Eurotunnel: Enhancing communications beneath the seafloor

Karl W4KRL W4KRL at
Sun May 6 10:39:14 CDT 2012


May 6th marks the 18th anniversary of one of the engineering wonders of the
modern age. At 50.4km, the Channel Tunnel is the longest undersea tunnel in
the world, reaching depths of up to 75m below sea level. On an average, more
than 49,000 people pass through the twin tunnels between France and England
each day, with headways between trains often as short as three minutes at
peak times.

After almost two decades of intensive service, Eurotunnel is investing in
asset renewal to ensure this vital piece of infrastructure remains safe and
reliable. A key focus of this programme is the renewal of the
telecommunications network, which dates from the opening of the tunnel. At
the time of construction, Eurotunnel chose to adopt proven analogue
technology in an effort to optimise availability. The system is composed of
two elements:

.         A limited-capacity 3RP concession radio network for general
communications through the two running tunnels and the service tunnel

.         A track-to-train system based on contemporary British Rail
standards, for communication between train drivers and the control centres,
used only in the running tunnels

Eurotunnel Shuttle trains are equipped with cab radios for communication
through both concession radio and track-to-train, while Eurostar trains and
locomotives used on freight trains are fitted with International Train Radio
(ITR), a specially-developed cab radio that allows drivers to communicate on
British, French, and Eurotunnel systems.


"The business case for GSM-R was very straightforward because this is the
European standard telecoms system for railways and it gave us
interoperability with national networks," explains Keefe. 



The infrastructure is made up of active components (optical repeaters every
750m) and passive elements (transmission cables, fibre optics). Radio
coverage in the running tunnels will be provided by 750m-long sections of
radiating cable. The radio signal will be transmitted to the radiating cable
by optical repeaters and fibre-optic cable installed in the service tunnel,
minimising the number of base stations, and bringing down both the overall
cost of installing and operating the network. Installation is now underway,
with work being carried out in scheduled six-hour overnight maintenance
slots at weekends.

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