Elsevier

Accident Analysis & Prevention

Volume 129, August 2019, Pages 342-349
Accident Analysis & Prevention

Safer cycling and the urban road environment: A case control study

https://doi.org/10.1016/j.aap.2019.05.032Get rights and content

Highlights

  • Roundabouts and traffic lights increased the risk of a bicycle crash at intersections.

  • Inclined roads increased the risk of a bicycle crash at midblocks.

  • Lower vehicle speeds and encouraging cyclists to claim the lane may reduce crashes at roundabouts.

  • Careful road design and maintenance may reduce bicycle crashes at traffic lights.

Abstract

This study aimed to identify features of the road environment that increased the risk of on-road bicycle crashes in Perth, Australia between 2014-2017. This case-control study used a combination of an in-depth crash study and naturalistic study to compare the road environment characteristics of 100 case (crash) sites and 300 control sites where no crash occurred using conditional logistic regression. For intersection sites, roundabouts (adjusted OR: 2.98, 95% CI: 1.18, 7.56) and traffic lights (adjusted OR: 3.86, 95% CI 1.29, 11.63) significantly increased the risk of a bicycle crash, compared to priority control/uncontrolled intersections. For midblock (non-intersection) sites, roads with an incline (upwards/downwards) significantly increased the risk of a crash (adjusted OR: 3.39, 95% CI: 1.02, 11.22), compared to level roads. 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.

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)

  • M.A. Harris et al.

    Comparing the effects of infrastructure on bicycling injury at intersections and non-intersections using a case–crossover design

    Inj. Prev.

    (2013)
  • G. Henley et al.

    Trends in Serious Injury Due to Land Transport Accidents

    (2012)
  • G. Henley et al.

    Trends in Serious Injury Due to Road Vehicle Traffic Crashes, Australia 2001 to 2010

    (2015)
  • Insurance Commission of Wa/ Wa Police

    Online Crash Reporting Facility

    (2017)
  • Cited by (0)

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