Assessing seriousness of road destruction and signal control algorithm under disasters

In order to secure emergency traffic routes under a natural disaster, it is necessary to restrict the vehicle flow into the disaster area. It is also required to set up detours, depending on the seriousness of road destruction. For that purpose, it is important to asses how seriously roads and bridges are damaged, in addition to implementing optimal signal control, referencing a variety of databases. The Hanshin and Awaji Earthquake of January 1995 brought the biggest damage in the post-war history of Japan. It has not only reminded us of the terror of fire hazards in large cities but has also presented many problems to solve. In that earthquake, the surface traffic network was cut into pieces because of damaged highways, roads being closed by collapsed buildings and damaged railroads, including the Shinkansen and others. People rushed into the limited number of available roads and the resulting severe traffic jams seriously affected rescue and restoration work in the disaster area. We have learnt the lesson that it is of critical importance to secure emergency traffic routes immediately after the disaster. Based on this lesson, the Tokyo Metropolitan Police Department has developed an advanced system featuring seismometers and image-processing vehicle detectors for assessing the seriousness of road destruction. Another newly developed system is the database-based signal control system which is to be run in a disaster. Both systems together are referred to as the "Disaster Management System". This paper presents an outline of this system.