Australian Railway Signalling - Victoria

Victoria

The railways of Victoria use a mix of railway signalling practices: British route signalling with home and distant signals (2 position signalling) and American speed signalling (3 position signalling).

Semaphore signals were used on the very first railway lines, but only a bare minimum were provided as the time interval system being relied upon instead. The first interlocking of signals to protect trains was provided in 1874, as before this time conflicting moves could be made. The design of the signals also progressed, with the disc type siding signals first introduced in 1885, and the lower quadrant somersault type main line signals adopted in 1887, both of which are still in use today. Green was not adopted as the All Right colour until 1898, with white being used before this time. Red was the usually colour of all signal arms, until yellow was chosen as the colour for distant signals in 1926, with full adoption made in 1930. Colour light signals first appeared in 1918, and by 1924 they were the standard for new installations.

The safeworking of trains between stations on the early lines was time interval working, where a train would be allowed to leave a given time after the train before it. With heavier traffic this method became unsafe, with Staff and Ticket working on single lines adopted from 1873, and telegraph block working from 1878 on double lines. Both of these systems ensured that only one train would be in a section of track at one time. Telegraphic block working was then replaced with Winters Block working between 1883 and 1888, a system that is a predecessor of the Double Line Block system which is still used today. Later years saw variations made to the Staff and Ticket system, with busier lines provided with Electric Staff working which provided greater safely when more trains ran.

Heavier suburban traffic on the Melbourne network saw a greater strain on the block working then used, which required a large number of manned signal boxes to enable trains to run close together. As a result it was decided to adopt power signalling under the Automatic Block System (ABS) of safeworking, where the presence of trains automatically control the signals after them, providing a safe distance between trains. Introduced from 1915, the system was based on American speed signalling practice with GRS2A upper quadrant mechanical signals with two arms able to indicate up to 5 different speed aspects to train drivers. These signals were later replaced by colour light signals which are the standard today, but the old mechanical style remained until 2001.

A variant of the Automatic Block System, Automatic and Track Control (ATC) has since been introduced, which provides the same benefits as ABS on single lines of track, while still ensuring only one train in a section at a time. Centralised Traffic Control was also introduced in the 1960s on the new standard gauge line to Albury, and then on the main interstate line to Adelaide, allowing trains to be directed from a distance.

Today little mechanical signalling remains, with local signal boxes controlling signals abolished from many areas as part of the Regional Fast Rail project. Today the suburban network and busier regional lines use variants of Automatic Block Signalling, while quieter lines use the Train Staff and Ticket or Train Order systems of safeworking. Train protection has also progressed, with the Train Protection & Warning System also introduced on major passenger lines.