Editorial

Recently, considerable technological progress has been made in the field of AutomatedDriver Assistance Systems (ADAS). Electronic devices inform or support the driver inaccident-prone driving situations, in order to improve the critical task of driving a motorvehicle. Potentially, ADAS offers important advantages for road transportation: increasedcontrol with respect to the speed and the position of vehicles on the road is important forestablishing homogeneous traffic flows and reducing the number of accidents. As suchADAS is assumed to have a positive impact on the use of road infrastructure and trafficsafety (Boussuge & Valade, 1994). Moreover, this could lead to a reduction of energy useand polluting gas emissions (Barth, 1995; Michaelian & Browand, 2000). As soon as parts ofor the whole driving task are supported and/or executed automatically by ADAS, vehicledriving could become more comfortable and more convenient as compared to today’s manualdriving (Stevens, 1997; Hoedemaeker, 1999). These expectations imply a high potential inindividual and societal advantages. In various countries, therefore, transport policy makers areincreasingly interested in the automation of vehicle driving tasks. However, current policydevelopment regarding ADAS is highly complicated by, among others, much uncertainty onfuture ADAS development and implementation in terms of whether ADAS implementationwill contribute to or conflict with transport policy goals, and the basic societal conditionsrequired for ADAS implementation (Marchau, 2000

The consequences of an increase in heavy goods vehicles for passenger car drivers' mental workload and behaviour:A simulator study

The effects of an increase in Heavy Goods Vehicles (HGVs) on merging behaviour and on mental workload of motorists during filtering in and out of traffic were studied. Participants drove in a driving simulator in a total of 12 conditions; twice in each of two weather conditions and in three traffic conditions. The weather conditions were clear weather and foggy weather. The traffic conditions were without HGVs (i.e. only private cars), the current mix of HGVs and private cars, and a condition with a 70% increase of HGVs leading to an HGV column in the slow lane. The focus of the study was on assessing effects on behaviour and mental workload during filtering into traffic, and during exiting from the motorway. During the experiment driving performance was registered, behaviour was observed, self reports were collected, and the participant's heart rate was recorded. The results showed that directly after filtering into traffic the variation in driving speed increased and the minimum time headway decreased with an increase in the proportion of HGVs. Joining motorway traffic was considered to involve greater effort and risk in the condition with a column of HGVs. The effects of the conditions on heart rate are less clear, although the moment when the participants joined the traffic is clearly visible. The effects of weather conditions were limited, drivers adapting their driving behaviour in adverse weather by reducing speed. To exit the motorway is not a difficult manoeuvre. For that reason the lane change from the left hand to the fight hand lane that preceded the exit was analysed. Although increased mental effort was reported and the lane change was visible in the heart rate record, no critical changes as a result of increase in proportion of HGVs were found for this manoeuvre. However, in the condition with a column of HGVs, the exit that had to be taken was most frequently missed as HGVs obstructed the view of the exit signs. It is concluded that an increase in HGVs will make merging into traffic more mentally demanding and will decrease safety margins

Effects of listening to music, and of using a handheld and handsfree telephone on cycling behaviour

The effects of listening to music on cycling behaviour were evaluated. Twenty-five participants completed a track on a bicycle while listening to music with two standard earbuds, with one earbud, and with two in-earbuds. Conditions with high tempo music and loud volume were also included in the experiment, as were two mobile phone conditions, one in which participants operated the phone hand held and one handsfree condition. Cycle speed was not affected by listening to music, but was reduced in the telephone conditions. In general the response to auditory signals worsened when participants listened to music, in particular when listening with in-earbuds loud auditory stop signals were missed in 68% of the cases. However, when listening with only one standard earbud performance was not affected. In the conditions when participants listened to high volume and to high tempo music, the auditory stop signal was also heard in significantly fewer cases. Completing a task on the mobile phone, using both handheld and handsfree sets, resulted in increased response time to an auditory stop signal and also reduced overall auditory perception. Furthermore, handsfree operation only had minor advantages opposed to hand held operation, with only response time to an auditory stop signal resulting in faster performance. This is likely to be related to the fact that both hands could be used for braking. It is concluded that listening to music worsens auditory perception, in particular if in-earbuds are used. Furthermore, both handheld and handsfree operation of mobile phones has a negative effect on perception, potentially forming a threat to cyclist traffic safety. (C) 2011 Elsevier Ltd. All rights reserved

That’s close enough:A threshold effect of time headway on the experience of risk, task diffculty, effort, and comfort

Subjective impressions of task difficulty, risk, effort, and comfort are key variables of several theories of driver behaviour. A point of difference between many of these theories is not only the importance of these variables, but also whether they are continuously present and monitored or only experienced by individuals at certain critical points in the driving task. Both a threshold relationship and evidence of constant monitoring of risk and task difficulty have been found for speed choice. In light of these conflicting findings this study seeks to examine a different part of the driving task, the choice of time headway. Participants (N = 40, aged 19 to 30) drove in a simulator behind a vehicle travelling at 50 km/h at set time headways ranging from 0.5 seconds to 4.0 seconds. After each drive ratings of task difficulty, risk, comfort, and effort were collected. In addition participants were asked to drive at the time headway they preferred. In order to assess familiarity participants also drove on both the left and right hand side of the road and the role of driving experience was also examined. The results show support for a threshold awareness of task difficulty, risk, effort, and comfort in relation to time headway. Participant's ratings of these variables tended to be low or nil at large time headways, but then around the 2.0 second mark began to noticeably increase. Feelings of task difficulty, risk, and effort were also found to be highly correlated with each other. No effect of driving experience or side of the road was found. (C) 2010 Elsevier Ltd. All rights reserved