A field study was designed to investigate and compare the potential or sensitivity of the selected assessment methods to reflect the effects of different S-IVIS on driver behaviour in rural and in urban environment. More specifically, (1) the data were collected in real traffic, (2) the drivers included so-called average as well as elderly drivers, (3) the effects of increasing the demand of the visual task and of the cognitive task on driver performance were quantified, and (4) evaluations were based on vehicle data, observations and drivers' reports. Driving performance is often measured by means of objective measurements such as speed, lane position, and steering frequency. However, because in busy traffic such measures may be affected by various external factors rather than by driver distraction or overload, also a method including subjective observations or ratings by driver has been discussed. In this paper the emphasis is made on the drivers reports i.e. their own estimations of their driving performance while using surrogate IVIS. The main results of this study showed that the drivers rated their driving performance worse on average when performing secondary task. However, the differences were relatively small. In addition, there were differences in self-reported driving quality between average and elderly drivers when considering same kind of behavioural changes. For example, the results suggested that in dangerous situations elderly drivers reduced their ratings very little or not at all. This was also the case with average drivers in inappropriate interaction with VRU. Perhaps the drivers are not aware of all behavioural changes in their driving performance or they do not consider some changes in driving behaviour to be safety related. Consequently, other measures than driver ratings are needed to assess the effects on an IVIS on driving performance and traffic safety. For the covering abstract see ITRD E137489.
Abstract