Some implications from the in-depth study and simulation modelling of road departure crashes on bends on rural roads

Previous work by the authors has questioned the philosophy of reliance on clearzones, rather than barriers, for rural road safety. In-depth investigation and simulation modelling of a sample of real world crashes has highlighted that even if clearzones of 10 metres could be achieved throughout the rural road network, there are certain vehicle control mechanisms that are not adequately accommodated when a vehicle departs the road. This paper extends this work based on 64 investigated crashes on rural roads at bends and nine computer simulations of these crashes. Bends are over-represented in rural crashes yet the provision of clearzones tends to mimic that of straight sections of road in practice. The study summarizes the characteristics of the investigated crashes in the context of departures and vehicle control mechanisms and discusses the implications of the findings on the provision of safety features on rural roads. The provision of roadside barriers is also discussed including location relative to the bend and offset from the edge of the traffic lane.Doecke, S., & Woolley, J

Further investigation into the effective use of clear zones and barriers in a safe system's context on rural roads

This paper extends an exploratory study that assessed the traditional implementation of clear zones and compared their effectiveness at reducing injury severity with that provided by protective barriers. The results presented in this paper support the findings of the original study in challenging the conventional approach of pursuing wide clear zones. A sample of 132 crashes from the Centre for Automotive Safety Research’s in-depth crash investigations were analysed to determine the typical dynamics of vehicles in single vehicle run off road crashes. The mean departure angle of vehicles that drifted off the road without losing control was only 7.3 degrees while for vehicles that were out of control it was 17.6 degrees. Only three of the 18 vehicles in the cases where no fixed object was struck did not travel beyond a traditional nine metre clear zone. Simulations were performed for 15 of the cases. The cases chosen for simulation represented typical vehicle departure dynamics. Each case was simulated with the driver attempting to recover by steering input and then again with the driver employing emergency braking half a second after departing the road. These simulations revealed that it would rarely be feasible to provide a clear zone wide enough to accommodate a vehicle that has left the road out of control. Clear zones can accommodate vehicles that simply drift off the road without losing control. The simulations were also used to assess the appropriateness of barrier protection. Barrier protection has the potential to meet the requirements of a safe system. Ideally the barrier would be placed as close to the edge of road as practical to reduce the angle at which it may be struck.S. D. Doecke and J. E. Woolle

Post impact travel and secondary impacts following urban intersection collisions

This paper describes the path of vehicles following a collision with another vehicle at a metropolitan intersection. The aim was to provide guidance to transport authorities on roadside design at intersections to protect vehicles from secondary collisions with roadside objects. Detailed information from in-depth investigations of 78 intersection crashes were analysed. Crashes at signalised and unsignalised intersections were analysed separately. Secondary collisions with roadside objects were identified with 16 signalised and 16 unsignalised intersection cases. Nine of these 32 collisions were more severe than the initial vehicle-to-vehicle collision, three at signalised intersections and six at unsignalised intersections. Of the 78 intersection crashes, more than half of the vehicles came to rest within 10 metres of the impact point. More than a quarter travelled 15 metres or further and approximately 10% travelled further than 27 metres. It was found that 28 of the 70 crash involved vehicles at signalised intersections encroached into the designated pedestrian crossing areas. It was also found that 10 of those vehicles departed the roadway. The study has indicated the most likely locations that vehicles will traverse following collisions at urban intersections. This information can be used by road designers to make decisions in relation to the protection or removal of roadside objects in the vicinity of intersections.Doecke, S., & Woolley, J

Post impact trajectory of vehicles at rural intersections

This report describes the path of vehicles following a collision with another vehicle at a rural intersection. Detailed information from in-depth investigations of 70 intersection crashes was analysed. Rear end crashes at intersections were excluded as were collisions involving a motorcycle. The vehicle which had right of way most commonly had an impact speed of between 80 and 99 km/h and the impact point was on the front of the vehicle. The vehicle which was required to give way most commonly had an impact speed of between zero and 20 km/h and was struck between the front of the vehicle and the B-pillar. After the vehicle to vehicle impact half the vehicles travelled more than 18 metres, 20% more than 34 metres and 10% more than 50 metres from the centre of the intersection. The most common direction of the vehicle following the initial impact was found to be between 15 and 29.9 degrees, where the original direction of travel of the through vehicle is at zero degrees. Intersection geometry, speed zone, impact point and mass ratio influence the nature of the post impact trajectory of the vehicles involved. As the results show a high number of vehicles travel a large distance at a shallow angle following an intersection collision, extending crash barriers on the through road (the road with right of way) right up to the intersection may have some benefit. Clear zones surrounding the intersection are also advisable and have an added benefit of increasing sight distance. Hazards can be assessed for removal or relocation by applying the results of this study.SD Doecke, JRR Mackenzie, JE Woolle

Advisory Intelligent Speed Adaptation for government fleets

This project sought to determine the likely crash savings if state government fleets in Australia were fitted with advisory Intelligent Speed Adaptation (ISA). The cost effectiveness of such a fitment was assessed considering if the ISA device is kept within the government fleet (scenario 1) or if it is left in the government vehicle when it is sold (scenario 2). Data from the fleet vehicles involved in the recent NSW ISA was used. The reduction in crash risk was calculated by applying Kloeden’s risk curves for travel speed to the “before” speed profile and the “ISA active” speed profile found in the trial. The reduction in risk was then estimated in terms of the difference in the total crash risk produced by these speed profiles. ISA was found to have the potential to reduce casualty crashes in government fleets by 20%. It was estimated that this would eliminate 171 casualty crashes involving state government vehicles per year and save $31.6 million in crash costs per year. Scenario 1 was more cost effective than scenario 2, although the wider benefit to the community produced by scenario 2 was not taken into account. Of the four ISA devices considered the navaid device that included ISA functionality was found to be the most cost effective.SD Doecke, RWG Anderson, JE Woolle

