In workzone areas on motorways, contraflow systems are already often applied, where traffic of one carriageway is guided to the other carriageway with decreased lane width, either partially (3-1 type workzone) or completely (4-0 type workzone). According to the Dutch guidelines for workzone areas, a contraflow system is only allowed to have a maximum length of 4 km. This study investigated the effects of long contraflow systems (up to 12 km) on driving behaviour. The study consisted of: (1) a driving simulator study investigating driving behaviour in long contraflow systems; both 3-1 type and 4-0 type workzones were included, both with two types of lane width; (2) video observations of real life situations from standard motorway to both contraflow systems; and (3) of driving with an instrumented car to study effects of both contraflow systems on real driving behaviour. In conclusion, in terms of driving behaviour and subjective measures, there is no reason to limit the length of contraflow systems to 4 km under all circumstances. For systems with a length up to 8 km, wider lanes and the single lane of the 3-1 system are to be preferred. For the 3-1 system with small lanes and for the 4-0 system, a length up to 4 km is to be preferred.
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