A. Hamish Jamson

Highly Automated Driving, Secondary Task Performance, and Driver State

Objective: A driving simulator study compared the effect of changes in workload on performance in manual and highly automated driving. Changes in driver state were also observed by examining variations in blink patterns. Background: With the addition of a greater number of advanced driver assistance systems in vehicles, the driver’s role is likely to alter in the future from an operator in manual driving to a supervisor of highly automated cars. Understanding the implications of such advancements on drivers and road safety is important. Method: A total of 50 participants were recruited for this study and drove the simulator in both manual and highly automated mode. As well as comparing the effect of adjustments in driving-related workload on performance, the effect of a secondary Twenty Questions Task was also investigated. Results: In the absence of the secondary task, drivers’ response to critical incidents was similar in manual and highly automated driving conditions. The worst performance was observed when drivers were required to regain control of driving in the automated mode while distracted by the secondary task. Blink frequency patterns were more consistent for manual than automated driving but were generally suppressed during conditions of high workload. Conclusion: Highly automated driving did not have a deleterious effect on driver performance, when attention was not diverted to the distracting secondary task. Application: As the number of systems implemented in cars increases, an understanding of the implications of such automation on drivers’ situation awareness, workload, and ability to remain engaged with the driving task is important.

Control Task Substitution in Semiautomated Driving: Does It Matter What Aspects Are Automated?

Objective: The study was designed to show how driver attention to the road scene and engagement of a choice of secondary tasks are affected by the level of automation provided to assist or take over the basic task of vehicle control. It was also designed to investigate the difference between support in longitudinal control and support in lateral control. Background: There is comparatively little literature on the implications of automation for drivers’ engagement in the driving task and for their willingness to engage in non-driving-related activities. Method: A study was carried out on a high-level driving simulator in which drivers experienced three levels of automation: manual driving, semiautomated driving with either longitudinal or lateral control provided, and highly automated driving with both longitudinal and lateral control provided. Drivers were free to pay attention to the roadway and traffic or to engage in a range of entertainment and grooming tasks. Results: Engagement in the nondriving tasks increased from manual to semiautomated driving and increased further with highly automated driving. There were substantial differences in attention to the road and traffic between the two types of semiautomated driving. Conclusion: The literature on automation and the various task analyses of driving do not currently help to explain the effects that were found. Lateral support and longitudinal support may be the same in terms of levels of automation but appear to be regarded rather differently by drivers.

Driving simulators for robust comparisons: A case study evaluating road safety engineering treatments

Road authorities considering the implementation of speed management interventions should have access to the results of scientifically robust evaluations on which to base their decisions. However, studies that evaluate a diverse range of interventions with comparable metrics are rare, with most focussing on one type, for example, types of signage, perceptual countermeasures or physical traffic calming. This paper describes a driving simulator study designed to overcome these constraints. Twenty diverse speed-reducing treatments were developed and tested in urban and rural road environments. Forty participants encountered all the treatments allowing a comparison to be made with their driving behaviour when the treatment was not present. A number of speed parameters were developed to encapsulate the range of effects of the treatments. The results suggest that whilst straight sections of road are difficult to treat, speed reductions can be obtained by increasing risk perception. In contrast, alerting treatments had more effect at junctions, particularly in an urban environment; drivers approaching curves demonstrated improved speed adaptation if the curve radius was highlighted (either implicitly or explicitly). The study highlights how driving simulators can be used to overcome methodological constraints encountered in real-world evaluations of this type.

Driving Simulators as Research Tools in Traffic Psychology

Publisher Summary Driving simulators are now a major tool, arguably the major tool, for research on driver performance and behavior. Using two major journals—Transportation Research Part F and Human Factors—as the benchmark, it can be seen that studies based on simulator research constitute a major proportion of the published papers in the driving domain. Simulators provide the opportunity to investigate driving under controlled conditions in a manner that is unparalleled by the alternatives. Real-world studies lack the equivalent control element, whereas test tracks offer a very depleted and inflexible driving environment. Simulator capability, particularly in terms of the graphics performance of PC-based systems, has grown very fast in recent years, and the advent of small-scale and relatively low-cost motion systems means that it may soon become a standard for a midrange simulator to be equipped with six degrees of freedom of motion. The number of research simulators worldwide continues to increase, and simulator studies constitute an increasing proportion of the research literature on driving performance and behavior. Simulators may not be total replicates of the real world, and indeed they cannot be. But they offer the researcher of driver behavior an advantage that real-world studies cannot match: the ability to control experimental conditions and create prescripted scenarios.

Driver response to controllable failures of fixed and variable gain steering

Active Front Steer (AFS) is a variable gain steering system that can be a useful driver aid: less wheel input is required to steer at low speeds than a more traditional fixed-gain (FG) system. However, should an AFS system fail, the sudden change in steering gain is potentially hazardous. Using a fully-immersive simulator, forty drivers participated in this single-blind study which compared driver response to both operational and failed AFS compared to a FG system with both functional and failed power steering. At low speeds, whilst negotiating an intersection, drivers rated AFS higher than FG for ease of steering. There were also trends suggesting that AFS failure was easier for drivers to control than the loss of power-assist to the FG system. At high speeds, AFS also showed advantages: drivers rated AFS higher and demonstrated fewer steering micro-corrections, intimating that maintaining control of the vehicle was less demanding with AFS.