The potential of autonomous emergency braking systems to mitigate passenger vehicle crashes

This paper details part of a research program conducted to examine the potential effect of autonomous emergency braking (AEB) systems on common crash types that involve a frontal collision. To accomplish this, simulations were conducted of 103 real world crashes. AEB system models with differing specifications were applied to these simulations to determine the change in impact speed that various AEB interventions could produce. It was found that AEB systems have the potential to reduce the impact speed, and hence the severity, in pedestrian crashes, right turn crashes, head on crashes, rear end crashes and hit fixed object crashes. The greatest potential reductions were for pedestrian crashes, head on crashes and rear end crashes. The variations in system specification demonstrate the advantages of a longer time-to-collision and higher autonomous deceleration. A system that has less potential to generate false alarms than the other systems was considered and demonstrated potential for reducing the impact speed in pedestrian, head on, rear end and hit fixed object crashes.S.D. Doecke, R.W.G. Anderson, J.R.R. Mackenzie and G. Pont

A conformational variant of p53 (U-p53AZ) as blood-based biomarker for the prediction of the onset of symptomatic Alzheimer\u27s disease

BACKGROUND: Ongoing research seeks to identify blood-based biomarkers able to predict onset and progression of Alzheimer\u27s disease (AD). OBJECTIVE: The unfolded conformational variant of p53 (U-p53AZ), previously observed in AD individuals, was evaluated in plasma samples from individuals participating in the Australian Imaging, Biomarkers and Lifestyle (AIBL) cohort for diagnostic and prognostic assessment, validated on a neuropsychological-based diagnosis, over the course of six years. DESIGN: Retrospective Longitudinal Prognostic biomarker study. SETTING: Single-center study based on the AIBL cohort. PARTICIPANTS: 482 participants of the AIBL cohort, aged 60-85 years, without uncontrolled diabetes, vascular disease, severe depression or psychiatric illnesses. MEASUREMENTS: The AlzoSure® Predict test, consisting of immunoprecipitation (IP) followed by liquid chromatography (LC) tandem mass spectrometry (MS/MS), was performed to quantify the AZ 284® peptide as readout of U-p53AZ and compared with an independent neuropsychological diagnosis. The amyloid load via amyloid β-positron emission tomography (Aβ-PET) and supporting clinical information were included where possible. RESULTS: U-p53AZ diagnostic and prognostic performance was assessed in both time-independent and time-dependent (36, 72 and 90 months following initial sampling) analyses. Prognostic performance of Aβ-PET and survival analyses with different risk factors (gender, Aβ-PET and APOE ε4 allele status) were also performed. U-p53AZ differentiated neuropsychologically graded AD from non-AD samples, and its detection at intermediate/high levels precisely identified present and future symptomatic AD. In both time-independent and time-dependent prognostic analyses U-p53AZ achieved area under the curve (AUC) \u3e98%, significantly higher than Aβ-PET AUCs (between 84% and 93%, P respectively \u3c0.0001 and \u3c0.001). As single factor, U-p53AZ could clearly determine the risk of AD neuropsychological diagnosis over time (low versus intermediate/high U-p53AZ hazard ratio=2.99). Proportional hazards regression analysis identified U-p53AZ levels as a major independent predictor of AD onset. CONCLUSIONS: These findings support use of U-p53AZ as blood-based biomarker predicting whether individuals would reach neuropsychologically-defined AD within six years prior to AD diagnosis. Integration of U-p53AZ in screening processes could support refined participant stratification for interventional studies

The influence of baseline sleep on exercise-induced cognitive change in cognitively unimpaired older adults: A randomised clinical trial

Objectives: Observational studies consistently demonstrate that physical activity is associated with elevated cognitive function, however, there remains significant heterogeneity in cognitive outcomes from randomized exercise interventions. Individual variation in sleep behaviours may be a source of variability in the effectiveness of exercise-induced cognitive change, however this has not yet been investigated. The current study aimed to (1) investigate the influence of a 6-month exercise intervention on sleep, assessed pre- and post-intervention and, (2) investigate whether baseline sleep measures moderate exercise-induced cognitive changes. Methods: We utilised data from the Intense Physical Activity and Cognition (IPAC) study (n = 89), a 6-month moderate intensity and high intensity exercise intervention, in cognitively unimpaired community-dwelling older adults aged 60–80 (68.76 ± 5.32). Exercise was supervised and completed on a stationary exercise bicycle, and cognitive function was measured using a comprehensive neuropsychological battery administered pre- and post-intervention. Sleep was measured using the Pittsburgh sleep quality index. There was no effect of the exercise intervention on any sleep outcomes from pre- to post-intervention. Results: There was a significant moderating effect of baseline sleep efficiency on both episodic memory and global cognition within the moderate intensity exercise group, such that those with poorer sleep efficiency at baseline showed greater exercise-induced improvements in episodic memory. Conclusions: These results suggest that those with poorer sleep may have the greatest exercise-induced cognitive benefits and that baseline sleep behaviours may be an important source of heterogeneity in previous exercise interventions targeting cognitive outcomes