Installation of an Auxiliary Overtaking Lane as a Measure Against Congestion at Motorway Bottlenecks

In Japan, auxiliary lane has been installed with the aim of correcting the lane utilization and increasing traffic capacity as a measure against traffic congestion at sag section of multi-lane motorways. The objective of this paper is to examine an effective method of installing an auxiliary overtaking lane for bottlenecks on motorways. First, a microscopic traffic flow simulation model is calibrated using observation data. Then, the simulation model is applied to study the appropriate installation method (installation location and length, etc.) of auxiliary overtaking lane as a measure against traffic congestion in section where sag is a bottleneck in capacity. As a result, auxiliary overtaking lane should be installed 400m upstream from the beginning of the vertical curve, and should be ended 0.6 to 1.0km from the end of the vertical curve, with a total length of 1.5 to 2.0km.