Rumble strips in centre of the lane and the effect on sleepy drivers.

The aim of this study was to describe the effects of sleep loss on behavioural and subjective indicators of sleepiness on a road containing a milled rumble strip in the centre of the lane. Particular attention was paid to behavioural and subjective indicators of sleepiness when using the centre lane rumble strip, and to possible erratic driving behaviour when hitting a rumble strip. In total 9 regular shift workers drove during the morning hours after a full night shift and after a full night sleep. The order was balanced. The experiment was conducted in a moving base driving simulator on rural roads with a road width of 6.5 and 9 meters. Out of the 1,636 rumble strip hits that occurred during the study, no indications of erratic driving behaviour associated with the jolt caused by making contact with the centre lane rumble strip could be found. Comparing the alert condition with the sleep deprived condition, both the standard deviation of lateral position (SDLP) and the Karolinska Sleepiness Scale (KSS) increased for sleepy drivers. For the two road widths, the drivers drove closer to the centre line on the 6.5-meter road. The KSS and the SDLP increased with time on task. This simulator study indicates that rumble strips in the centre of the lane may be an alternative to centreline and edgeline rumble strips on narrow roads.