For safe driving, it is essential that the driver properly recognize pavement markings and other traffic control devices. At the same time, road surface conditions vary with weather conditions. In snowy regions, the road surface during winter can be compacted-snow, dry or wet. Under the compacted-snow condition, drivers are not able to see the pavement markings, and on rural highways, overtaking is an important maneuver. In autumn 2006 and winter 2007, the authors conducted driving tests on overtaking behavior and on subjective evaluation of safety under the dry and compacted-snow conditions on a 2-lane section and on a 2+2-lane section. Ten drivers participated in a test on a road section in service. A vehicle dynamics recorder was installed on a test vehicle that traveled both directions on a 19.0-km test section of a rural highway in Eastern Hokkaido, Japan. Ten male drivers drove the test vehicle under free-flow condition. On the 2+2-lane section, the test vehicle overtook a preceding vehicle. The driving behavior of the overtaking vehicle was recorded using a vehicle dynamics recorder on the rear seat. After each test run, the driver filled in a questionnaire on subjective safety. It was found that the velocity during overtaking is lower for the compacted-snow condition than for the dry condition, and that the variation in longitudinal and transverse acceleration was higher for the compacted-snow condition than for the dry condition. The subjective safety assessment value for the compacted-snow condition was lower than for the dry condition.
Abstract