Brighton Park Crossing - Interlocking and Control Hardware

Interlocking and Control Hardware

For the vital aspects of the interlocking, the Geographic Signal System (GEO) device was applied. Non-vital communications between GEO devices included Wayside Access Gateways (WAG) and Ethernet Spread Spectrum Radios (ESSR.) Some logic control as well as event data recording is supplied by the Safetran Event Analyzer Recorder (SEAR2.) A number of different I/O devices are used, including Unipolar I/O (UIO.) Site monitoring and physical control is provided through large metal panels with numerous lights and switches which depict the rail control and indication points.

The vital aspects of the Brighton Park crossing is kept fault isolated from the non-vital parts of the crossing. In the event there is a hardware, software, or power fault within the vital systems, the crossing goes to the least permissive, safest state – usually with STOP signals being presented to locomotives and with crossing gate arms down with lights and bells.

There are also large control panels with many lamps and switches which operators may use to alter the flow aspects of locomotives through the Brighton Park crossing and the surrounding region. The control panels are inscribed with a depiction of the rails, and there are numerous switches, some of which can be used to instigate hardware and software testing of lamps and other devices.

In the event of a non-vital hardware, software, or power fault, the crossing may or may not be taken to a less permissive state depending upon the nature of the non-vital fault and the Rail company’s policies.

If communication to an Event Recorder is lost, for example, the maximum safe civil speed restriction in effect can continue to be used by locomotives since the lack of remote access to any such non-vital device does not impact vital safety.

If one or more vital GEO devices were to lose non-vital communications with another GEO device further down the line, however, the interlocking would go to a less permissive state since information about track occupancy and other things further down the track would become obsolete and then unknown.

The Brighton Park / Pershing Main project consists of many GEO boxes, WAGs, spread spectrum radios, Event Recorders, and other devices, all of which work to assist in the automating of this section of Chicago’s extensive rail infrastructure.