With support from TrygFonden, DTU Transport has performed a study on distracted driving. The study consisted of partly a literature study and partly an experimental study carried out in DTU Transport’s car driving simulator. The purpose of the literature study was to establish an overview of the existing research-based knowledge about distracted driving. The purpose of the simulator study was to contribute with new knowledge within relevant areas identified by means of the literature study. A prerequisite for safe driving is that the driver pays attention to the traffic. Nonetheless, practically all drivers carry out different activities while driving, activities which are not necessary for the driving itself, e.g. chatting with passengers and eating and drinking. It is estimated that the drivers are engaged in different kinds of distracting activities during approximately 30 % of the time the car is moving. The distractions impair the driver’s attention on the traffic. In this way the risk of overlooking another road user, reacting too late or inadequately and of getting involved in an accident is increased. However, studies indicate that distraction from within the cabin is a decisive factor in approximately 30 % of all road accidents. Distraction is a driver’s temporary state of inattention caused by activities or events that are not necessary for the driving itself. Distraction differs from longer lasting states of inattention due to e.g. fatigue, influence of alcohol and illness. A distinction is made between the following four types of distractions: Visual, cognitive, motorical and auditory distraction. These four types of distractions are found in practice in different combinations depending on the type of activity involved. Writing an SMS involves for instance an element of visual distraction (watching the phone/the keyboard), an element of motorical distraction (pressing and possibly holding the phone) and an element of cognitive distraction (thinking of the content of the message). Distraction cannot be measured directly and must therefore be assessed based on changes in the driver’s behaviour or style of driving. The most commonly used measurements for distraction is lane position, speed, time of reaction, distance to the car ahead, using the mirrors, etc. Distractions can influence the driver’s ability to drive safely in several ways. Some distractors particularly influence the driver’s ability to collect the relevant information, others are important for the driver’s ability to process the collected information or influence the driver’s ability to carry out the relevant manoeuvres. The biggest difficulties arise when the driver needs to do two similar things at the same time and must use so many resources on the distracting activity that he lacks resources to drive safely To some extent, drivers intend to compensate for the distraction by e.g. lowering the speed. The compensation, however, is not enough to counteract an increased number of critical situations. This is among other things due to the drivers’ underestimation of the distraction level inherent to the different activities. Most of the distracting activities taking place inside the cabin are voluntary activities that can be avoided. Knowledge about the drivers’ attitude to these activities and the motives behind the activities are therefore an important element in the prevention of distraction-related road accidents. The existing knowledge within this field is very limited. Based on a comprehensive literature review, the existing knowledge about the following 11 sources of distraction is presented: cell phone, radio/music centre, MP3 player, navigation equipment, air-conditioning equipment, passengers, food, personal care, smoking and the like as well as road maps. For each distractor it is explained which type of distraction is involved and to which extent the distractor concerned is found to cause traffic accidents. It appears that activities that make the driver take his eyes off the road or divert his attention from the traffic, makes it particularly difficult for the driver to drive safely. The review furthermore shows that passenger distractions account for the majority of the distraction-related accidents, followed by distractions due to adjustment of the radio/music centre, cell phone use, adjustment of the airconditioning and consumption of food and beverages. This ranking, however, does not take into account the exposure. Nevertheless, it underlines that the efforts to prevent distraction-related accidents cannot only focus on the use of technological equipment, but should also include everyday activities such as chatting with the passengers and handling of the radio/music centre. Presently, cell phone use is the most examined source of distraction. Similarly to most of the other sources of distraction the existing knowledge is limited. In particular, further knowledge about how different types of distraction influence the driving performance in different situations and among different groups of drivers is needed. Furthermore, there is a lack of knowledge about the prevalence of the various sources of distraction and the individual distractors accident potential. In continuation of the literature study, the purpose of the simulator experiment was to elucidate whether different types of distractions influence the driving performance in different ways, and whether the driving performance is influenced in various ways depending on the complexity of the traffic situation. 24 test persons between 25 and 60 years of age participated in the experimental study carried out in DTU Transport’s car driving The study showed that the impact on the driving performance increased with the complexity of the distracting activity. Furthermore, the study showed that there was coherence between the type of distraction to which the test person was exposed and the way in which the dis traction influenced the driving performance. When the test person was exposed to a visual motorical distraction, it was thus the visual-motorical aspects of the driving that were influenced, expressed in the form of zigzag driving. Furthermore the effect was bigger in case of a demanding distraction. A similar result was found for cognitive distractions where the braking time was significantly longer when the test person was exposed to complex cognitive dis tractions. The study result shows that all kinds of non-driving related activities are to be carried out with great care and in consideration of the traffic situation, so that the driver has the necessary resources at his disposal, in particular in the case of an unforeseen situation. (Author/publisher)
Abstract