The signal control system with radio in a disaster

In the Hanshin and Awaji Earthquake of January 17, 1995, 93% of the area control units in Kobe were forced to stop their operation because of telephone line to signal controller or power supply failure though most of the signals survived the disaster. The current Traffic Control Center of Tokyo Metropolitan Police Department (TMPD) is situated in a building designed to survive large earthquakes. Its machine room, for instance, has a quakeproof structure, and the units constituting the system and the LAN connecting the system units are configured based on multiplex concept. However, signals will be forced to turn off if power supply lines are disconnected and the centralized control will be lost if wired communication lines fail. Thereby making it very difficult to develop and carry out necessary traffic control measures in the disaster area, such as restricting entrance of unauthorized vehicles into the area and securing emergency traffic routes. These control measures are indispensable for saving people and implementing restoration work effectively. In order to minimize traffic confusions and secondary sufferings resulting from failure on wired communication lines or power feed during and after serious natural disasters, the TMPD has developed and successfully installed a new signal control system featuring the wireless communication system and automatic start-up engine driven generator. This paper reports on this new system.