Engineering news
Interference from 4G mobile phones could delay and add cost to a new wireless signalling system that will be an essential part of railway lines such as High-Speed 2 and Crossrail.
The European Railway Train Management System (ERTMS) is being introduced throughout Europe to increase the capacity of railway lines by up to 40% and make cross-border travel simpler. However, because the frequencies that the new system uses are adjacent to the ones allocated to public mobile-phone networks, interference can occur.
Compounding the problem is the introduction of high data rate 4G mobile-phone networks in the UK and Europe, which experts predict will cause even more interference. The wireless signalling uses a global standard for railway voice and data communications called GSM-R, which is based on the public GSM technology.
Jacqui McLaughlin, president of Smiths company Kaelus, which has developed a radio frequency filter that cleans up GSM-R signals, said the problem was similar to the issues with 4G and digital television. She said: “The advent of 4G means it is much more likely mobile-phone networks will cause interference with GSM-R.
“The fear is that the combination of the increased use of 4G and the move to high-speed trains will create a tsunami of events and problems for European railways. Experts throughout Europe have come to the consensus that we need a solution.”
At least 15 European countries that have already introduced the wireless signalling technology have identified areas of track which suffer from interference. European Commission documents that detail investigations into the issue seen by PE state that high-speed trains in the Netherlands and Belgium have had to be stopped because of communication black spots. The Dutch government is investigating the problem following a recent round of 4G licence issues.
The wireless signalling technology, which is specified for all new trains and track following agreements made in Europe, will be an integral part of future high-speed train operations and capacity improvements over the next decade in the UK.
Left unresolved, the interference issue could restrict the introduction of signalling techniques that will significantly improve speed and capacity on railway lines.
Network Rail, which is tasked with introducing the GSM-R wireless technology and ERTMS in the UK’s rail infrastructure, said it was aware of the problem and had experts working on a solution. GSM-R technology is halfway through its installation in the UK. ERTMS has been trialled on the Cambrian Line in Wales, and testing will start on a five-mile section of the Hertford loop this summer.
Network Rail said: “We’re working closely with stakeholders across Europe to understand the characteristics and the effects of mobile networks on the GSM-R train mobile.
“Radio frequency filters are one approach to protecting GSM-R from interference, which could be applicable in some countries, but this is a Europe-wide project involving multiple operators, regulators, telecoms companies and railways, and there is no one-size-fits-all solution.”
Other possible solutions include tweaking of mobile signal base stations, the use of signal repeaters alongside track which suffers from interference, or the switching of GSM-R to a different bandwidth.
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