On the A16 motorway near the city of Breda, the Dutch Ministry of Transport has installed an automatic fog-signalling system with the aim to elicit safer driving behaviour during fog. On an experimental road section of 10 km, sensors have been installed on twenty different locations along the road, which continuously measure the visibility range. During fog, the system displays an explicit fog warning on matrix signs above the road, and also a maximum speed which depends on the actually available visibility range. This report deals with an evaluation study of the system in terms of driving behaviour, which has been carried out for a period of two years (February 1992 - March 1994). The results reveal that the system has results reveal that the system has a positive effect on speed choice: it causes a larger decrease of the mean speed than the reduced visibility itself. The effect sizes that were found are about 8 - 10 kmh. The effects found, indicate a behavioural change in a safe direction.
Samenvatting