The last semaphores.
The last semaphore signals that I am aware of on Queensland Rail in the Brisbane area are on the single track Pinkenba line between Hendra and Ascot stations. They no longer operate, at least as far as I know as the line is also fitted with colour light signals.
Electric passenger services on this line terminate at Doomben station.
Semaphore signals were developed in the 19th century as an improved means of safe working on the railways, keeping trains separated by safe distances and replacing earlier forms of signals, including human flag men. This was important in the early days of railways because trains were either unbraked at first or until the development of much better fail safe air and vacuum systems, fitted with poor forms of brake that often led to disastrous crashes and death tolls.
You will note that the semaphore signals in this collage are both different. The one of the left in yellow with a chevron cut from and also painted on the end is called a distant signal and is near Hendra Station while the red signals (two arms) in the shot on the right are called home signals. The white cross on the top right signal means it is technically not in use, the crossing loop which it controlled in Ascot station is disconnected. The bottom signal controls the single track that remains that runs through the platform.
The yellow distant signal is intended as a warning to drivers about the position of the next home signal. They do not stop at distant signals. If the distant is showing stop (signal arm horizontal) then it tells them to be prepared to stop as the next home signal will also be showing red or at danger. They must never pass a home signal at danger or the "on" position. If the distant is showing proceed in either lower quadrant ( as these signals are - that is the arm falls if it is "off" or in the proceed position) or upper quadrant where the arm is raised halfway between horizontal and vertical (UK practice) or near vertical (US practice), then they know the following home should be showing proceed and they can expect to pass it without hindrance.
You will note that all these signals have two glasses on the inside end, red and green behind which sits a light which is used in hours of darkness. They were once fuelled by paraffin or kerosene but modern versions like these are electric. Semaphore Signals were mostly controlled by trained signalmen from signal boxes or other staff from small ground frames. They are designed to fail safe.
Passing a signal at danger, in modern terms known as a SPAD (or signal passed at danger) would be a situation subject to compulsory reporting and investigation leading to severe consequences and possibly termination. Signals at danger mean that there is another train or obstruction ahead. Many drivers have paid with their lives over the history of railways having caused a crash, often with fatal consequences for passengers and staff in both trains as well. The history of safe working improvements and their causes fills many books and is often littered with great drama, death and innovation.
Modern railway safe working is often carried out by computer systems, colour lights of course, in cab signalling, radio and fully automated systems that allow trains to operate without drivers. These can be found in places carrying passengers like the Tube and Docklands Light Railway in London or in Western Australia where Rio Tinto operates massive iron ore trains without drivers from a single control centre hundreds of kilometres away.
Please note that this is a very simple explanation of semaphore signal systems, which even though many years old and outdated now could be very complex in their operation on busy lines and junctions.
The last semaphores.
The last semaphore signals that I am aware of on Queensland Rail in the Brisbane area are on the single track Pinkenba line between Hendra and Ascot stations. They no longer operate, at least as far as I know as the line is also fitted with colour light signals.
Electric passenger services on this line terminate at Doomben station.
Semaphore signals were developed in the 19th century as an improved means of safe working on the railways, keeping trains separated by safe distances and replacing earlier forms of signals, including human flag men. This was important in the early days of railways because trains were either unbraked at first or until the development of much better fail safe air and vacuum systems, fitted with poor forms of brake that often led to disastrous crashes and death tolls.
You will note that the semaphore signals in this collage are both different. The one of the left in yellow with a chevron cut from and also painted on the end is called a distant signal and is near Hendra Station while the red signals (two arms) in the shot on the right are called home signals. The white cross on the top right signal means it is technically not in use, the crossing loop which it controlled in Ascot station is disconnected. The bottom signal controls the single track that remains that runs through the platform.
The yellow distant signal is intended as a warning to drivers about the position of the next home signal. They do not stop at distant signals. If the distant is showing stop (signal arm horizontal) then it tells them to be prepared to stop as the next home signal will also be showing red or at danger. They must never pass a home signal at danger or the "on" position. If the distant is showing proceed in either lower quadrant ( as these signals are - that is the arm falls if it is "off" or in the proceed position) or upper quadrant where the arm is raised halfway between horizontal and vertical (UK practice) or near vertical (US practice), then they know the following home should be showing proceed and they can expect to pass it without hindrance.
You will note that all these signals have two glasses on the inside end, red and green behind which sits a light which is used in hours of darkness. They were once fuelled by paraffin or kerosene but modern versions like these are electric. Semaphore Signals were mostly controlled by trained signalmen from signal boxes or other staff from small ground frames. They are designed to fail safe.
Passing a signal at danger, in modern terms known as a SPAD (or signal passed at danger) would be a situation subject to compulsory reporting and investigation leading to severe consequences and possibly termination. Signals at danger mean that there is another train or obstruction ahead. Many drivers have paid with their lives over the history of railways having caused a crash, often with fatal consequences for passengers and staff in both trains as well. The history of safe working improvements and their causes fills many books and is often littered with great drama, death and innovation.
Modern railway safe working is often carried out by computer systems, colour lights of course, in cab signalling, radio and fully automated systems that allow trains to operate without drivers. These can be found in places carrying passengers like the Tube and Docklands Light Railway in London or in Western Australia where Rio Tinto operates massive iron ore trains without drivers from a single control centre hundreds of kilometres away.
Please note that this is a very simple explanation of semaphore signal systems, which even though many years old and outdated now could be very complex in their operation on busy lines and junctions.