Matthew Robert Justin Baldock

Self-regulation of driving and older drivers' functional abilities

Abstract This study was designed to identify risk factors for inadequate self-regulation of driving behavior by older drivers. To this end, a sample of 90 adults aged between 60 and 91 completed a questionnaire about their driving behavior, a battery of functional tests, and a structured on-road test. Comparisons were made between the functional tests most strongly related to on-road driving performance and the functional tests most strongly related to self-regulation. Self-reported avoidance of difficult driving situations was used as an index of self-regulation of driving behavior. It was concluded that self-regulation of driving behavior is inadequate among older drivers with poor contrast sensitivity, poor speed of information processing and poor visuospatial ability.

Visual attention as a predictor of on-road driving performance of older drivers

With increasing numbers of older drivers on Australian roads, it is important to determine the functional abilities most closely related to driving ability among older adults. To this end, 90 drivers aged from 60 to 91 completed a battery of psychological, visual, physical and cognitive tests, and a standardised on-road driving test. A computerised test of visual attention, devised specifically for the study, was the best predictor of on-road driving performance. Other abilities that made independent contributions to the prediction of driving performance were contrast sensitivity and visuospatial memory. These functional abilities provided a better prediction of driving performance than chronological age, reinforcing the argument that drivers should only have their driving tested when their functional abilities decline, rather than when they reach a particular age.

An examination of the environmental, driver and vehicle factors associated with the serious and fatal crashes of older rural drivers

Motor vehicle crashes involving rural drivers aged 75 years and over are more than twice as likely to result in a serious or fatal injury as those involving their urban counterparts. The current study examined some of the reasons for this using a database of police-reported crashes (2004-2008) to identify the environmental (lighting, road and weather conditions, road layout, road surface, speed limit), driver (driver error, crash type), and vehicle (vehicle age) factors that are associated with the crashes of older rural drivers. It also determined whether these same factors are associated with an increased likelihood of serious or fatal injury in younger drivers for whom frailty does not contribute to the resulting injury severity. A number of environmental (i.e., undivided, unsealed, curved and inclined roads, and areas with a speed limit of 100km/h or greater) and driver (i.e., collision with a fixed object and rolling over) factors were more frequent in the crashes of older rural drivers and additionally associated with increased injury severity in younger drivers. Moreover, when these environmental factors were entered into a logistic regression model to predict whether older drivers who were involved in crashes did or did not sustain a serious or fatal injury, it was found that each factor independently increased the likelihood of a serious or fatal injury. Changes, such as the provision of divided and sealed roads, greater protection from fixed roadside objects, and reduced speed limits, appear to be indicated in order to improve the safety of the rural driving environment for drivers of all ages. Additionally, older rural drivers should be encouraged to reduce their exposure to these risky circumstances.

The relationship between motorcycle rider behaviour questionnaire scores and crashes for riders in Australia

Motorcycle riders are over-represented in road fatalities in Australia. While riders represent 18% of the road users killed each year, motorcycle registrations constitute only 4.5% of the registered vehicle fleet. The Motorcycle Rider Behaviour Questionnaire (MRBQ) was developed with a view toward understanding behaviours likely to be associated with crash risk. These include behaviours that are either intentional (such as violations of road and speed regulations and stunts) or unintentional (such as errors relating to traffic or control of the motorcycle), as well as protective behaviours related to use of safety equipment. The dual aims of the current study were, first, to determine the appropriate structure of a modified version of the MRBQ for use in a representative sample of riders in Australia and, second, to understand which MRBQ factors are associated with crash involvement. A stratified sampling procedure was undertaken to ensure the socio-economic status of local government area, age and gender of the sample was representative of the broader population of riders in New South Wales, Australia. The sample consisted of 470 riders (males=89%). Exploratory factor analysis revealed a 29-item, five factor structure was suitable on the Australian data encompassing traffic errors, speed violations, protective gear, control errors and stunts. Overall, riders reported relatively safe behaviours, with frequent use of protective gear and infrequent aberrant behaviours. However, even though infrequent, violations of speed and errors related to control of the motorcycle increased the odds of near-crash involvement, whilst stunt behaviours were associated with increased odds of crash involvement. Interventions and countermeasures need to target these specific behaviours.

