Safer cycling and the urban road environment: A case control study
Introduction
Cycling is being promoted as a method of active transport in Europe, North America and Australia in response to dealing with rising congestion, and to encourage more physical activity in increasingly sedentary populations. While several OECD countries have seen decreasing numbers of bicycle crashes, this decrease is lower than for crashes involving other road users (OECD/ International Transport Forum, 2013). In addition, countries like Australia and New Zealand have seen increases in cyclist injuries over the last decade (Henley and Harrison, 2012; OECD/ International Transport Forum, 2013; Henley and Harrison, 2015). This trend suggests that cycling safety improvements are lagging behind the improvements occurring in other areas of road safety. Previous research has reported that most bicycle crashes occur in urban areas (Watson and Cameron, 2006) with crashes involving motor vehicles resulting in the most serious injuries among cyclists (Haileyesus et al., 2007; Chong et al., 2010) however, this may be due to the under-reporting of bicycle crashes to Police which do not involve a motor vehicle (Shinar et al., 2018). Other studies using hospitalisation data in Australia have found that injuries associated with on-road single-vehicle bicycle crashes were as severe as multi-vehicle crashes (Boufous et al., 2013).
There has been a plethora of research examining crashes involving cyclists, however many studies have focused on behavioural characteristics. The majority of studies examining road environment-related risk factors for bicycle crashes have been conducted in Europe which has quite different cycling road environments to Australia or North America. Many cities in Europe, where cyclists are fully separated from traffic in higher speed environments and lower speed roads function as shared spaces designed with cyclists in mind, have much higher cycling participation rates than Australia. However, the United States is more similar to Australia in that there is a dominant ‘car culture’ with minimal infrastructure provided for cyclists. Perth has a warm climate and generally flat topography, making commuter and recreational cycling popular. It has a network of off-road bicycle paths (shared with pedestrians) located largely on commuter routes however on-road riding (in traffic) is still common due to issues with the connectivity of bicycle paths.
Previous research has consistently reported that a greater number of bicycle crashes occur at intersections (Kaplan and Prato, 2013; Poulos et al., 2015). However there has been mixed findings regarding injurious bicycle crashes at an intersection in the presence of signalisation (traffic lights). One Canadian study found nearly five times greater risk for an injury at signalised intersections compared to non-signalised intersections (Strauss et al., 2014), while other research reported higher crash risk at priority control intersections (Harris et al., 2013; Rash-ha Wahi et al., 2018). A large study in Belgium, using a decade of crash data found that the crash risk for cyclists at roundabouts was even worse than at signalised intersections (Daniels et al., 2009). A Danish study also reported an increase of 65% and 40% in the number of crashes and cyclist injuries respectively, after intersections were converted to roundabouts (Jensen, 2013). While roundabouts may be associated with increased vehicular safety (Jurewicz et al., 2015), the opposite seems to be true for cyclists. Consistent research also suggests that the presence of on-road cycling facilities (bicycle lanes), whilst not as safe as dedicated off-road facilities, may in fact be a compromise to the riskier option of shared off-road facilities (De Rome et al., 2014; Poulos et al., 2015). Bicycle lanes in combination with roundabouts however are associated with a significant increase in bicycle crashes, with additional conflict points and reduced visibility created by the roundabout design (Jensen, 2013; Mulvaney et al., 2015). A recent Cochrane systematic review of road environment factors and cycling injuries concluded that there is a lack of high-quality evidence upon which to draw inferences on the effect of infrastructure on bicycle crashes (Mulvaney et al., 2015). Further investigation is required into the association between intersection control type and bicycle crashes in countries outside of Europe. Importantly, other road environment elements need to be examined in order to provide insights for designers and engineers who are increasingly having to deliver road environments that accommodate, safely, vulnerable roads users such as cyclists. Therefore the aim of this study was to identify features of the road environment that increased the risk of an on-road bicycle crash in Perth, Western Australia (WA).
Section snippets
Study design
A case-control study was undertaken which examined the association between road environemnt factors at sites where cyclists had experienced a bicycle crash resulting in hospitalisation, compared to sites where cyclists had not been involved in a bicycle crash, in Perth, Western Australia.
Ethics approval was obtained from Curtin University and the four recruiting hospitals. All participants provided written consent.
Case participant recruitment
Recruitment for case participants occurred between September 2014 and December
Participant demographics and cycling exposure
The majority of cases (58%) and controls (75%) had university degrees. Those who had university degrees were about half as likely to be involved in a crash (unadjusted OR: 0.43, 95% CI: 0.23, 0.83, P = 0.012). The majority of controls (88%) and cases (70%) were Australian. Crash risk was 3 times greater for those who were of a different nationality, compared to those who were Australian (unadjusted OR: 3.00, 95% CI: 1.41, 6.38, P = 0.004). The majority of controls (84%) and cases (60%) were in
Discussion
This is one of the first in-depth crash studies to examine the road-environment related risk factors for bicycle crashes resulting in hospitalisation in Perth, Australia. Several road-environment related factors were associated with an increased risk of bicycle crashes resulting in a hospitalisation which included roundabouts and traffic lights at intersections and roads with an incline at midblock sites.
This study found that roundabouts increased the risk of a crash compared to priority
Conclusion
This study highlighted the risk of roundabouts, traffic lights and roads with an incline for bicycle crashes. Treatments that reduce vehicle speeds and encourage cyclists to claim the lane at roundabouts as well as careful road design and road maintenance at traffic lights may reduce the risk of crashes for cyclists. While it is impossible to remove hills and slopes from the topography, it is possible to select routes to target for bicycle infrastructure which are predominantly level.
In
Funding
This study was funded by an Australian Research Council Linkage Grant (LP130100380) to the University of Melbourne, Monash University, Curtin University, Amy Gillett Foundation, Main Roads Western Australia, Portland State University, Transport Accident Commission (TAC), VicRoads and We Ride (previously Cycling Promotion Fund). Prof Stevenson is supported by a National Health and Medical Research Council Fellowship (APP1136250) and Dr Marilyn Johnson is supported by an Australian Research
Acknowledgements
The authors would like to acknowledge Denice Wallis for her work identifying and recruiting eligible cyclists from trauma hospitals in WA for this study.
References (29)
- et al.
Relative injury severity among vulnerable non-motorised road users: comparative analysis of injury arising from bicycle-motor vehicle and bicycle-pedestrian collisions
Accid. Anal. Prev.
(2010) - et al.
An exposure based study of crash and injury rates in a cohort of transport and recreational cyclists in New South Wales, Australia
Accid. Anal. Prev.
(2015) - et al.
Under-reporting bicycle accidents to police in the cost tu1101 international survey: cross-country comparisons and associated factors
Accid. Anal. Prev.
(2018) - et al.
Multimodal injury risk analysis of road users at signalized and non-signalized intersections
Accid. Anal. Prev.
(2014) - et al.
Single- versus multi-vehicle bicycle road crashes in Victoria, Australia
Inj. Prev.
(2013) Roundabout Design: Minimising Conflicts for Bicycle Riders
(2010)Roundabouts: why they are dangerous for cyclists and what can be done about it
Transp. Eng. Austr.
(2011)- et al.
Design types of cycle facilities at roundabouts and their effects on traffic safety: some empirical evidence
Velo-City Conference Brussels
(2009) - et al.
Bicycle crashes in different riding environments in the Australian Capital Territory
Traffic Inj. Prev.
(2014) - et al.
Cyclists injured while sharing the road with motor vehicles
Inj. Prev.
(2007)