Warning sound to affect perceived speed in approaching roundabouts: Experiments with a driving simulator

When examining facts concerning road safety, as stated by the United Nations General Assembly, one of the most important problems is vehicle speed. The aim of this work is to evaluate the potential influence of traffic-calming measures on drivers’ speed. In particular, attention focuses on warning sounds produced by communication between vehicles and infrastructures. A driving simulator experiment was used to test the effectiveness of three speeding countermeasures, located along the approach to a roundabout in a rural area, together with the control condition (i.e., no countermeasures, corresponding to the current configuration of the roundabout): a continuous pitch playing throughout driving along the road segment and pitches activated by vehicle detectors at either constant or wide-to-thin (decreasing) distances. Results showed that a continuous pitch is the most effective in reducing speed. Decreasing pitches still reduce speed to some extent, but constant spaced pitches only cause a small reduction in speed. Since continuous beeping seems to be more effective immediately after it starts, but becomes less effective either after a given time interval or as the driver approaches the hazard, then the same effect found with this particular setting should still be found with shorter but continuous beeping. Using a shorter beep should, at least in theory, reduce any feeling of annoyance in drivers, as is the case with an extended pitch.