Loading Drivers to Their Limit: The Effect of Increasing Secondary Task On Driving

This paper outlines the results of a number of studies that were designed to create a series of suitable “secondary tasks” that would act as appropriate surrogate in-vehicle information systems (s-IVIS). In particular, an attempt was made to design tasks that would allow a step-by-step increase in visual or cognitive load. Following a brief introduction to the development of each s-IVIS, the paper will present results from a study which examined the effect of completing an auditory s-IVIS on a simulated driving task

A Driving Simulator Study to Examine the Role of Vehicle Acoustics on Drivers’ Speed Perception

In recent years, there has been a desire by vehicle manufacturers to reduce the in-cab noise of vehicles, in order to improve driver comfort and enhance the enjoyment of in-vehicle entertainment systems. This reduction of incab noise is accompanied by policy initiatives to reduce transport related noise by implementing low noise road surfaces. However, it is not known how such reductions in the availability of auditory cues affect drivers’ ability to judge speed, and there is a danger that drivers will increase their speed, to compensate for the absence of auditory cues. In this study, drivers were required to maintain speed at 30 and 70 mph, in the absence of a speedometer, with and without accompanying vehicle noise. Results showed that drivers’ ability to maintain the correct speed profile was much more variable in the absence of accompanying vehicle noise and this variation was found to be higher when drivers were asked to travel at higher speeds of 70 mph. Drivers were also found to travel faster than the required speed in the absence of vehicle noise, although their ability to maintain speed was generally worse at 70 mph, even in the presence of auditory cues

Shut up I\u27m Driving! Is Talking to an Inconsiderate Passenger the Same as Talking on a Mobile Telephone?

The objective of this study was to compare driving performance whilst talking on a hands-free mobile (cellular) telephone with performance during conversations with “considerate” and “inconsiderate” passengers. Using the Leeds Advanced Driving Simulator, participants were asked to drive through a road containing four driving scenarios: (1) car following along a straight road section, (2) car following along a curved section of road, (3) a braking event, and (4) a coherence event. A working memory digit recall and sentence verification task were used to simulate conversation in three conversation conditions: (1) “considerate passenger,” where the experimenter asked drivers to responsd to the working memory task before and after a driving event, (2) “inconsiderate passenger,” where the experimenter asked drivers to responsd to the working memory task throughout a driving event, and “3) “mobile phone task,” which involved digital presentation of the working memory task via a mobile telephone throughout the driving events. A silent condition was also used as control. The effect of the three conversation conditions on driving performance was the same during the simple car following scenarios. However, talking to an “inconsiderate” passenger was found to be as disrupting as a mobile phone conversation, and different from conversing with a considerate passenger, during the braking and coherence conditions. Therefore, the high workload imposed by conversation was only detrimental during the more difficult driving conditions, when demand for central attentional resources from both tasks was at its highest

Multisensory Signal Detection: How Does Driving and IVIS Management Affect Performance?

Signal detection was used as a ‘tertiary’ task to assess drivers’ ‘spare processing capacity’ during the performance of two in-vehicle information systems (IVIS). The main aims of the study were: a) to establish if performance on signal detection can be used to assess IVIS safety during driving and b) to determine whether signal modality is important for this assessment. Participants performed each IVIS (Phone or Count) during a driving simulation experiment. In addition to performing the driving and IVIS, participants were required to complete three detection tasks (DT): (i) a visual DT (ii) an auditory DT, and (iii) a tactile DT. Average reaction time to the DTs was found to increase by around 200ms when performed with the IVIS tasks. It can be argued that any significant increase in reaction time to the DTs is a good indicator of drivers’ reduced hazard perception/situation awareness, which might occur as a result of using in-car systems. No significant difference in performance was found between the various DTs, suggesting that performance relies on central attentional resources, and is not modality-specific. This affords some flexibility for assessing the safety of IVIS in different driving environments. For instance, an auditory DT might be used in field studies on a sunny day when bright light hinders detection of LEDs used in a visual version of the task. Similarly, the tactile version of the task might be useful for testing IVIS in a noisy driving environment

Can Low Cost Road Engineering Measures Combat Driver Fatigue? A Driving Simulator Investigation

Driver fatigue is a major cause of road accidents, accounting for over 20% of serious accidents on motorways and monotonous roads in the U.K. This study investigated the potential for low-cost, road-based, engineering measures to act as alerting features in an otherwise monotonous driving environment and hence combat fatigue. Thirty-three drivers took part in the driving simulator study. There was some evidence of an alerting effect provided to drivers by all three of the treatments tested: chevron road-surface markings, transversecarriageway rumble strips and variable message signs. However, the alerting effect did appear to be relatively weak and potentially quite short-lived. Nevertheless, there may well be potential for any of the novel alerts to be deployed in the field in a known fatigue-related accident area

