Effects of Simulated Day and Night Driving on the Speed Differential in Tangent–Curve Transition: A Pilot Study Using Driving Simulator

Objective: The pilot study described in this article aimed to analyze the driver speed profile for evaluation of road design consistency during simulated day and nighttime driving. The research, carried out using a driving simulator, was developed with the overall objectives of evaluating the speed differential during simulated nighttime driving for the identification of critical road situations not detected by design consistency evaluation during simulated daytime driving. Methods: An existing 2-lane rural road, where high accident rates were recorded during nighttime, was implemented in the driving simulator of the Inter-University Research Centre of Road Safety (CRISS) and the drivers’ speed profiles were recorded in both simulated day and nighttime driving conditions over the 39 tangent–curve configurations that composed the road alignment. Results: The analysis of the speed differential based on the 85MSR (Maximum Speed Reduction) indicator during simulated daytime driving was not able to identify critical road situations that the same analysis revealed during the simulated nighttime driving. Such results occurred for most of the tangent–curve configurations. Conclusions: The study demonstrated that limiting the speed analysis only to daytime driving conditions cannot exclude the possibility that during nighttime driving some road configurations could become unsafe. The findings of the study highlight the need to carry out design consistency evaluations for nighttime driving conditions.