Merja Penttinen

Effects of variable message signs for slippery road conditions on reported driver behaviour

A field study by Rama and Kulmala (Rama, P., Kulmala, R. (2000). Effects of variable message signs for slippery road conditions on driving speed and headways. Transportation Research, Part F, 3, 85–94.) showed that a variable message sign warning about slippery road conditions reduced the mean speed by 1–2 km/h. The study also showed that a variable message sign recommending a minimum headway between vehicles decreased the proportion of short headways. However, the signs may have other effects on driver behaviour besides those measurable in terms of speed and headway, and this study was designed to investigate such potential effects. In total, 114 drivers who had encountered the slippery road condition sign and 111 drivers who had encountered the sign showing recommended minimum headway in adverse road surface conditions were interviewed. The results suggested that these variable message signs do indeed have other effects, such as the refocusing of attention to seek cues on potential hazards, testing the slipperiness of the road, and more careful passing behaviour. On the other hand, the results suggested that driving speed and headway are essential variables with which many other variables correlate.

Effects of experience with retroreflectors on recognition of nighttime pedestrians: comparison of driver performance in Finland and Michigan

Abstract This field study replicated a recent experiment by Luoma, Schumann and Traube [(1996) Effects of retroreflector positioning on nighttime recognition of pedestrians. Accident Analysis and Prevention, 28, 377-383.] on the effects of retroreflector positioning on nighttime recognition of pedestrians. The key difference between the two studies was that Finnish drivers who have substantial experience with different pedestrian retroreflectors were used in the present study, while Michigan drivers—whose experience with pedestrian retroreflectors is more limited—were used in the previous study. The subject’s task was to press a response button whenever he recognized a pedestrian on or alongside the road, while in a car, with low-beam lamps on, that was driven on a dark road. The results showed that the main effects were the same as found in the previous study. Specifically, the retroreflective markings attached to the limbs led to significantly longer recognition distances than when the retroreflective markings were attached to the torso, and a pedestrian was more recognizable while crossing the road than while approaching the subject vehicle. However, the differences between the recognition distances produced by the various retroreflector configurations were smaller in Finland than in Michigan, and the Finnish subjects more frequently responded incorrectly.