Examination of the Role of the Combination of Alcohol and Cannabis in South Australian Road Crashes

Objectives: The aim of the present study was to examine the role of cannabis in road crashes in South Australia, with a particular focus on the extent to which crashes involving cannabis also involve alcohol. Methods: Hospital data, police-reported crash data, and the results of forensic tests of blood samples for drugs and alcohol were collected for 1,074 crash participants (drivers or motorcyclists) admitted to hospital. A sample of 135 coroners’ reports was also examined to determine the role of alcohol and cannabis in fatal crashes. Results: The 3 years of linked data for hospital admission cases revealed that alcohol played a greater role in road crashes than other drugs. Approximately 1 in 5 drivers or motorcyclists had a blood alcohol concentration (BAC) above the legal limit of 0.05. Routine testing for cannabis, methamphetamine, and MDMA revealed a drug-positive rate of approximately 1 in 10 of those tested, with over half of these positive to cannabis. More than a third of cannabis cases also involved alcohol. The majority of those who were positive for alcohol had a BAC above 0.15 g/100 mL. BACs were similarly high among drivers positive for both alcohol and cannabis. Conclusions: The findings of the hospital data and the coroners’ reports were consistent with each other in terms of providing confirmation that alcohol is still the drug associated with the greatest level of road trauma on South Australian roads. Furthermore, alcohol was also present in around half of the cannabis cases and, when present, tended to be present at very high levels. The results of this study emphasize that, although drug driving is clearly a problem, the most important form of impaired driving that needs to be the target of enforcement is drink driving. Roadside drug testing is important but should not be conducted in such a way that reduces the deterrent value of random breath testing.

Safe speed limits for a safe system: The relationship between speed limit and fatal crash rate for different crash types

ABSTRACT Objective: The objective of this article is to provide empirical evidence for safe speed limits that will meet the objectives of the Safe System by examining the relationship between speed limit and injury severity for different crash types, using police-reported crash data. Method: Police-reported crashes from 2 Australian jurisdictions were used to calculate a fatal crash rate by speed limit and crash type. Example safe speed limits were defined using threshold risk levels. Results: A positive exponential relationship between speed limit and fatality rate was found. For an example fatality rate threshold of 1 in 100 crashes it was found that safe speed limits are 40 km/h for pedestrian crashes; 50 km/h for head-on crashes; 60 km/h for hit fixed object crashes; 80 km/h for right angle, right turn, and left road/rollover crashes; and 110 km/h or more for rear-end crashes. Conclusions: The positive exponential relationship between speed limit and fatal crash rate is consistent with prior research into speed and crash risk. The results indicate that speed zones of 100 km/h or more only meet the objectives of the Safe System, with regard to fatal crashes, where all crash types except rear-end crashes are exceedingly rare, such as on a high standard restricted access highway with a safe roadside design.

Motorcycle fuel tanks and pelvic fractures: A motorcycle fuel tank syndrome

ABSTRACT Objective: Pelvic injuries are a serious and commonly occurring injury to motorcycle riders involved in crashes, yet there has been limited research investigating the mechanisms involved in these injuries. This study aimed to investigate the mechanisms involved in pelvic injuries to crashed motorcyclists. Method: This study involved in-depth crash investigation and 2 convenience-based data sets were used. These data sets investigated motorcycle crashes in the Sydney, Newcastle, and Adelaide regions. Participants included motorcycle riders who had crashed either on a public road or private property within the study areas. The mechanism of injury and the type of injuries were investigated. Results: The most frequent cause of pelvic injuries in crashed motorcyclists was due to contact with the motorcycle fuel tank during the crash (85%). For riders who had come into contact with the fuel tank, the injury types were able to be grouped into 3 categories based on the complexity of the injury. The complexity of the injury appeared to increase with impact speed but this was a nonsignificant trend. The pelvic injuries that did not occur from contact with the fuel tank in this sample differed in asymmetry of loading and did not commonly involve injury to the bladder. They were commonly one-sided injuries but this differed based on the point of loading; however, a larger sample of these injuries needs to be investigated. Conclusion: Overall improvements in road safety have not been replicated in the amelioration of pelvic injuries in motorcyclists and improvements in the design of crashworthy motorcycle fuel tanks appear to be required.

