Mark J. King

Dynamic Modulus Testing of Asphalt Concrete in Indirect Tension Mode

This study presents the results from an analytical and experimental study on the dynamic modulus testing of hot-mix asphalt using the indirect tension (IDT) mode. An analytical solution for the dynamic modulus in the IDT mode was developed with the use of linear viscoelasticity. To verify the analytical solution, temperature and frequency sweep tests were conducted on 12 asphalt mixtures commonly used in North Carolina; both axial compression and IDT test methods were used. A modified dynamic modulus test protocol is introduced to reduce the required testing time by using more frequencies and fewer temperatures on the basis of the time-temperature superposition principle. A comparison of results from the axial compression and IDT test methods shows that the dynamic modulus master curves and shift factors derived from the two methods are in good agreement. It also was found that Poissons ratio was a weak function of the loading frequency; its effect on the phase angle master curve is discussed.

Illegal pedestrian crossing at signalised intersections: Incidence and relative risk

Illegal pedestrian behaviour is common and is reported as a factor in many pedestrian crashes. Since walking is being promoted for its health and environmental benefits, minimisation of its associated risks is of interest. The risk associated with illegal road crossing is unclear, and better information would assist in setting a rationale for enforcement and priorities for public education. An observation survey of pedestrian behaviour was conducted at signalised intersections in the Brisbane CBD (Queensland, Australia) on typical workdays, using behavioural categories that were identifiable in police crash reports. The survey confirmed high levels of crossing against the lights, or close enough to the lights that they should legally have been used. Measures of exposure for crossing legally, against the lights, and close to the lights were generated by weighting the observation data. Relative risk ratios were calculated for these categories using crash data from the observation sites and adjacent midblocks. Crossing against the lights and crossing close to the lights both exhibited a crash risk per crossing event approximately eight times that of legal crossing at signalised intersections. The implications of these results for enforcement and education are discussed, along with the limitations of the study.

The impact of changes to the graduated driver licensing program in Queensland, Australia on the experiences of Learner drivers

PURPOSE Graduated driver licensing (GDL) has been introduced in numerous jurisdictions in Australia and internationally in an attempt to ameliorate the significantly greater risk of death and injury for young novice drivers arising from road crashes. The GDL program in Queensland, Australia, was extensively modified in July 2007. This paper reports the driving and licensing experiences of Learner drivers progressing through the current-GDL program, and compares them to the experiences of Learners who progressed through the former-GDL program. METHOD Young drivers (n=1032, 609 females, 423 males) aged 17-19 years (M=17.43, SD=0.67) were recruited as they progressed from a Learner to a Provisional drivers licence. They completed a survey exploring their sociodemographic characteristics, driving and licensing experiences as a Learner. Key measures for a subsample (n=183) of the current-GDL drivers were compared with the former-GDL drivers (n=149) via t-tests and chi-square analyses. RESULTS As expected, Learner drivers progressing through the current-GDL program gained significantly more driving practice than those in the former program, which was more likely to be provided by mothers than in the past. Female Learners in the current-GDL program reported less difficulty obtaining supervision than those in the former program. The number of attempts needed to pass the practical driving assessment did not change, nor did the amount of professional supervision. The current-GDL Learners held their licence for a significantly longer duration than those in the former program, with the majority reporting that their Logbook entries were accurate on the whole. Compared to those in the former program, a significantly smaller proportion of male current-GDL Learners reported being detected for a driving offence whilst the females reported significantly lower crash involvement. Most current-GDL drivers reported undertaking their supervised practice at the end of the Learner period. CONCLUSIONS The enhancements to the GDL program in Queensland appear to have achieved many of their intended results. The current-GDL Learners participating in the study reported obtaining a significantly greater amount of supervised driving experience compared to former-GDL Learners. Encouragingly, the current-GDL Learners did not report any greater difficulty in obtaining supervised driving practice, and there was a decline in the proportion of current-GDL Learners engaging in unsupervised driving. In addition, the majority of Learners do not appear to be attempting to subvert logbook recording requirements, as evidenced by high rates of self-reported logbook accuracy. The results have implications for the development and the evaluation of GDL programs in Australia and around the world.

A further exploration of sensation seeking propensity, reward sensitivity, depression, anxiety, and the risky behaviour of young novice drivers in a structural equation model.

Young novice drivers constitute a major public health concern due to the number of crashes in which they are involved, and the resultant injuries and fatalities. Previous research suggests psychological traits (reward sensitivity, sensation seeking propensity), and psychological states (anxiety, depression) influence their risky behaviour. The relationships between gender, anxiety, depression, reward sensitivity, sensation seeking propensity and risky driving are explored. Participants (390 intermediate drivers, 17-25 years) completed two online surveys at a six month interval. Surveys comprised sociodemographics, Brief Sensation Seeking Scale, Kesslers Psychological Distress Scale, an abridged Sensitivity to Reward Questionnaire, and risky driving behaviour was measured by the Behaviour of Young Novice Drivers Scale. Structural equation modelling revealed anxiety, reward sensitivity and sensation seeking propensity predicted risky driving. Gender was a moderator, with only reward sensitivity predicting risky driving for males. Future interventions which consider the role of rewards, sensation seeking, and mental health may contribute to improved road safety for younger and older road users alike.

