Safety of cycling infrastructure
A higher modal share of people cycling is correlated with lower incidences of cyclist fatalities, leading to a "safety in numbers" effect though some contributors caution against this hypothesis.
Studies generally show an increase in collisions at junctions, especially where cyclists are travelling in the direction opposite to the flow of traffic (e.g. on two-way cycle tracks).
[9] One major reason for the inability to draw definite conclusion may be that facilities with different risks are often categorized together so that off-road paths – paved or unpaved, bicycle-only or multi-use – were lumped together, as found by research at the Cycling in Cities program at the University of British Columbia.
[10] A study by Peter L. Jacobsen found that as cycling and walking levels increase, the chance that a given cyclist will be struck by a motor vehicle actually decreases.
Jacobsen found that doubling the number of cyclists on the road tends to bring about a one-third drop in the per-cyclist frequency of a crash with a motor vehicle.
[12] A study of the accident impacts of re-engineering bicycle crossings in the Swedish city of Gothenburg appears to corroborate those findings by attributing collision rate reductions in part to significant increases in cyclist volumes at the treated sites.
[18] In the Netherlands, for example, drivers know to expect a high volume of cyclist traffic and bicycle paths are widespread and (in the cities) closed to scooters.
[23] They found that "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."
Aultman-Hall et al. admitted that the limitations to the data and a fuller analysis needed "bicycle travel exposure information and the use of more than just collision databases".
The Committee had supposed that many collisions would occur when cars overtook bicycles and that such a finding would help to justify their plans to offer segregation between junctions.
In second study by Cross, he argues that, "although a reduction in overtaking accidents may not be sufficient justification for the widespread use of on-street bicycle lanes, it is possible that their cost could be justified when considering all the problem types that might be positively affected by such facilities.
"[32] A 1988 British medical study suggested that their data indicated that cycle lanes were safer than ordinary roads, reducing the kilometre rate of collisions.
[38] British cycling safety educator John Franklin has argued that the vast majority of research implies increases in the rate and severity of car-bicycle collisions due to such segregation, based on an overview of studies published up to 1999.
He attributes this to poor user discipline on the redways, under a false illusion of safety, which also spills into other areas, such as increased footway cycling.
They found such bike-only facilities had lower risk than cycling on-road with motor traffic as well as off-road with pedestrians on sidewalks or multi-use paths.
For instance, recent planning guidelines in the US advise that cycle tracks drop to a bike lane before arriving at an intersection to increase the visibility of cyclists.
[1] According to one literature review, clearly-marked, bike-specific facilities are consistently shown by studies on the topic to improve safety for cyclists compared to riding with traffic or off-road with pedestrians.
[48] A 2020 study in Toronto, Canada, found that cycle track implementation is linked with reduced cycle-motorist collisions after adjusting for increased volume.
[50] In the UK, cycling collision data recorded by police indicates that at non-junction locations, where a cyclist was struck directly from behind there was an overall fatality rate of 17%.
The rate of fatality increases with speed limit of the road: The use of appropriately designed segregated space on arterial or interurban routes appears to be associated with reductions in overall risk.
[38] A 1994 study in Palo Alto, California by A. Wachtel and D. Lewiston[57] concluded that "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.
It concluded "the aim of a well-designed roadway system should be to integrate bicycles and motor vehicles according to the well-established and effective principles of traffic law and engineering, not to separate them.
If the non-intersection crash data is included, as Lusk et al. calculated in their study, it appears that sidewalk bikeways carry half the risk of the street, for bicyclists riding in the same direction as traffic.
Lusk et al. claim that the "Wachtel and Lewiston data, when corrected to include non-intersection crashes, corroborate our findings that separated paths are safer or at least no more dangerous than bicycling in the street.
[59][a] A 2017 Dutch study found that the likelihood of crashes at unsignalised intersections with one-way cycle paths is 45% lower when the track is deflected between 2 and 5 metres from the kerb.
Examples of these include the use of special road markings, e.g. "sharks teeth" or "elephants footprints", and treatments using red, green or blue coloured tarmac.
In 2002, engineers proposing a sidepath scheme in the Irish university city of Galway stated that cyclists would be required to dismount and "become pedestrians" at every junction on the finished route.
[63] A 2005 paper on German roundabout design practice states "Cycle lanes at the peripheral margin of the circle are not allowed since they are very dangerous to cyclists".
[67] The New York City Department of Transportation implemented a bicycle path and traffic calming pilot project for Prospect Park West in Brooklyn in 2010 and published their results in early 2011.
[71] In addition, it has been shown that in western countries the health benefits of regular cycling significantly outweigh the risks due to traffic danger.
