Australian railway signalling varies between the States of Australia, because the individual States are responsible for the railway systems within their own borders, with, historically, no need to co-ordinate between states except at the boundaries.
Mechanical signalling in all States followed British practice using route signalling with slight differences between States. The basic running signal was the Home signal, an absolute stop signal with a red arm. Route signalling was used to indicate the line to be taken at junctions. Advance warning was given by a Distant signals. Subsidiary signals for shunting moves differed between States, just as they did between the different railway companies in Britain.
Signalling practice, however, diverged with the introduction of power signalling into each State. New South Wales was first significant adopter of power signalling. It adopted the then standard international practice of displaying three aspects using home above distant signals; this developed into an integrated mechanical/power signalling practice based on route signalling. Victoria and South Australia adopted US speed signalling when they introduced power signalling in 1915; this was integrated into their route signalling based mechanical signalling. Queensland, Tasmania, and Western Australia used power signals as a direct replacement for mechanical signals. Queensland subsequently adopted British style power signalling in the 1960s when it began installing power signalling on a large scale; again this is a route based signalling system integrated with their mechanical signals. Western Australia adopted British style power signalling in the Perth suburban area when the suburban network was electrified. When the Adelaide suburban area was resignalled, South Australia adopted a system using British style light signals displaying US speed signalling aspects for the suburban lines. The result is that the signal aspects (patterns of lights) and indications (meanings) differ widely, both between the former State systems and even within States.
Mechanical signalling has effectively vanished from the Australian non-preserved railway scene, leaving the divergent power signalling schemes. This causes conflicts between the systems. For example, in New South Wales a green-over-red coloured light signal means "caution", indicating the next signal is at "stop". In Victoria, that same aspect means "clear normal speed", indicating the next signal is anything but at "stop". On the Main South Line from Sydney, single-light signals are now exclusively used from Spring Creek bridge (south of Galong) to Albury on the Victorian border that forms a buffer zone between the conflicting signal indications of each state. The buffer zone is a byproduct of NSW signalling system, it being in single light colour light signalling.
South Australia uses two primary forms of signalling. Nearly all signal boxes in South Australia have now been closed, and most rail traffic is coordinated through centralised traffic control (CTC) systems, either under the Australian Rail Track Corporation (ARTC) from Mile End or Adelaide Metro control from Adelaide. Where the two networks interface, such as at the Goodwood level crossing or at Torrens Junction, control is usually by the ARTC after release from Adelaide Metro.
The Western Australian system is the simplest to understand, and the complexities of leading position lights and other odd attachments to signalling apparatus have been either eradicated or were never part of it. Switchlocks are used to enter sidings from mainline CTC territory, such as the CBH Group yard terminal on the standard gauge railway. The train controller must release the switchlock, thus interlocking the signals to stop, which is similar to the system in Queensland. Perth's urban passenger network is operated by the Public Transport Authority and the rules are almost identical to those of freightlines.
Signalling comparison +Table comparing the main aspects used in each system to show similar meanings. Note that the names used for the indication names (e.g. 'Clear') are not necessarily used by any individual system. See individual states for more information and clarification.Standard NameNSWQLDVICSAWADouble ColourSingle ColourTwo AspectThree AspectRouteSpeedMain aspectsClearProceed(CBTC)Preliminary medium (NSW Double-Light Colour Light only)Proceed, next signal displays at least a medium indication - - - - - - -Medium (NSW) Preliminary cautionProceed, but be ready to stop at the signal after next -* -* -CautionProceed, but be ready to stop at the next signalStopStop, do not proceedSpeed restricted aspectsLow speed (NSW) Medium speed warningNSW: Proceed ready to stop at the next signal. The line immediately beyond the next signal may be occupied. Proceed at medium speed, but be ready to stop at the next signal(25)(25)(40) -(40) -(35) -Reduce to medium speedProceed at normal speed, but slow down to medium speed before the next signal - - - -(40) -(35) -Clear medium speedProceed at medium speed - - - -(40) -(35) -Shunt aspectsCalling on (NSW) ShuntNSW: Proceed past running signal, route is set and points are locked. Line ahead may be occupied Continue Through signal on SightClose up (call on)NSW: Proceed ready to stop at the next signal. The line immediately beyond the next signal may be occupied. Continue on sight to train ahead^^^^^Turnout aspects / Add-on indicatorsTurnout left ClearTrain must slow for turnout to the left
after signal - -† † †††Turnout right ClearTrain must slow for turnout to the right
after signal -†††Turnout left Advance cautionTrain must slow for turnout to the left
after signal; expect
stop after one more
signal‡† - - - - -Turnout right Advance cautionTrain must slow for turnout to the right
after signal; expect
stop after one more
signal† - - -Turnout left CautionTrain must slow for turnout to the left
after signal; expect
stop at next signal‡† -† †††Turnout Right CautionTrain must slow for turnout to the right
after signal; expect
stop at next signal† -††Turnout warning Signal (left)Train must prepare to diverge after next signal - Turnout warning Signal (right)Train must prepare to diverge after next signal " - " means that there is no equivalent in that system
" * " means the meaning is significantly different, but can be used to mean the same thing in some circumstances.
