Saturday, 7 January 2012

Recent academic research on cycling safety

The annual conference of the Transportation Research Board in the US features a huge number of papers and presentations across the whole spectrum of transport studies, and in recent years has included a good few about cycling safety. I looked through the papers from the 2011 conference and the abstracts for the upcoming 2012 one and found some interesting stuff, summarised below.

First, from the 2011 conference:
Bicycle Route Choice Model Developed from Revealed-Preference GPS Data (Broach et al)
Using an analysis of bike-mounted GPS data, finds that "cyclists are sensitive to the effects of distance, turn frequency, slope, intersection control, and traffic volumes. In addition, cyclists appear to place relatively high value on off-street bike paths, enhanced neighborhood bikeways (bicycle boulevards), and bridge facilities."
Disaggregate Exposure Measures and Injury Frequency Models of Cyclist Safety at Signalized Intersections (Miranda-Moreno et al)
Analysing data on cycle collisions and traffic flows, finds that "cyclist collisions were sensitive to changes in both cyclist and motor vehicle flows. A 10% increase in bicycle flow was associated with a 4.4% increase in the frequency of cyclist injuries. A 10% increase in the total number of motor vehicles that passed through the intersection would result in a 3.4% increase in cyclist injury occurrence."
The impact of bicycle lane characteristics on bicyclists' exposure to traffic-related particulate matter (Kendrick et al)
This one's about whether on-street or segregated cycling facilities expose cyclists to more air pollution. "Ultrafine particle exposure concentrations are compared in two settings: (a) a traditional bicycle lane adjacent to the vehicular traffic lanes and (b) a cycle track design with a parking lane separating bicyclists from vehicular traffic lanes. Traffic measurements were made alongside air quality measurements. It was observed that the cycle track design mitigates ultrafine particle exposure concentrations for cyclists."
Cyclist safety on bicycle boulevards and parallel arterial routes in Berkeley, California (Minikel)
Compared cycle collision rates on main arterial routes with 'bicycle boulevards', traffic-calmed side streets signed and improved for cyclist use. Found that "collision rates on Berkeley's bicycle boulevards are two to eight times lower than those on parallel, adjacent arterial routes. The difference in collision rate is highly statistically significant, unlikely to be caused by any bias in the collision and count data, and cannot be easily explained away by self-selection or safety in numbers."
And now here are a couple of papers due to presented in the 2012 conference this January:
Exploring Factors Influencing Bicyclists' Perception of Comfort on Bicycle Facilities (Li et al)
Detailed survey of cyclists in Nanjing finds that "the environmental factors significantly influencing bicyclists' perception of comfort included the width of path, presence of grade, presence of bus stop, physical separation from pedestrians, surrounding land use, and bicycle flow rate. For on-street bicycle lanes, the contributing factors associated with perception of comfort included the width of bicycle lane, width of curb lane, presence of grade, presence of bus stop, amount of occupied car parking spaces, bicycle flow rate, motor vehicle flow rate, and rate of use of electric bicycles. The results suggested that bicyclists perceived a higher average comfort on physically separated bicycle paths as compared to on-street bicycle lanes."
Safety of Urban Cycle Tracks: Review of the Literature (Thomas)
Review of studies into cycle tracks from various countries concludes that "one-way cycle tracks are generally safer than two-way and that, when effective intersection treatments are employed, constructing cycle tracks on busy streets reduces collisions and injuries. The evidence also suggests that, when controlling for exposure and including all collision types, building one-way cycle tracks reduces injury severity even when such intersection treatments are not employed."
I think if there's an overall conclusion to draw from these it's that cycling facilities which don't require cyclists to mix with motor vehicles are likely to be significantly safer, for reasons of air quality as well as reduced collision risk (which I think most people accept anyway).

1 comment:

  1. you'd be amazed how many people still think that separating bikes from traffic increases risk - including the CTC. Mainly citing John Franklin's research page. It will be interesting to get the text of that literature review.


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