The Effect on Lane Utilization and Traffic Capacity of Adding an Auxiliary Lane

Chuo Expressway is one of the main arterial expressways connecting between Tokyo and Nagoya through some resort areas and mountainous areas, so the traffic volume on the expressway reaches to 100,000 per day on holiday and weekends. The traffic congestions, which have more than 30 km length, occur frequently under the heavy traffic volume. As a measure for reducing traffic congestion at the Kobotoke Tunnel on the Chuo Expressway bound for east, the arrangement of operational lanes on a trial basis for the period of one year and two months from 28th Jan, 2010 to the end of March, 2011. This is the first trial of such kind in Japan. The distinctive feature of this trial is how the operational lanes are shifted. This section of the expressway has two mainline and one climbing lane is not in high use and does not significantly enhance the traffic capacity of this section. During this period, the climbing lane is used as the slow lane and the original passing lane as the third operational lane. At the exit of the climbing lane, it returns to the original dual carriageway arrangement. In this way, three lanes are fully utilized to enhance the capacity of this section. This trial arrangement is so far proving its effect of preventing or alleviating traffic congestion.