11 April 2017

More than 300 trains a day now pass under the Swiss Alps at 155mph – and passengers have 4G mobile coverage all the way.

The Gotthard Base Tunnel is 35 miles long and took 16 years to construct at a cost of £8.2bn. It means that a Lugano-Zurich journey now takes two hours, cutting 45 minutes off the time taken in the old rail tunnel which opened in 1882.

Named after an 11th century bishop, the new tunnel is the world’s longest and, at a maximum of 1.5 miles, the deepest of its type. Its twin bores were cut with four machines – named Sissi, Heidi and Gabi I and Gabi II – each nearly the length of six London buses (1,400 feet).

Mobile communication in the tunnel is through a distributed antenna system (DAS), designed and commissioned by CommScope.

The challenge was to support a number of different networks: the railway’s GSM-R system for train drivers, dispatchers and on-board staff; two public GSM networks; a UMTS network; and a PMR public safety network. In addition, the system supports LTE public traffic.

CommScope says it decided to assign the higher reliability GSM-R and PMR networks to a main system while the others would be supported by a parallel system. It installed a DAS called ION-M which has 31 master control units – 17 on the main system and 14 on the parallel system – connected to nearly 700 remote repeaters.

The signals from the repeaters are distributed throughout the main and access tunnels by 93 miles of Radiax radiating cable made by Andrew, a company bought by CommScope in 2007.

Fixed network equipment was supplied by Alcatel-Lucent (now part of Nokia) and installed by Zurich-based Alpiq InTec. It has been in use since tunnelling began and now features 450 of Alcatel’s OmniSwitch 6855 Ethernet switches as part of a LAN to control tunnel lights, racks, power systems, doors, drainage and ventilation.

In addition, they connect the video surveillance systems to control centres at each end of the tunnel.

Alcatel says the switches were chosen because of their reliability in rugged conditions: temperatures in the tunnel can reach 40ºC while humidity can hit 70 per cent. Maintenance therefore needs to be minimal.

The network is controlled by two of the company’s OmniVista network management systems.