The kit preserving electric-powered wires above the song within the four-mile (6km) tunnel fails due to the salty situations below the Severn Estuary.
Network Rail has spent three years and what’s concept to be near £20m to put together the tunnel for electrification.
Specialists in electric rail had been delivered in to assist remedy the problem.
The UK Department for Transport has said it’s far “privy to an issue inside the Severn Tunnel works” and insists Network Rail is presently “carrying out investigations to remedy this as speedy as viable”.
Network Rail’s leader working officer Alison Thompson said she is “confident” the primary electric-powered will run between Cardiff and London early in 2020 – after production and testing takes vicinity q4 and over Christmas and new year.
The line is already electrified among London Paddington and Bristol Parkway.
The 133-year-old tunnel between Wales and England has its very own pumping station, which brings out an expected 14 million gallons of water (sixty-four million liters) a day to save you being flooded by way of an underwater spring.
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Network Rail conceded its miles a “tough operating surroundings to run 25 kilovolts of electrical through”; however, insisted trips will now not be affected because the new multi-million trains that serve the direction are diesel and electric hybrids.
Trains journeying into and out of the tunnel could be powered by way of the overhead wires. Still, they will transfer to diesel to tour under the Severn Estuary – so passengers interior will not realize the distinction.
Stuart Cole, emeritus professor of shipping at the University of South Wales, defined the salty situations have been more of trouble because the tunnel is not within the outdoors.
He introduced that switching to diesel within the tunnel isn’t always a massive hassle, given the period of a few passengers’ journeys.
“It’s no longer the give up of the sector if they don’t find a answer, but the chances are they may,” he instructed BBC Radio Wales.
Electrification of the South Wales line was supposed to be finished utilizing this 12 months; however, Network ‘snail’s final year said it could not give a particular date because paintings remain ongoing.
The difficulties are today’s blow to the task, after delays, teething issues for the new trains, and the selection to scrap electrification of the road from Cardiff to Swansea.
Former Prime Minister David Cameron introduced the electrification of the Great Western line in 2012, and the tunnel changed into the close for six weeks in 2016 to begin the electrification venture.
But in 2018, the then UK delivery minister Jo Johnson admitted that electrification devices in the tunnel had begun to go to pot.
Earth straps – a protection function at the overhead connectors maintaining up the energy line – have been eroding inside the saltwater environment within months when they’re alleged to have a 25-12 months lifespan, which means the line thru the tunnel could not be electrified competently.
It means the electrification machine within the brickwork tunnel – the longest underwater tunnel within the world for greater than 100 years after it opened in 1886 – struggles to preserve voltage and frequently trips.
Network Rail shriveled experts from Swiss enterprise Furrer and Frey, specialists in developing strength cables inner tunnels, in designing a solution; however, none have labored inside the salty weather.
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Engineers need to affect the line to carry the new bi-mode Hitachi trains – a part of the United Kingdom government’s £5.7bn educate fleet – which entered the carrier in 2017.
“The new intercity electric-powered trains function in both diesel and electric powered,” said a Network Rail assertion.
“Their operation via the tunnel isn’t affected, and we are on course to introduce the new better timetable in December 2019 that is the result of the modernization and electrification over the last few years.
“The timetable will deliver large blessings to passengers in south Wales, with reduced adventure instances of up to 14 mins to London and considerably improved capacity.”
Franchise holders GWR may be operating electric-powered trains thru the tunnel and say they’re “conscious” of Network Rail’s upgrade. However, they insist the works remain on track to introduce their advanced timetable in December.
The Welsh Government said Network Rail had confidence them the problem could not affect passengers.
