Saturday, August 11, 2012

Bicycle Infrastructure Studies for your reading pleasure

Ian Brett Cooper compiled this list on his blog and gave permission to post elsewhere. Here they are too, with acknowledgements to Ian for doing all the hard work. The text below the links are either excerpts from the studies or Ian's comments (not mine, nor do our opinions necessarily stay in lockstep ). I left them there from his site out of deference to Ian doing all the footwork. Go read the originals.

Bicycle Infrastructure Studies

Since the idea that bicycle infrastructure increases safety is pretty widely held, Ian Cooper compiled a list of studies of bicycle infrastructure, including links and what I think are the most interesting quotes. He thinks many people will be surprised by what the studies suggest:

1972 Deleuw, Cather and Co.: Davis Bicycle Circulation and Safety Study
"An additional problem is establishment of a visual relationship between motor vehicles and cycles on the sidewalk path on approaches to intersections."

1975 Kaplan: Characteristics of the Regular Adult Bicycle User
"Surprisingly, bicycle facilities where no motor vehicles are allowed showed the highest accident rate of any variable examined."

1977 Cross: A Study of Bicycle/Motor Vehicle Accidents (USA)
Possible bias in reporting, investigation. Study reaches no clear conclusions about the safety or otherwise of bicycle infrastructure, and many of the conclusions have been called into question by more recent studies. I think the study does remain useful thanks to its detailed crash type analysis.

1987 Grüne Radler review: Police Bicycle Crash Study (Berlin, Germany)
"...with increasing experience, it became ever clearer that the sidepaths are dangerous - more dangerous than riding in the roadway. There is a simple reason for this: the design and location of the sidepaths conflict with the most important principle of traffic safety, the slogan 'Visibility is safety'."

1992 Allgemeiner Deutscher Fahrrad-Club: Issues of Bicycling Safety
"Experts from different backgrounds at the Velo Secur traffic safety conference in Salzburg were united in the opinion that sidepaths in urban areas are entirely unsatisfactory in many ways, and should not be used."

1994 Gårder: Safety implications of bicycle paths at signalized intersections (Scandinavia)
"The conclusion that can be drawn so far from combining results shows that the most likely effect of introducing a cycle path is that the risk will increase by about 40% for a passing cyclist."

1994 Wachtel: Risk Factors for Bicycle-Motor Vehicle Collisions at Intersections (Palo Alto, California, USA)
"Bicyclists on a sidewalk or bicycle path incur greater risk than those on the roadway (on average 1.8 times as great), most likely because of blind conflicts at intersections... intersections, construed broadly, are the major point of conflict between bicycles and motor vehicles. Separation of bicycles and motor vehicles leads to blind conflicts at these intersections."

1997 Moritz: A Survey of North American Bicycle Commuters (USA and Canada)
Possible measurement bias: study claims increased safety on bicycle specific infrastructure, but the accident site data appears to be flawed - many of the accidents taking place while on bicycle paths or lanes may have been considered to be on the roadway, because only the final crash site was considered.

1998 Aultman-Hall: Commuter Cyclist On- and Off-Road Incident Rates (Ottawa-Carlton, Canada)
"The relative rates for falls and injuries suggest it is safest to cycle on-road followed by off-road paths and trails, and finally least safe on sidewalks... Results suggest a need to discourage sidewalk cycling, and to further investigate the safety of off-road paths/trails."

1998 Moritz: Adult Bicyclists in the United States (USA)
"Multi-use trails have a crash rate about 40% greater than would be expected based on the miles cycled on them while cycling on the sidewalk is extremely dangerous."

1998 OECD: Safety of Vulnerable Road Users (European Union)
"The most common conflicting areas between motorised traffic and vulnerable road users are at junctions... While cycle tracks have been found efficient in decreasing bicycle accidents on links, particularly on arterials, they create safety problems at junctions."

1999 Aultman-Hall: Bicycle Commuter Safety Rates (Toronto, Canada)
"The relative rates for falls and injuries suggest these events are least common on-road followed by off-road paths, and finally most common on sidewalks... These rates suggest a need for detailed analysis of sidewalk and off-road path bicycle safety."

1999 Franklin: Two Decades of the Redway Cycle Paths (Milton Keynes, UK)
"...the most alarming experience of the Redways is their accident record. Far from realising gains in safety, they have proved over many years to be consistently less safe than even the 'worst case' grid roads for adult cyclists of average competence. This is not an accolade for the grid roads, for their safety performance is not good in relation to lower speed roads of more traditional design. But the segregated Redways have proved to be worse. "

1999 Pasanen: The risks of cycling (Helsinki, Finland)
"At crossings, car drivers focus their attention on other cars rather than on cyclists... the risk of a crossing accident is 3-times higher for cyclists coming from a cycle path than when crossing on the carriageway amongst cars."

2000 Franklin: Cycle Path Safety: A Summary of Research (Worldwide)
"little evidence has been found to suggest that cyclists are safer on paths than on roads."

2002 Reid: The Roots of Driver Behaviour Towards Cyclists (UK)
"The tendency for drivers to criticise cyclists and to exonerate errors made by drivers can be explained by reference to Social Identity Theory... Drivers regard themselves as intending to behave cautiously around cyclists and yet feel pressurised by other drivers to behave incautiously... It was also notable that drivers rated cyclists as less considerate, even though the cyclist’s behaviour was identical, when encountering them at road narrowings... Cyclists are an ‘out’ group and their behaviour is considered to be inexplicable other than by reference to their status as cyclists."

2007 Jensen: Bicycle Tracks and Lanes, a Before - After Study (Copenhagen, Denmark)
"The safety effects of bicycle tracks in urban areas are an increase of about 10 percent in both crashes and injuries. The safety effects of bicycle lanes in urban areas are an increase of 5 percent in crashes and 15 percent in injuries. Bicyclists’ safety has worsened on roads where bicycle facilities have been implemented."

2008 Agerholm: Traffic Safety on Bicycle Paths (Western Denmark)
"So the main results are that bicycle paths impair traffic safety and this is mainly due to more accidents at intersections."

2009 Daniels: Injury crashes with bicyclists at roundabouts (Flanders, Belgium)
"Regarding all injury crashes with bicyclists, roundabouts with cycle lanes appear to perform significantly worse compared to... other design types"

2009 Reynolds: The Impact of Transportation Infrastructure on Bicycling Injuries and Crashes: A Review of the Literature
Cherry picking data: review claims increased safety on bicycle specific infrastructure, but the review cherry picks and misrepresents data - only the 2009 Daniels study (out of 26 studies reviewed) concerned bicycle specific infrastructure safety, and the review misrepresented its findings.

2011 Lusk: Risk of Injury for Bicycling on Cycle Tracks Versus in the Street (Montreal, Canada)
The infamous Lusk study. Selection bias: study claims increased safety on bicycle specific infrastructure, but its street comparisons are flawed - the streets compared were in no way similar other than their general geographic location. Busy downtown streets with multiple distractions per block were twinned with bicycle tracks on quieter roads with fewer intersections and fewer distractions.

2011 Reid: Infrastructure and Cyclist Safety (UK)
"...evidence suggests that the points at which segregated networks intersect with highways offer heightened risk, potentially of sufficient magnitude to offset the safety benefits of removing cyclists from contact with vehicles in other locations."

John Allen has an extensive set of reports and studies, available here:

John Franklin also has an extensive list, without direct quotes but with his commentary, available here:

Bicycling Life also has a set of interesting documents, available here:

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