A robust estimation of the effects of motorcycle autonomous emergency braking (MAEB) based on in-depth crashes in Australia

ABSTRACT Objective: Autonomous emergency braking (AEB) is a safety system that detects imminent forward collisions and reacts by slowing down the host vehicle without any action from the driver. AEB effectiveness in avoiding and mitigating real-world crashes has recently been demonstrated. Research suggests that a translation of AEB to powered 2-wheelers could also be beneficial. Previous studies have estimated the effects of a motorcycle AEB system (MAEB) via computer simulations. Though effects of MAEB were computed for motorcycle crashes derived from in-depth crash investigation, there may be some inaccuracies due to limitations of postcrash investigation (e.g., inaccuracies in preimpact velocity of the motorcycle). Furthermore, ideal MAEB technology was assumed, which may lead to overestimation of the benefits. This study sought to evaluate the sensitivity of the simulations to variations in reconstructed crash cases and the capacity of the MAEB system in order to provide a more robust estimation of MAEB effects. Methods: First, a comprehensive classification of accidents was used to identify scenarios in which MAEB was likely to apply, and representative crash cases from those available for this study were populated for each crash scenario. Second, 100 variant cases were generated by randomly varying a set of simulation parameters with given normal distributions around the baseline values. Variants reflected uncertainties in the original data. Third, the effects of MAEB were estimated in terms of the difference in the impact speed of the host motorcycle with and without the system via computer simulations of each variant case. Simulations were repeated assuming both an idealized and a realistic MAEB system. For each crash case, the results in the baseline case and in the variants were compared. A total of 36 crash cases representing 11 common crash scenarios were selected from 3 Australian in-depth data sets: 12 cases from New South Wales, 13 cases from Victoria, and 11 cases from South Australia. Results: The reduction in impact speed elicited by MAEB in the baseline cases ranged from 2.8 to 10.0 km/h. The baseline cases over- or underestimated the mean impact speed reduction of the variant cases by up to 20%. Constraints imposed by simulating more realistic capabilities for an MAEB system produced a decrease in the estimated impact speed reduction of up to 14% (mean 5%) compared to an idealized system. Conclusions: The small difference between the baseline and variant case results demonstrates that the potential effects of MAEB computed from the cases described in in-depth crash reports are typically a good approximation, despite limitations of postcrash investigation. Furthermore, given that MAEB intervenes very close to the point of impact, limitations of the currently available technologies were not found to have a dramatic influence on the effects of the system.

The prevalence of crash risk factors in a population-based study of motorcycle riders

INTRODUCTION Motorcyclists represent an increasing proportion of road traffic casualties but, while factors associated with crashes are readily identifiable, little is known about the prevalence of those risk factors in the motorcycling population. METHOD A stratified random-sampling frame was used to survey the population of registered motorcycles owners in New South Wales (NSW) when they attended motor registry offices. The postal codes in the State database of registered motorcycle were used to stratify the population into quartiles based on socioeconomic characteristics and to determine sample weights. RESULTS Participants (n=506) represented 47% of eligible riders approached. On average participants were aged 43, rode 7h/week and had 17 years of riding experience. Estimates based on multiple ownership rates suggest motorcycle registration numbers exceed the active riding population by approximately 15%. Less than half rode under 101km/week, 25% rode over 300km/week and just 42% rode every day. More rode frequently for leisure (70%) than for commuting (53%) and over half rarely rode in dark (52%) or wet (67%) conditions. Most wore protective clothing - helmets (100%), jackets (82%), pants (56%), boots (57%) and gloves (73%). Those with traffic infringements (32%) were mostly for driving (25%), not riding (10%) offences. In the past year, 13% had one or more motorcycle crashes including minor spills and 76% one or more near-crash experiences. The youngest riders (15-19) reported the highest rates of exposure in kilometres, hours, frequency of riding and commuting. They also reported lower crash involvement (3%) but more near-crashes (80%). CONCLUSIONS This study provides an account of the prevalence of key risk factors across age groups in a population of active motorcycle riders in NSW. Novice riders were represented in all age groups although most novices were under 40 years. These data can be used to guide the development of targeted countermeasures aimed at improving motorcycling safety for riders of different age groups.

The Functional Correlates of Older Driversʼ On-Road Driving Test Errors

The aim of this study was to determine the functional deficits that predict particular types of driving difficulties among older drivers. A sample of 90 drivers 60 years and older completed a battery of functional (psychological, visual, physical, cognitive, and attentional) tests and a standardized on-road driving test. Driving errors were classified into a set of 7 distinct categories (positioning, gap selection, incorrect speed, observation, speed of approach, mirror, and indicator), and correlation and regression analyses were used to determine the best functional predictors of specific error types. As expected, functional deficits were more strongly related to some error types (eg, positioning errors) than others (eg, failure to indicate). Measures of visual attention were associated with a broad range of error types, and particularly, with errors prompting an intervention from the driving instructor, suggesting that a deficit in visual attention is a key indicator of the likelihood of driving problems. Errors in speed of approach to intersections or before undertaking driving maneuvers appear to be related to problems with vision.