The influence of sensitivity to reward and punishment, propensity for sensation seeking, depression, and anxiety on the risky behaviour of novice drivers: A path model

Young novice drivers are significantly more likely to be killed or injured in car crashes than older, experienced drivers. Graduated driver licensing (GDL), which allows the novice to gain driving experience under less-risky circumstances, has resulted in reduced crash incidence; however, the drivers psychological traits are ignored. This paper explores the relationships between gender, age, anxiety, depression, sensitivity to reward and punishment, sensation-seeking propensity, and risky driving. Participants were 761 young drivers aged 17-24 (M=19.00, SD=1.56) with a Provisional (intermediate) drivers licence who completed an online survey comprising socio-demographic questions, the Impulsive Sensation Seeking Scale, Kesslers Psychological Distress Scale, the Sensitivity to Punishment and Sensitivity to Reward Questionnaire, and the Behaviour of Young Novice Drivers Scale. Path analysis revealed depression, reward sensitivity, and sensation-seeking propensity predicted the self-reported risky behaviour of the young novice drivers. Gender was a moderator; and the anxiety level of female drivers also influenced their risky driving. Interventions do not directly consider the role of rewards and sensation seeking, or the young persons mental health. An approach that does take these variables into account may contribute to improved road safety outcomes for both young and older road users.

Mileage, car ownership, experience of punishment avoidance, and the risky driving of young drivers

Objective: Young drivers are at greatest risk of injury or death from a car crash in the first 6 months of independent driving. In Queensland, the graduated driver licensing (GDL) program was extensively modified in July 2007 in order to reduce this risk. Increased mileage and car ownership have been found to play a role in risky driving, offenses, and crashes; however, GDL programs typically do not consider these variables. In addition, young novice drivers’ experiences of punishment avoidance have not previously been examined. This article explores the mileage (duration and distance), car ownership, and punishment avoidance behaviors of young newly licensed intermediate (provisional) drivers and their relationship to risky driving, crashes, and offenses. Methods: Drivers (n = 1032) aged 17 to 19 years recruited from across Queensland for longitudinal research completed survey 1 exploring prelicense and learner experiences and sociodemographic characteristics. survey 2 explored the same variables with a subset of these drivers (n = 341) after they had completed their first 6 months of independent driving. Results: Most young drivers in survey 2 reported owning a vehicle and paying attention to police presence. Drivers who had their own cars reported significantly greater mileage and more risky driving. Novices who drove more kilometers, spent more hours each week driving, or avoided actual and anticipated police presence were more likely to report risky driving. These drivers were also more likely to report being detected by police for a driving-related offense. The media, parents, friends, and other drivers play a pivotal role in informing novices of on-road police enforcement operations. Conclusions: GDL programs should incorporate education for the parent and novice driver regarding the increased risks associated with greater driving, particularly when the novice driver owns a vehicle. Parents should be encouraged to delay exclusive access to a vehicle. Parents should also consider whether their young novices will deliberately avoid police if they are aware of their location. This may reinforce not only the risky behavior but also young novices’ beliefs that their parents condone this behavior.

I drove after drinking alcohol and other risky driving behaviours reported by young novice drivers

BACKGROUND Volitional risky driving behaviours such as drink- and drug-driving (i.e. substance-impaired driving) and speeding contribute to the overrepresentation of young novice drivers in road crash fatalities, and crash risk is greatest during the first year of independent driving in particular. AIMS To explore the: (1) self-reported compliance of drivers with road rules regarding substance-impaired driving and other risky driving behaviours (e.g., speeding, driving while tired), one year after progression from a Learner to a Provisional (intermediate) licence; and (2) interrelationships between substance-impaired driving and other risky driving behaviours (e.g., crashes, offences, and Police avoidance). METHODS Drivers (n=1076; 319 males) aged 18-20 years were surveyed regarding their sociodemographics (age, gender) and self-reported driving behaviours including crashes, offences, Police avoidance, and driving intentions. RESULTS A relatively small proportion of participants reported driving after taking drugs (6.3% of males, 1.3% of females) and drinking alcohol (18.5% of males, 11.8% of females). In comparison, a considerable proportion of participants reported at least occasionally exceeding speed limits (86.7% of novices), and risky behaviours like driving when tired (83.6% of novices). Substance-impaired driving was associated with avoiding Police, speeding, risky driving intentions, and self-reported crashes and offences. Forty-three percent of respondents who drove after taking drugs also reported alcohol-impaired driving. DISCUSSION AND CONCLUSIONS Behaviours of concern include drink driving, speeding, novice driving errors such as misjudging the speed of oncoming vehicles, violations of graduated driver licensing passenger restrictions, driving tired, driving faster if in a bad mood, and active punishment avoidance. Given the interrelationships between the risky driving behaviours, a deeper understanding of influential factors is required to inform targeted and general countermeasure implementation and evaluation during this critical driving period. Notwithstanding this, a combination of enforcement, education, and engineering efforts appear necessary to improve the road safety of the young novice driver, and for the drink-driving young novice driver in particular.

