There is debate over the safety implications of cycling infrastructure (e.g. cycle tracks, protected intersections). Recent studies generally affirm that segregated cycle tracks have a better safety record between intersections than cycling on major roads in traffic. Furthermore, cycling infrastructure tends to lead to more people cycling. 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. On the contrary, older studies tended to come to negative conclusions about mid-block cycle track safety.
However, the implications for road safety of cycle tracks at intersections is disputed. 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). Protected intersection designs generally improve safety records over non-protected junction types.
A 2006 report by the National Cooperative Highway Research Program in the US concludes that "bicycle safety data are difficult to analyze, mostly because bicycle trip data (and thus accident probability per trip) are hard to uncover".NCHRP Report 552, 2006, "Guidelines for Analysis of Investment in Bicycle Facilities", National Cooperative Highway Research Program, Transportation research Board of the National Academies, page F-1 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.
Safety in numbers effect 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.(PDF) Safety in numbers: More walkers and bicyclists, safer walking and bicycling This pattern is consistent across communities of varying size, from specific intersections to cities and countries, and across time periods. 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. By the same token, tripling the rate of cycling cuts the crash rate in half. 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. Studies have demonstrated that cities with high levels of cycling tend to have better traffic safety records for all road users. However, the same study also suggests that the 'safety in numbers' effect is not as important in improving safety records as building cycling infrastructure. Improving bike infrastructure with more separated facilities leads to lower fatalities and more safety for all road users.
Furthermore, countries which have higher levels of cycling have lower fatality rates for cyclists than countries which do not. The table below shows the modal split share for cycling compared with the cycling fatality rate in the Netherlands, Germany and the United States.
+ Cycling safety by modal split share by country (Pucher, 2001) Country Cycling modal split share Fatality rate per 100 million bike trips 28% 1.6 12% 2.4 <1% 26.3
A unpublished paper from the Helsinki City Planning Department reported that the Netherlands, Sweden and Denmark, known for cycle networks and one-way cycle tracks, had the lowest rates of cyclist fatalities, while countries without such extensive networks such as Great Britain and Italy reported higher rates.
There is evidence that one of the main factors influencing the individual safety of cyclists is the number of cyclists using the roads, commonly called the safety in numbers effect. Cycling facilities increase the perception of safety, leaving aside the evidence supporting or detracting from their actual risk. Cycling increases on routes with cycling facilities, particularly if they are separated cycle tracks. With greater numbers of cyclists in relation to motorists, the safety in number effect is seen.
Detractors argue that the most prominent examples of "successful" cycle networks were implemented in towns that already had significant numbers of cyclists.Getting rid of the Cyclists: Frank Urry and the 1938 DoT Advisory Committee by Jeremy Parker, Bikereader.com (accessed 27 January 2007) 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. Due to this expectation, some argue, the number of car-bike collisions with serious consequences is not alarmingly high in the Netherlands. In such cases, it is speculated that an existing large cycling population might already exert a "safety in numbers" effect, and it is this, rather than their diversion onto off-road tracks, that accounts for the better safety record. More people might start cycling if the perceived safety of doing so improved sufficiently.
Bhatia and Wier caution against the "Safety in Numbers" hypothesis, because it is unsubstantiated. The claim that larger numbers changes motorist behaviour is judged as premature and the authors urge better research into the topic. A 2019 study of the relation between bicycling rates and road safety concluded that 'more bicyclists on the road is not as important as the infrastructure we build for them'.
In general
Aultman-Hall et al. produced a 1998 study based on a survey of Ottawa commuter cyclists and a survey of Toronto commuter cyclists. The surveys were conducted to create "estimates of travel exposure on roads, off-road paths and sidewalks". 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." The relative rates of collisions on the three different facility types, however, were not statistically significant in the Ottawa study. 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".
Studies that also found negative safety aspects of cycle tracks also come from Linderholm, Sweden, 1984Leif Linderholm: Signalreglerade korsningars funktion och olycksrisk för oskyddade trafikanter ─ Delrapport 1: Cyklister. Institutionen för trafikteknik, LTH: Bulletin 55, Lund 1984, In: »Russian Roulette« turns spotlight of criticism on cycleways, Proceedings of conference »Sicherheit rund ums Radfahren«, Vienna 1991. and from Jensen et al., Denmark 1997.Junctions and Cyclists, S.U. Jensen, K.V. Andersen and E.D. Nielsen, Velo-city '97 Barcelona, Spain
Opponents of segregated cycle facilities say that segregation of cyclists from fast or frequent motorized traffic increases crash and injury rates. For example, the author of a 2014 review of cycling safety concluded that the majority of studies showed increased crash and injury rates on segregated cycle facilities. He criticized the methodology of studies showing the opposite, including the Montreal study.A Review of cycle Track Safety Paul Schimek, 2014
A study on cycling safety in the Netherlands reviewed how the Dutch achieved an 80% reduction in the number of cyclists killed per distance cycled over a 30-year period. Some factors in this reduction were the establishment of a road hierarchy (the Dutch 'unbundling' approach) with separate routes for fast-moving motor traffic and slower-moving cycle traffic and an extensive network of separated bicycle paths and intersection treatments. The study highlighted not just the importance of infrastructure which takes cyclists off busy roads, but also takes motorists off less-suitable roads. The Netherlands' extensive motorway network shifts large amounts of traffic from city roads to spaces away from more vulnerable road users.
A 2019 study of the relation between bicycling rates and road safety found that cities with more protected cycle facilities correlates with better road safety records.
A study in Amsterdam found that cycle lanes incur nearly double the risk of cyclist crashes compared to cycle tracks. The absence of cycling facilities was not significant until streets with similar conditions are compared. For three given streets with similar conditions - one with cycle tracks, one with cycle lanes and one with no facilities - the risk of a crash is higher on a street with no facilities or cycle lanes rather than cycle tracks. Overall, the study reports a safety benefit of 50-60% fewer cycling crashes of cycle tracks over mixed traffic. Kerbside parking leads to increased crashes due to dooring and visibility obstructions.
A 2021 study confirmed an expectation that the presence of protected bike lanes is associated with significant improvement in biking safety. The model predicts that by adding bike lanes to non-local streets increases biking safety by 26% in a local area.
A 2026 data from NY confirms that during evening rush hours in NY "accounts for 33.7% of all bicycle crashes, representing the most dangerous time for NYC cyclists as heavy traffic combines with peak cycling commute volumes and reduced visibility during winter months." Overall, this data reports the risk injuries and collisions cyclist face when trying to commute in a busy city like NY or in other general busy cities with safety bike lane procedures in use. Despite all of the work done to prevent bicycle crashes the data states "nearly all two-thirds of all bicycle crashes 64.6% occur at intersections meaning that the main cause of all incidents are vehicles and cyclist being the primary safety challenges of bike lanes."
Between intersections
In the 1970s, the California Statewide Bicycle Committee commissioned Kenneth D. Cross to study car-bike collisions. 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. Unexpectedly, Cross found that only 0.5% of car-bike collisions had occurred between straight-ahead cyclists and overtaking straight-ahead motorists. Cross in 1977 had a contract with the National Highway Traffic Safety Administration (NHTSA) to produce an improved study (on a pseudo-random national sample), and the results were much the same. 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. There is virtually no doubt that off-street bicycle lanes would reduce the incidence of overtaking accidents, if such facilities were available and used by bicyclists who would otherwise be riding on roadways."
A 1988 British medical study suggested that their data indicated that cycle lanes were safer than ordinary roads, reducing the kilometre rate of collisions.