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Exposure-based cycling crash, near miss and injury rates: The Safer Cycling Prospective Cohort Study protocol(2012) Poulos, Roslyn; Hatfield, Julie; Rissel, Chris; Grzebieta, Raphael; McIntosh, Andrew SJournal ArticleIntroduction: There are clear personal, social and environmental benefits of cycling. However, safety concerns are among the frequently cited barriers to cycling. In Australia, there are no exposure-based measures of the rates of crash or ‘near miss’ experienced by cyclists. Design and setting: A prospective cohort study over 12 months, with all data collected via web-based online data entry. Participants: Two thousand adults aged 18 years and older, living in New South Wales (Australia), who usually bicycle at least once a month, will be recruited from March to November 2011. Methods: In the 12 months following enrolment, cyclists will be surveyed on 6 occasions (weeks 8, 16, 24, 32, 40, and 48 from the week of the enrolment survey). In these survey weeks, cyclists will be asked to provide daily reports of distance travelled; time, location and duration of trips; infrastructure used; crashes, near misses and crash-related injuries. Information on crashes and injuries will also be sought for the intervening period between the last and current survey. A subsample of participants will receive bicycle trip computers to provide objective measurement of distance travelled. Discussion: This study protocol describes the prospective cohort study developed to assess near misses, crashes and injuries among cyclists by time and distance travelled and by type of infrastructure used, with recruited participants entering data remotely using the internet. We expect to be able to calculate event rate according to exposure overall and for different infrastructure types and to report in-depth information about event causation.
Long term bicycle related head injury trends for New South Wales, Australia following mandatory helmet legislation(2012) Olivier, Jake; Walter, Scott; Grzebieta, RaphaelJournal ArticleSince the 1991 enactment of mandatory helmet legislation (MHL) for cyclists in New South Wales (NSW), Australia, there has been extensive debate as to its effect on head injury rates at a population level. Many previous studies have focused on the impact of MHL around the time of enactment, while little has been done to examine the ongoing effects. We aimed to extend prior work by investigating long-term trends in cyclist head and arm injuries over the period 1991–2010. The counts of cyclists hospitalised with head or arm injuries were jointly modelled with log-linear regression. The simultaneous modelling of related injury mechanisms avoids the need for actual exposure data and accounts for the effects of changes in the cycling environment, cycling behaviour and general safety improvements. Models were run separately with population counts, bicycle imports, the average weekday counts of cyclists in Sydney CBD and cycling estimates from survey data as proxy exposures. Overall, arm injuries were higher than head injuries throughout the study period, consistent with previous post-MHL observations. The trends in the two injury groups also significantly diverged, such that the gap between rates increased with time. The results suggest that the initial observed benefit of MHL has been maintained over the ensuing decades. There is a notable additional safety benefit after 2006 that is associated with an increase in cycling infrastructure spending. This implies that the effect of MHL is ongoing and progress in cycling safety in NSW has and will continue to benefit from focusing on broader issues such as increasing cycling infrastructure.
The impact of compulsory helmet legislation on cyclist head injuries in New South Wales, Australia: A response(2013) Walter, Scott; Olivier, Jake; Churches, Tim; Grzebieta, RaphaelJournal ArticleThis article responds to criticisms made in a rejoinder (Accident Analysis and Prevention 2012, 45: 107–109) questioning the validity of a study on the impact of mandatory helmet legislation (MHL) for cyclists in New South Wales, Australia. We systematically address the criticisms through clarification of our methods, extension of the original analysis and discussion of new evidence on the population-level effects of MHL. Extensions of our analysis confirm the original conclusions that MHL had a beneficial effect on head injury rates over and above background trends and changes in cycling participation. The ongoing debate around MHL draws attention away from important ways in which both safety and participation can be improved through investment in well-connected cycling infrastructure, fostering consideration between road users, and adequate legal protection for vulnerable road users. These are the essential elements for providing a cycling environment that encourages participation, with all its health, economic and environmental benefits, while maximising safety.
(2022) Biswas, Raaj KishoreThesisRear-end crashes are a major part of road injury burden, accounting for one-third of all vehicle-to-vehicle crashes in New South Wales, Australia. Close following or driving with short headways is a key cause, yet the role of driver behaviour in rear-end crash risk is not well researched. The primary aim of this research was to develop a better understanding of rear-end crashes by assessing headways on Australian roads and investigating driver behaviour and performance associated with close following in crash and non-crash scenarios. Two systematic reviews of headway were conducted. First, a review of research on headway identified the need for a consistent and accurate definition of headway, so the thesis puts forward an improved definition. The second review identified the range of external factors that increase the risk of short headway and increase crash risk including speed, task engagement, lead vehicle type, traffic conditions, road characteristics, weather/visibility, drug use, driving fatigue, innovative lane markings, and various warning systems. These factors were then explored in New South Wales data on rear-end casualty and multiple vehicle crashes. The modelling of these associated factors were confirmed as contributing factors in rear-end crashes, congruent with the review of headway. Higher speed, free flowing traffic, volitional task engagement, low cue environments, and collision warning lead to longer headway. Despite lower fatalities, higher odds of injury were observed for rear-end crashes than other crash types. Rear-end crashes were more likely to lead to multiple vehicle crashes, which had a higher chance of fatality than other types of crashes. Finally, naturalistic driving study data was used to investigate headway during normal driving, exploring close following at different speeds and classifying potential risky driving at various headways. In 64 hrs accumulated across 2101 trips, short headways of under 1 s occurred in around 15% of driving. Common manoeuvres to avoid rear-end crashes when close following were changing lanes, or braking, almost always by the following driver. Headway was associated with both driver speed and posted speed limits, decreasing as posted speed limits increased. Over-the-speed-limit driving was observed in all headway scenarios, but especially in higher speed zones. The findings challenge the notion that rear-end crashes are less severe with low injuries. Road users should be made aware of how frequently safe headways are violated and severity of injury outcomes. Driver education, community engagement, application of driver assistance technology consistent with driver behaviour and safety campaigns need to focus on safer speed and headway management to reduce rear-end crash risk.