If you live in or around a big city like Sydney or Melbourne, you will have traveled by train at some point in time. Most people would understand the basic concepts, like the signal is at green, the train arrives turning the signal red for a short period of time until the first train has moved a safe distance away, allowing the signal to turn green again. There are signals located in every sector, where trains travel through and they are very reliable; should the signalling system fail, then all the trains stop and you have a right side failure. When the signalling system is no longer operating correctly or if it has received conflicting data from track circuits, all the signals display a red signal and the driver needs to be authorized by the signaller to pass.
The driver after waiting for a short period of time, contacts the signaller using a train radio for permission to pass a signal at red. The train radio is used for mission critical communications, because passing a signal at red can cause an accident, such as one train crashing into the back of another or head on collision if at a siding entering a main line.
The origins of modern train radio go back 40 years to 1977 when a paper written by Clive Kessell on “The Development of Radio Communications between the Signal man and the Driver” was presented at an Institute of Railways Signalling Engineers meeting to promote interest in developing radio communication between train and the signal box. Radio communications was the best way to stop a train or move one that had stopped; it is safer to keep the driver in the train rather than walking the track looking for a signal post phone to contact the signaller.
A communication standard was developed at the time called UIC751-3 created a 4 channel UHF analogue train radio network that was deployed around London’s Kings Cross and St Pancreas station; it was also rolled out in parts of Europe, especially in West German where much of the initial development occurred.
The analogue train radio Metronet was rolled out in Sydney in 1994 at the same time a very similar radio system called “Cab Secure Radio” was deployed in the UK and other parts of the world. In early 2000 a newer radio network was developed based in Europe on the popular GSM standard, moving away from an analogues network to digital voice improved the voice quality, reducing the unwanted static that analogue communication was famous for. This digital train radio system (DTRS) was commissioned in 2017 in Sydney to replace the analogue Metronet and improve rail communications.
However the pace of change by mobile phone utilities occurred quickly, GSM (a second generation technology) which DTRS is based on is now almost obsolete; we have all come to love the benefits of advanced 4th generation mobile phone technology. In the railway sector, there is considerable interest in what technology will be used to replace DTRS, how it will be developed and when it will be implemented.
My research looks at these issues to identify how a modem broadband 4th generation mobile technology can be developed to provide all the mission critical communication needed to operate trains along with the benefits that high speed broadband data can deliver like real time CCTV. The risk adverse nature of railways consider any change as an increase in risk, so they have become change adverse in the process. However by keeping old technology, risk increases because the safety benefits associated with newer ways to communicate are not realized; there is also the technical challenges in keeping equipment that is not supported operational when replacement hardware components cannot be found.
Running a modern railways such as the one in Sydney, where you have a million passenger journeys a day really requires a modern communication system so safety is not compromised. The signalling system is reported to have a wrong side failure once in thousands of years but yet they happen for reasons no one every considered.
The train radio allows corrective action to happen immediately by the driver and signaller to prevent an accident from occurring; saving many people from serious injury or death if you have a train crash. Fourth generation mobile communication are now a proven technology that can provide the mission critical communication allowing GSM-R to be retired sooner rather than later.
Link source Tech