Project office `Sytwende' plans to build part of the road RW14 (between the Vliet and the railroad The Hague-Amsterdam) as a tunnel, with the road surface partially at ground level. The tunnel is interrupted twice by level signalized intersections. In a previous analysis, a number of shortcomings of the design were identified (Kaptein & Theeuwes, 1996b), which has led to a number of design changes. Under contract with the Dutch Ministry of Transport, Public Works and Water Management the present study investigated to what extent the adjusted design would lead to unsafe driving behaviour. To this end the behavioural consequences were assessed of two proposed design options: one based on a speed limit of 70 km/h for the entire road, and one based on a speed limit of 50 km/h for the central part of the road. Results showed that all design alternatives led to serious speed limit violations, and consequently to unsafe driving behaviour. This is not the result of specific problems associated with the tunnel design, but due to the general road layout. The road looks too much like a motor way. The view on the main road from the side roads is sufficient, assuming that speed limits on the main road are not violated too much. The observed violations should therefore be prevented. Further research should establish how driving speed can be decreased, how to evoke more correct expectations by road users, and whether this would solve the observed problems.
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