A simulator study was conducted to investigate the implementation of a new law which prescribes a speed limit of 30 km/h when passing buses equipped with a 30-sign and flashing lights. It was shown that the drivers follow the rule better when they pass a bus on their own side than when the bus was standing on the opposite side of the road. The slowest mean speeds were found when passing a bus on a road with a speed limit of 70 km/h. The highest speed reduction, however, was found when the posted speed limit was 90 km/h. A bus without signage did not induce the same speed reduction as a bus with signage, which means that the drivers were aware of the meaning of the signage. Driving behaviour showed that the flashing lights are of importance, because the drivers in the study started braking before the 30-sign was readable.