and environmental factors on bicycling injury risk in children and adolescents.…”