"(##)" Indicates the speed limit past this signal (in km/h)
" ^ " System uses signal above for this role.
" † " Signal can use a Theatre Display type route indicator or a Feather type.
" ‡ " Signal can be provided with or without a Theatre Display Indicator.
New South Wales Railway signals in New South Wales broadly follow British route signaling practice, with certain American influences and local innovations. The following systems are currently in use, listed in chronological order of introduction: two-position lower quadrant semaphore, three-position upper quadrant semaphore, Double Light Colour Light and Single Light Colour Light.
Double Light signals are capable of showing more indications than Single Light signals, therefore Double Light signals are more appropriate for use in dense traffic areas, such as the Sydney metropolitan area, and Single Light signals for the less intense areas. However combinations of the different types may be found at the same interlocking locations.
Systems of train signalling New South Wales signalling systems generally follow British precepts, however American influence has increased somewhat since the 1990s. Originally trains ran on the time-interval system and authority of the timetable. From the early 1870s, several near-misses and minor derailments led to serious discussion of improved safe-working arrangements and the implementation of interlocking.
Despite this, very little action was taken until 1877, when a new rule book including the Staff & Ticket and Block Telegraph systems was finally printed. The ink was barely dry on 30 January 1878 when two trains collided head-on at Emu Plains, killing three. This put an end to timetable working on single lines. Absolute Block Telegraph for double lines came in 1879, Saxby & Farmer's mechanical interlocking in 1881, Tyer's Electric Tablet in 1888 (lasting until 1959) and the Electric Staff system in 1891.
Tyer's One-Wire Block began to replace the original Preece's Patent instruments from 1891. Sykes' Lock & Block was used on a few suburban sections from 1900. Tyer's Three-Wire Block was used for permissive block working on the Up Relief line from Concord West to North Strathfield Junction from 1911 until 1983. In 1913, the two-wire New South Wales Standard Block, which was similar in principle to Lock & Block, became the standard for new installations.
It was unique in having a fourth position, known as Train Arrived, and a different sequence of operation to standard British arrangements.Department of Railways, New South Wales: Regulations for Train Signalling by Block Telegraph on Double Lines, 1967 The last of these instruments were removed from Exeter, Bundanoon and Wingello on the Main South line in 2007. By 1907, the majority of signalling equipment, including signals and mechanical lever frames, were being manufactured in-house under the direction of the English-born signal engineer, C.L.N.F. Wilkin. The NSWR Signal Engineer's Branch supplanted McKenzie & Holland as the principal supplier in most installations.
Power signalling Power signalling arrived in 1910 in Sydney Yard, with the commissioning of (Sydney) Station Box. This installation was electro-pneumatic and controlled from a miniature lever frame supplied by the McKenzie, Holland & Westinghouse Power Signal Co. of Worcester, England. Although the lines were not continuously track-circuited and absolute block telegraph remained between signal boxes, there was some control of signals by track circuit and treadle. Upon its replacement by a 432 lever pistol grip power frame in the new Sydney Station West signal box in the late 1920s, the original miniature lever frame was divided into smaller sections for reuse at other locations. The disused 'Station Box' remained in position for decades after its retirement, but has now been demolished, along with its successor.
Track Circuit Block On 22 June 1913, the first automatic signals in Australia were brought into use between Eveleigh Loco Junction (Illawarra Junction) and Sydenham, replacing Tyer's One-Wire Block. These signals were of the two-arm home and distant type. From that time on, a form of Track Circuit Block (TCB) worked from mechanical and power signalboxes, with the gradual spread of automatic signalling between stations, became the standard for new installations, initially with semaphore but later colour light signals.
In practice, the term Track Circuit Block was generally shortened to 'Track Block', of which there were a number of (mainly administrative) variations in the rules, such as Double Line Track Block and Single Line Track Block. Track Circuit Block, now known officially as the Rail Vehicle Detection system,Rail Infrastructure Corporation (now RailCorp) Network Rules, 2002 remains the standard system of train signalling on all main lines in the Transport Asset Holding Entity network.
Absolute-Permissive Block The American Absolute-Permissive Block system, known locally as Single Line Automatic, was installed on the Molong to Dubbo line by C.B. Byles in 1925. Train movements on the line were regulated by a Train Controller at Yeoval, who directed the issue of crossing orders for trains on the line. While a technical success, the traffic density did not warrant the cost of maintaining the signalling system. It was replaced by the first installation of the Divisible Miniature Electric Staff system in 1933.
Signalboxes in 2012