Combining Radar Sensor and Data Transmission between Vehicles in Tunnels

An equipment combining data transmission between two trains running in a tunnel, while simultaneously measuring the distance between them, could be very attractive for improving both efficiency and safety of the transportation system. After recalling the main propagation characteristics in a tunnel, a system based on the exchange of pseudo random sequences is briefly described. Extensive measurements took place in various environments. Tests in subway tunnels are emphasized, since this corresponds to a complicated geometry, the tunnel presenting many curves and changes of its cross section.