The Design of Haptic Gas Pedal Feedback to Support Eco-Driving

Previous literature suggests that haptic gas pedals can assist the driver in search of maximum fuel economy. This study investigated three haptic pedal designs, each with high and low intensities of feedback, in a rapid prototyping, paired comparison design. Twenty drivers took part, experiencing the systems in a high-fidelity driving simulator. Results suggested that drivers were best guided towards an “idealized” (most fuel efficient) gas pedal position by force feedback (where a driver feels a step change in gas pedal force) as opposed to stiffness feedback (where a driver feels a changing gas pedal firmness). In either case, high levels of force/stiffness feedback were preferred. Objective performance measures mirrored the subjective results. Whilst the short-term nature (brief system exposure) of this study led to difficulties in drawing longer-term conclusions, it would appear that force feedback haptics are better suited than stiffness feedback to augment an effective driver interface supporting “green” driving

Fully-Automated Driving: The Road to Future Vehicles

The study investigated the impact of fully-automated vehicle control on driver behaviour, physiology and the uptake of secondary tasks in varying traffic conditions. Previous studies have indicated the potential ironies of such automation on fatigue, stress and situational awareness, but have also suggested potential benefits through enhanced safety, more efficient traffic flows and reduced driver workload. The research was undertaken in a high-fidelity driving simulator that allowed drivers to see, feel and hear the impact of the automated control. Independent factors of Drive Type (manual control, fully-automated) and Traffic Density (light, heavy) were manipulated in a repeated-measures experimental design. 49 drivers participated. Drivers experiencing full vehicle automation tended to refrain from behaviours, such as overtaking, that required them to temporarily retake manual control, accepting the resulting increase in journey time. Automation improved safety margins in car following, but this benefit was restricted only to conditions of light surrounding traffic. Automation also reduced heart rate and increased driver fatigue, the latter being mitigated somewhat by high traffic density. Furthermore, drivers became more heavily involved with in-vehicle entertainment than they were in manual driving, affording less visual attention to the road ahead. Drivers do appear happy to forgo their supervisory responsibilities in preference of a more entertaining automated drive. However, these responsibilities are taken more seriously as supervisory demand increases

Towards game theoretic AV controllers: measuring pedestrian behaviour in Virtual Reality

Understanding pedestrian interaction is of great importance for autonomous vehicles (AVs). The present study investigates pedestrian behaviour during crossing scenarios with an autonomous vehicle using Virtual Reality. The self-driving car is driven by a game theoretic controller which adapts its driving style to pedestrian crossing behaviour. We found that subjects value collision avoidance about 8 times more than saving 0.02 seconds. A previous lab study found time saving to be more important than collision avoidance in a highly unrealistic board game style version of the game. The present result suggests that the VR simulation reproduces real world road-crossings better than the lab study and provides a reliable test-bed for the development of game theoretic models for AVs

How Do Drivers Behave in a Highly Automated Car?

This paper outlines the results of a driving simulator study conducted for the European CityMobil project, which was designed to investigate the effect of a highly automated driving scenario on driver behaviour. Drivers’ response to a number of ‘critical’ scenarios was compared in manual driving with that in automated driving. Drivers were in full control of the vehicle and its manoeuvres in the manual driving condition, whilst control of the vehicle was transferred to an ‘automated system’ in the automated driving condition. Automated driving involved the engagement of lateral and longitudinal controllers, which kept the vehicle in the centre of the lane and at a speed of 40 mph, respectively. Drivers were required to regain control of the driving task if the automated system was unable to handle a critical situation. An auditory alarm forewarned drivers of an imminent collision in such critical situations. Drivers’ response to all critical events was found to be much later in the automated driving condition, compared to manual driving. This is thought to be because drivers’ situation awareness was reduced during automated driving, with response only produced after drivers heard the alarm. Alternatively, drivers may have relied too heavily on the system, waiting for the auditory alarm before responding in a critical situation. These results suggest that action must be taken when implementing fully automated driving to ensure that the driver is kept in the loop at all times and is able to respond in time and appropriately during critical situations

Human factors implications of vehicle automation: Current understanding and future directions

Advances in vehicle-based technology are currently progressing at an ever- increasing rate and innovations in this area are no longer restricted to Original Equipment Manufacturers or the automotive industry, with service providers such as Google and a number of research institutes in Europe and North America also offering possibilities for new approaches to mobility (see http://www.driverless-future.com/?page_id=155). The race to test the first fleet of such vehicles on public roads is currently underway, with Volvo Cars announcing the start of its Drive Me project by 2017 (Volvo Cars, 2013) and the UK Government recently encouraging cities to engage in demonstrating trials of such vehicles on public roads from January 2015 (BBC, 2014). However, the homogeneous global implementation of fully autonomous vehicles is unlikely in the near to distant future