In addition, the following overrun protection measures are taken in view of the fact that trains
may perform improper braking operations and overrun stop signals.
* Protection sections are secured by positioning home signals 100 m or more from the outermost shunt of the station.
* 150 m overrun protection sections or safety sidings are established inside departure signals for incoming trains.
Relay interlocking devices are considered ideal interlocking devices for the following reasons, due to their superior safety and work efficiency.
* The various locking functions required of interlocking devices can be ensured.
* Multiple routes can be controlled with a short configuration time (approximately 6 seconds) by using electric shunting machines.
* The signal boxes for large stations can be centralized in a single location.
* Operating conditions can be understood with control panel displays, thereby facilitating route handling.
However, with recent advances in electronic technology, electronic interlocking devices which feature computer-based programmed route control (PRC) are being adopted. When installing interlocking devices, operation planners, should take the following items into account to enable the smooth execution of yard work from the aspect of the users.
* Methods of using departure and arrival tracks and specification of through tracks (main lines)
* Signal installment positions and overrun protection section ranges and directions
* Confirming the effective length of track
* Shunting work methods and telecommunication facilities for communication
9 Traffic Control
Traffic control consists of operating a group of trains according to a planned train diagram, and is performed by train dispatchers who must be constantly aware of train running conditions and take appropriate measures to restore normal running conditions as quickly as possible when trains become delayed, etc.
(1) Basic train running control format
Fig. 12 shows the basic format for train running control. Here, commands and information are transmitted back and forth between the train dispatcher, station master and