Young, inexperienced, and on the road

The graduated driver licensing (GDL) program in Queensland, Australia, was considerably enhanced in July 2007. This paper explores the compliance of young learner and provisional (intermediate) drivers with current GDL requirements and general road rules. Unsupervised driving, learner logbook accuracy, and experiences of punishment avoidance were explored as was speeding as a provisional driver. Participants (609 females, 423 males; M = 17.43 years) self-reported their sociodemographic characteristics, driving behaviors, and licensing experiences as learners. Six months later, a subset of participants (238 females, 105 males) completed another survey that explored their provisional behaviors and experiences. Although the majority of participants reported compliance with both the GDL requirements and general road rules, such as stopping at red lights on their learner license, a considerable proportion reported speeding. Furthermore, they reported becoming less compliant during the provisional phase, particularly with speed limits. Self-reported speeding was predicted by the following variables: younger age at licensure, being in a relationship, driving unsupervised, submitting inaccurate learner logbooks, and speeding as a learner. Enforcement and education countermeasures should focus on curtailing noncompliance, targeting speeding in particular. Novice drivers should be encouraged to comply with all road rules, including speed limits, and safe driving behaviors should be developed and reinforced during the learner and early provisional periods. Novice drivers have been found to model their parents’ driving, and parents are pivotal in regulating novice driving. It is vital that young novice drivers and parents alike be encouraged to comply with all road rules, including GDL requirements.

Random breath testing in Queensland and Western Australia: examination of how the random breath testing rate influences alcohol related traffic crash rates

In this paper we explore the relationship between monthly random breath testing (RBT) rates (per 1000 licensed drivers) and alcohol-related traffic crash (ARTC) rates over time, across two Australian states: Queensland and Western Australia. We analyse the RBT, ARTC and licensed driver rates across 12 years; however, due to administrative restrictions, we model ARTC rates against RBT rates for the period July 2004 to June 2009. The Queensland data reveals that the monthly ARTC rate is almost flat over the five year period. Based on the results of the analysis, an average of 5.5 ARTCs per 100,000 licensed drivers are observed across the study period. For the same period, the monthly rate of RBTs per 1000 licensed drivers is observed to be decreasing across the study with the results of the analysis revealing no significant variations in the data. The comparison between Western Australia and Queensland shows that Queenslands ARTC monthly percent change (MPC) is 0.014 compared to the MPC of 0.47 for Western Australia. While Queensland maintains a relatively flat ARTC rate, the ARTC rate in Western Australia is increasing. Our analysis reveals an inverse relationship between ARTC RBT rates, that for every 10% increase in the percentage of RBTs to licensed driver there is a 0.15 decrease in the rate of ARTCs per 100,000 licenced drivers. Moreover, in Western Australia, if the 2011 ratio of 1:2 (RBTs to annual number of licensed drivers) were to double to a ratio of 1:1, we estimate the number of monthly ARTCs would reduce by approximately 15. Based on these findings we believe that as the number of RBTs conducted increases the number of drivers willing to risk being detected for drinking driving decreases, because the perceived risk of being detected is considered greater. This is turn results in the number of ARTCs diminishing. The results of this study provide an important evidence base for policy decisions for RBT operations.

Required hours of practice for learner drivers: a comparison between two Australian jurisdictions

PROBLEM This study considers whether requiring learner drivers to complete a set number of hours while on a learner license affects the amount of hours of supervised practice that they undertake. It compares the amount of practice that learners in Queensland and New South Wales report undertaking. At the time the study was conducted, learner drivers in New South Wales were required to complete 50 hours of supervised practice while those from Queensland were not. METHOD Participants were approached outside driver licensing centers after they had just completed their practical driving test to obtain their provisional (intermediate) license. Those agreeing to participate were interviewed over the phone later and asked a range of questions to obtain information including socio-demographic details and amount of supervised practice completed. RESULTS There was a significant difference in the amount of practice that learners reported undertaking. Participants from New South Wales reported completing a significantly greater amount of practice (M=73.3 hours, sd=29.12 hours) on their learner license than those from Queensland (M=64.1 hours, sd=51.05 hours). However, the distribution of hours of practice among the Queensland participants was bimodal in nature. Participants from Queensland reported either completing much less or much more practice than the New South Wales average. SUMMARY While it appears that the requirement that learner drivers complete a set number of hours may increase the average amount of hours of practice obtained, it may also serve to discourage drivers from obtaining additional practice, over and above the required hours. IMPACT ON INDUSTRY The results of this study suggest that the implications of requiring learner drivers to complete a set number of hours of supervised practice are complex. In some cases, policy makers may inadvertently limit the amount of hours learners obtain to the mandated amount rather than encouraging them to obtain as much practice as possible.