The world's longest... and deepest... railway tunnel is the Gotthard Base Tunnel in Switzerland which runs 35.5 miles (57 km) with as much as 2,300 meters of rock cover.
More than 17 years were required to construct the tunnel and there were numerous challenges involved that included how to get PMR (Private Mobile Radio), GSM-R (Global System for Mobile Communications – Railway) and UMTS (Universal Mobile Telecommunications System) to operate within the tunnel. Communications services are required for workers, train operatives and passengers in order for them to use their mobile phones for cellular phone calls/text messaging and 3G/4G mobile data.
In order for the GSM-R, PMR and UMTS base stations to operate, they need to be provided with timing synchronization. Digital services provider, ATOS AG needed to get GPS signals from an outside, clear sky location into the tunnel to the base stations. ATOS solved the challenge by using specialists ViaLite Communications’ RF over fiber GPS links. These high sensitivity links allow the signal, which is very low at -110 to -130dBm, to be accurately transported over considerable distances; connecting high-gain ViaLite GPS antennas—located on the mountainside—to the base stations within the tunnel.
The ViaLite system used incorporates 3U rack chassis units and multiple levels of 1:1 redundancy to ensure 5 nines reliability; this is very similar to the ViaLite system in the London Underground which was installed in 2001/2. Gotthard Base Tunnel’s system also incorporates ViaLite ODE-A outdoor enclosures, which are used to house the GPS links above the tunnel; protecting them from the elements.
ViaLite Communications provided full on-site training to ATOS to allow them to install and service the GPS links in Switzerland, where the tunnel connects Ersfeld (UR) and Bodio (TI). The Gotthard Tunnel opens for full service on December 11, 2016.