This paper describes the advantageous effect of providing location information on traffic bottleneck to drivers, using the variable message sign (VMS). This measure for mitigation of traffic congestion on motorways is introduced at bottlenecks caused by sags and tunnels. The VMS displays the warning messages, such as 300m ahead, congested queue ends! or Restore the speed please! in order to make drivers sensitive to up grade and to encourage drivers to accelerate at the end of the queue. There are two types of capacities at bottlenecks on the motorways. One is the pre-queue breakdown flow rate, and the other is the queue discharge flow rate (QDFR) during congestion after the breakdown occurred at a bottleneck. Thanks to the measure using the VMS, the queue discharge flow rate at a bottleneck increased by 3-13 percent. This measure is currently implemented at 50 bottlenecks on motorways over the country, because it is very cost effective. The results of factor analyses of the queue discharge flow rate are as follows.During the nighttime, the queue discharge flow rate is higher than that during the daytime. The queue discharge flow rate of drivers who are caughtin the congested queue over 30 minutes is lower than that of drivers who are caught in the congested queue less than 30 minutes. The results of effectiveness analyses of the measure using VMS by queue discharge flow rate are as follows. The incremental queue discharge flow rate at a bottleneck,where the queue discharge flow rate is higher, yields smaller than that at a bottleneck, where the queue discharge flow rate is lower. The incremental queue discharge flow rate during the daytime is larger than that during the nighttime.
Abstract