A driving simulator was used for investigating the influence of sight distance on subjects' speed and lateral position. The sight distance was varied by simulated fog delimiting the sight distance to approximately 480 m, 120 m, 60 m and 30 m. Sight distance was found to influence subjects' mean speed, but not their lateral position and lateral variation. The correlation between lateral position in free-sight conditions and conditions of reduced sight (based on 100 m intervals of the driving route) was positive but it declined with decreasing sight distance. This finding strongly suggested that the pattern of lateral variation differed between sight distances. Furthermore short sight distances resulted in a weaker relationship between the angular deflection of the road and lateral position than longer ones. The mean z-scores in 100-m intervals of the driving route indicated that lateral deviations were both less sensitive to road curvature and less consistent between subjects for shorter sight distances than for longer ones. This result may suggest that reduced sight increases the amount of random variation in the subjects' lateral positions.
Abstract