| Hokkaido Prefecture is characterized by a higher fatality rate among serious accidents relative to other regions of Japan. One reason for this high fatality rate is the fact that most highways in Hokkaido Prefecture are two-lane roads、 and such highways are prone to head-on collisions、 run-off-the-road accidents、 collisions with roadside structures、 and other types of fatal accidents that characterize suburban areas. In the U.S.、 to reduce the number of such accidents、 "rumble strips" have been increasingly installed along roads. Rumble strips are grooved belt-like sections of pavement installed along the centerline or shoulder to warn drivers who are in danger of crossing the centerline or running onto the shoulder、 by means of noise and vibration. They are considered an effective countermeasure to driver drowsiness and inattention. This paper reports the results of a driving test on a test track、 and a camera observation test on a national highway. The tests were conducted to examine the applicability of rumble strips as a countermeasure to head-on collisions. We had road users drive/ride on the test track with rumble strips of three different depths: 9 mm、 12 mm、 and 15 mm. During their driving、 we conducted physical quantitative measurements for objective evaluation of each depth. After their driving、 we gave the users a questionnaire to assess their subjective evaluation of safety for each depth. It revealed that drivers of two-wheeled vehicles did not feel the strips to be dangerous when they were 12 mm deep or shallower. This depth was adopted as a standard because drivers did not rate centerline strips of this depth as dangerous. Rumble strips were judged to be an effective countermeasure to head-on collisions、 in terms of smooth driving and cost-benefit、 through experimental installation on a national highway. |
