Performance Evaluation for Rural Two-Plus-One–Lane Highway in a Cold, Snowy Region

Abstract

Hokkaido, Japan, is a cold, snowy island where winter lasts for approximately 5 months, from November to March. Road surfaces are usually dry, but frequently covered with compacted snow. A measure to improve existing two-lane highways to two-plus-one (2+1) lane highways by installing an auxiliary lane has been introduced to offer a better quality of service to road users. A sensitivity analysis was undertaken with a traffic flow microsimulation program, SIM-R, to evaluate the effectiveness of 2+1-lane highway sections, which were built by adding an auxiliary lane to rural two-lane highways, in a cold, snowy region. The road surface conditions under analysis were dry and covered with compacted snow. The hourly traffic volumes were changed from 100 to 1,000 vehicles per hour. Evaluation indicators were the average travel speed, the percentage of following vehicles, and the density of following vehicles. The results showed that the average travel speed decreased, the follower percentage increased, and the follower density increased as the hourly traffic volumes increased. Moreover, the road performance decreased on the road covered with compacted snow compared with the dry road. The installation of an auxiliary lane at certain intervals was also found to improve the level of service for two-lane highways on both the dry road and the road with compacted snow.