Traffic-calming measures affecting perceived speed in approaching bends on-field validated virtual environment

With the aim of reducing the number of road traffic deaths around the world, the United Nations General Assembly proclaimed 2011-2020 the Decade of Action for Road Safety. Excessive speed is one of the main problems to overcome. The aim of this study was to test the effectiveness of traffic-calming measures in reducing drivers' speed along a road with a dangerous bend in an inland area near Venice, Italy. The driving simulator of the Transportation Laboratory of the University of Padua and the simulated scenario were validated by reproducing the study site environment. A driving simulator experiment was conducted to analyze changes in speed profiles associated with various countermeasures: evenly spaced guideposts, tall guideposts, narrowing guideposts, and dragon's teeth markings. Tall and narrowing guideposts served to reduce drivers' speed by up to 2.7 km/h. Unlike tall guideposts, which produced no detrimental effect on drivers' behavior, narrowing guideposts led drivers to occupy more variable positions within the lane. In view of this at-risk behavior, the convenience of the option to produce an apparent narrowing of the lane on real roads was discussed. This study found that the use of driving simulators was a reliable research tool to reproduce drivers' real behavior. The study also provided effective, low-cost measures to counteract excessive speed on dangerous road sections.