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Mike Wheals

Manager, Railway Systems GEC Digital

In February 1984, GEC Railway Signals received an order from the State Rail Authority of NSW for the re-signalling of the Illawarra line. As part of that contract, GEC Digital provide the Train Describer Computer System, and the Telemetry system.

The Train Describer was fully designed in Australia, based on a BR specification, but with many enhancements suggested by the SRA and GEC. The Telemetry is the GEC General Signal Mark 111 system, newly developed in the UK, and customized and manufactured in Australia.

The Illawarra line train describer covers the area from south of Waterfall to Port Kembla. This area consists of double track bi-directionally signalled, double track uni-directionally signalled and single sections. There are fringe boxes at Waterfall and the branch line at Unanderra. Port Kembla is a terminus.

Provision is made for extension of the control area to include the Unanderra branch as far as Dapto, Moss Vale and Maldon.

The train describer is required to track trains throughout the system. Trains may enter the system at the fringe boxes and at any of the various sidings. Trains are identified by a four character code (unique on a daily basis) which is extracted from timetable information or manually entered by the operator. Trains proceeding without a description are identified with a special code of four asterisks.

Associated with each running signal is a train descriptior. berth. Train descriptions are stepped from berth to berth in response to field indications received via the telemetry and in accordance with the stepping tables.

Signal berth contents, i.e., train descriptions are displayed on the mimic panel and on the VDU area maps. Other information such as signal aspects, lie of points, routes set, track occupancy are also displayed.

Selected berths are designated as reporting points (generally platform berths at specified stations). At these points the Train Describer informs the Automatic Train Reporting System of train arrival and departure.

Operator VDU's are located in the Main Box at Wollongong and in the Fringe Boxes. Various commands are available to the operators. The set of commands available at the Fringe Boxes is different to that available at the Main Box. Such commands include berth interrogation, cancel train description, interpose train description acknowledgement of alarms etc.