TESTING SPEED REDUCTION DESIGNS FOR 80 KILOMETER PER HOUR ROADS WITH SIMULATOR

Reduction of driving speeds offers an important opportunity to improve traffic safety on rural 80 km/hr roads. An experimental project in Drenthe was aimed at developing measures to reduce speed effectively without significantly reducing driving comfort at speeds up to 80 km/hr. Some variants of proposed infrastructure measures were tested in a driving simulator before actual application. Experimental conditions consisted of two lane widths (2.75 and 2.25 m) and three experimental layouts of edge strips: one with a continuous profiled road marking, one with small lateral rumble strips every 5 m, and one every 10 m. On entering this edge strip (the 2.75-m lane had a strip of 0.20 m and the 2.25-m lane one of 0.70 m) auditive feedback by means of sound and steering wheel vibration was generated. A conventional 80 km/hr road (lane width 2.75 m) with standard road delineation served as control condition. Some subjects were instructed to drive in a relaxed manner, and the others were instructed to drive as if under time pressure. The results show that the narrow lane width (2.25 m with a 0.70-m edge strip) reduces speed the most and is fairly resistant to effects of adaptation. Moreover, the narrow lane width especially reduces the speeds of drivers under time pressure, implying that in practice speed variance may be reduced. The different layouts of the edge strips reveal relatively small differences in driving behavior. It is concluded that the basic design elements as developed in this project offer a good prospect for reducing driving speeds in practice.