The Channel Tunnel last week celebrated the 20th anniversary of the first services running through its 50km long twin running bores.
French transport minister Frédéric Cuvillier led the celebrations in Coquelles at the Calais end of the tunnel. These included the unveiling of a plaque and commemorative stamp design.
Deemed the most significant major building project of the last 100 years by the International Federation of Consulting Engineers after beating off competition from Japan’s Shinkansen bullet train and the Sydney Harbour Bridge, the tunnel is also making its mark as an evolving piece of infrastructure.
Eurotunnel revealed last week that it had installed British mobile telephone services inside the north running tunnel, enabling passengers heading for France on Le Shuttle and Eurostar trains to make calls and use the internet. This has been possible in the south tunnel since mobile phone access was installed ahead of the 2012 Olympic Games.
Tunnel operator Eurotunnel said providing these services 100m below sea level, in the longest submarine tunnel in the world, was “a feat unequalled in the world today”.
“In the constant search for improvement and enrichment of services provided for customers, Eurotunnel has continued to invest throughout the past 20 years to modernise its transport system and to respond to the ever increasing communications needs of its passengers,” it added.
Amid the financial challenges - the firm announced it had begun making profits for the first time two years ago - the tunnel continues to be enhanced and altered.
The scale of the maintenance work involved on such a heavily used and hard to access piece of infrastructure was highlighted earlier this year. Then, re-railing work was halted temporarily because of a carbon monoxide scare among 30 workers (NCE 6 February).
Re-railing work in the tunnel is almost continuous. Up to 300 trains travel the route each day at speeds up to 250km/h, often with heavy loads. The 100km of rails have to be replaced every eight years in maintenance slots overnight at weekends.
Eurotunnel is developing new longer lasting steel alloy rails with research body i-Trans. These will be installed at the next change of rails. This next generation track will last 20% longer than their predecessors and they will be able to carry 1bn.t of traffic before being replaced. At present track has to be replaced after 850,000t of traffic has passed over it.
More than 20,000 detectors are installed in the tunnel to ensure safe conditions for workers and the public. Safety issues and cost concerns were at the root of the operator’s decision a few years ago to finally install a fire suppression system along the length of the running tunnels.
A third fire in September 2008 caused the second major closure of the tunnel since it came into service, on this occasion for five months while serious damage to the concrete lining on a 650m stretch of one of the running tunnels was repaired.
As a result, the firm opted to install a Fogtec sprinkler system comprising four approximately 800m long stations - two in each of the running tunnels around a third of the way from each portal.
Fibre optic cables pinpoint fires within individual wagons, before water mist nozzles are activated in the critical areas. It produces a mist of very small water droplets that can cool air temperatures in a burning tunnel from 1,200˚C down to 50˚C in two minutes.
Fogtec designed, built and installed the system with Eurotunnel engineers.
In the 20 years since its inauguration 330M people have passed through the tunnel and around €700M (£570M) has been invested in the link.