City centers / Sub-centers
These centers control traffic in areas located away from traffic control center headquaters. The information collected by these centers os trancmitted to the headquater centers; their major functions are simillar to those of the headquater centers with which they are linked.
Traffic control centers in neighbouring prefecture
Traffic control centers exchange traffic data with neighbouring prefectures. This data exchange provides the basis for the synchronous operation of traffic signal controllers located on the borders between prefectures and helps ensure that drivers are supplied with the infomation they need.
Other agency centers
Traffic control centers cooperate with the centers of other agencies administering expressways in and between cities.