New study on the impact of transportation infrastructure on bicycling safety
From the peer-reviewed literature; just published in the Environmental Health Journal by five researchers from the University of British Columbia:Methods
We 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).
Results
The 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.
Conclusions
Evidence 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.
More selected quotes:
Bicyclists are vulnerable because they must frequently share the same infrastructure with motorized vehicles, and yet bicycles offer their users no physical protection in the event of a crash. In addition, the mass of a typical automobile is at least an order of magnitude greater than a bicycle plus its rider, and motorized vehicles have top speeds that are considerably faster than bicycles. As a result, bicycle riders who are involved in a crash are exposed to a much higher risk of injury compared to motor vehicle users (with the exception of motorcycle riders).
In this paper we review the evidence on how different types of transportation infrastructure affect bicyclists’ safety. This paper is organized as follows: first we provide an overview of bicycling safety and ridership. Next we offer definitions of, and alternative terminology for, the transportation infrastructure used by cyclists that might be expected to influence their safety (Table 1). We describe our literature search methodology and the inclusion and exclusion criteria, and present the results of the search in two detailed tables. Table 2 describes studies that assess the safety of intersections for cyclists, and Table 3 describes studies related to straightaways (i.e. roads, lanes, paths). We conclude by discussing the findings of this review, critiquing the methodological approaches used, and offering recommendations for future research.
The principal trend that emerges from the papers reviewed here is that clearly-marked, bike-specific facilities (i.e. cycle tracks at roundabouts, bike routes, bike lanes, and bike paths) were consistently shown to provide improved safety for cyclists compared to on-road cycling with traffic or off-road with pedestrians and other users. Marked bike lanes and bike routes were found to reduce injury or crash rates by about half compared to unmodified roadways. The finding that bicycle-specific design is important applies also to intersections with roundabouts, where it was found that cycle tracks routing cyclists around an intersection separately from motor vehicles were much safer than bike lanes or cycling with traffic. It has been suggested that the reason for high rates of bicycle-motor vehicle collisions at intersections is that motor vehicle drivers may be making “looked-but-failed-to-see” errors, whereby they search for oncoming motor vehicles but do not recognize that a cyclist is approaching because they are not looking for them [40].
abstract
provisional full report (pdf)
Source: http://www.bikeforums.net/showthread.php?threadid=600133
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