Jack Loughran Thu 26 Mar 2026
Collected at: https://eandt.theiet.org/2026/03/26/quantum-navigation-system-fitted-london-train-offers-alternative-unreliable-gps
Network Rail is introducing quantum navigation technologies that can measure the position of trains with extreme precision.
The location of trains on the network is typically determined using an electric track circuit that runs a current from one rail to the other through a relay. When a train runs on a section, it causes the current to bypass the relay, which is picked up by the signalling network. This is also supplemented by various technologies, including GPS and automatic warning systems that can monitor the exact position of carriages.
But these technologies are vulnerable to a number of faults that can cause major delays including broken rails, a blown fuse, faulty electrical parts, cable theft or loose connections, all of which form a break in the track circuit.
Network Rail is trialling quantum inertial navigation, which uses ultra-sensitive sensors capable of detecting minute changes in motion and rotation. This means that as long as the initial position of the sensor is tracked, the data collected can make an approximation of location without ever having to send or receive a signal remotely.
National Rail
Unlike satellite-based navigation systems such as GPS, it does not rely on external signals, meaning it could provide highly resilient positioning even in environments where satellite signals are unavailable, such as tunnels, dense infrastructure or areas affected by interference.
The technology offers a potential future alternative to fixed trackside positioning infrastructure, which can be costly to install and maintain and is vulnerable to environmental disruption or equipment failures.
The trial saw the installation of a rail quantum inertial navigation system (RQINS) on a Great Northern train operated by Govia Thameslink Railway between central London and Welwyn Garden City. The demonstrator provided real-world data on how quantum positioning technologies perform within the railway network environment.
Last year, a similar system was trialled in the Arctic in collaboration with the Royal Navy that could provide information about a vessel’s location that is impervious to GPS spoofing from hostile forces.
Rail minister Lord Peter Hendy said: “For more than two centuries Britain’s railway has forged technologies that have shaped the modern world. The development of quantum inertial navigation continues that legacy. With these new capabilities, we’re preventing equipment failures, helping to boost our railway’s reliability and keeping passengers moving.”
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