A driving simulator evaluation of potential speed reductions using two innovative designs for signalised urban intersections.

Intersections are typically associated with a higher level of crash risk than other types of facilities on the road network. Standard cross-road intersections are particularly hazardous because by their very design, drivers may travel through at speeds that are incompatible with human biomechanical tolerance should a crash occur. Further, drivers are exposed to dangerous conflict angles, which are likely to result in serious injury. This paper examines the effectiveness of two new intersection designs aimed at restricting potentially dangerous conflict angles while reducing driver speeds through the intersection. These designs, named the "Cut-Through" and the "Squircle", incorporate key features of both signalised intersections and roundabouts. The intersections are controlled by signals similar to a signalised roundabout. Instead of a standard central island, right turning traffic (equivalent to left turns in jurisdictions that drive on the right) cut through the central island, thereby avoiding traffic interlocks and delays that can occur with the traditional signalised roundabout. Across two driving simulator studies, vehicle speed data were collected on approach to and through each of the proposed intersection designs. Performance was benchmarked against equivalent standard signalised cross-road intersections and standard non-signalised roundabouts. Notably, drivers reduced their speeds by approximately 30-40% when negotiating both the Cut-Through and the Squircle compared to the standard signalised intersections. The safety potentials of the two new intersection designs are discussed within the guidelines of the Safe Systems principles.

Calibration of skill and judgment in driving: development of a conceptual framework and the implications for road safety.

Humans often make inflated or erroneous estimates of their own ability or performance. Such errors in calibration can be due to incomplete processing, neglect of available information or due to improper weighing or integration of the information and can impact our decision-making, risk tolerance, and behaviors. In the driving context, these outcomes can have important implications for safety. The current paper discusses the notion of calibration in the context of self-appraisals and self-competence as well as in models of self-regulation in driving. We further develop a conceptual framework for calibration in the driving context borrowing from earlier models of momentary demand regulation, information processing, and lens models for information selection and utilization. Finally, using the model we describe the implications for calibration (or, more specifically, errors in calibration) for our understanding of driver distraction, in-vehicle automation and autonomous vehicles, and the training of novice and inexperienced drivers.

Issues in motorcycle sensory and cognitive conspicuity: the impact of motorcycle low-beam headlights and riding experience on drivers' decisions to turn across the path of a motorcycle.

BACKGROUND: Crashes involving a passenger car and a motorcycle, where the car is turning across the path of the motorcycle, are a major crash type of motorcycle riders. It has been proposed that the incidence of such crashes could be reduced through improvements in motorcycle conspicuity. Operation of low-beam headlights on motorcycles has been discussed as one approach for improving the "sensory conspicuity" of motorcycles during daylight hours, whilst previous experience as a rider may serve to heighten "cognitive conspicuity" through raised awareness of motorcyclists on our roads. METHOD: Twenty-three experienced car drivers with no riding experience ("drivers") and 20 experienced car drivers who were also motorcycle riders ("driver-riders") completed a series of trials in a driving simulator where their task in each trial was to turn ahead of an oncoming vehicle if they felt that they had sufficient room to do so safely. A key manipulation across trials was whether the oncoming vehicle was a motorcycle with headlights on, or a motorcycle with headlights off. Time gap (short, medium, long) was also manipulated. RESULTS: Results indicate that, at time gaps defined in the current study as short, low-beam headlights may confer some benefit in gap acceptance by encouraging drivers to accept fewer gaps ahead of a motorcycle with headlights on than ahead of a motorcycle with headlights off. No statistically significant differences in gap acceptance between the headlight conditions were found at either the medium or long time gaps. Irrespective of time gap, driver-riders were found to adopt a more efficient turn strategy than drivers with no direct riding experience. CONCLUSIONS: Overall, the present research provides support for the use of low-beam headlights and riding experience as tools through which to augment the sensory and cognitive conspicuity of motorcycles, respectively. It is proposed that further research aim to explore directly the precise mechanisms underlying the observed effects.

The effects of using a portable music player on simulated driving performance and task-sharing strategies.

This study examined the effects of performing scrollable music selection tasks using a portable music player (iPod Touch™) on simulated driving performance and task-sharing strategies, as evidenced through eye glance behaviour and secondary task performance. A total of 37 drivers (18-48 yrs) completed the PC-based MUARC Driver Distraction Test (DDT) while performing music selection tasks on an iPod Touch. Drivers' eye glance behaviour was examined using faceLAB eye tracking equipment. Results revealed that performing music search tasks while driving increased the amount of time that drivers spent with their eyes off the roadway and decreased their ability to maintain a constant lane position and time headway from a lead vehicle. There was also evidence, however, that drivers attempted to regulate their behaviour when distracted by decreasing their speed and taking a large number of short glances towards the device. Overall, results suggest that performing music search tasks while driving is problematic and steps to prohibit this activity should be taken.

Effects on driving performance of interacting with an in-vehicle music player: a comparison of three interface layout concepts for information presentation.

Interface design is an important factor in assessing the potential effects on safety of interacting with an in-vehicle information system while driving. In the current study, the layout of information on a visual display was manipulated to explore its effect on driving performance in the context of music selection. The comparative effects of an auditory-verbal (cognitive) task were also explored. The driving performance of 30 participants was assessed under both baseline and dual task conditions using the Lane Change Test. Concurrent completion of the music selection task with driving resulted in significant impairment to lateral driving performance (mean lane deviation and percentage of correct lane changes) relative to the baseline, and significantly greater mean lane deviation relative to the combined driving and the cognitive task condition. The magnitude of these effects on driving performance was independent of layout concept, although significant differences in subjective workload estimates and performance on the music selection task across layout concepts highlights that potential uncertainty regarding design use as conveyed through layout concept could be disadvantageous. The implications of these results for interface design and safety are discussed.