The rail line at Dawlish on the south Devon coast has been closed after the sea wall was breached.
Flooding and debris blocked the line after up to 15 metres of fencing and stones were displaced, Network Rail said.
A “substantial amount” of ballast has also been washed across the track along 150 metres of the railway.
Trains are unable to run along the route, which suffered severe damage after the sea wall collapsed during storms in 2014.
The railway runs along the coast in south Devon (Network Rail/PA)
A Network Rail spokesman said: “There is no structural damage to the sea wall, and the integrity of the railway itself has not been damaged, which is testimony to the quality of the strengthening works Network Rail delivered in 2014.”
No services will operate on the route on Friday.
Plymouth Sutton and Devonport Labour MP Luke Pollard described the closure of the line as “bad for our local economy” and accused the Government of making “vague promises of jam tomorrow” in the South West rail strategy.
He added: “No firm commitment to new money – simply not good enough.”
Transport Secretary Chris Grayling said on Wednesday that avoiding a repeat of the 2014 disruption at Dawlish “has been a key priority” since he began his role.
The Government has previously provided £15 million for Network Rail to design a “long-lasting solution to this problem” in addition to the £40 million spent by Network Rail to repair the damage caused four years ago.
Jon Shaw, transport expert and head of geography at the University of Plymouth, said: “The latest damage to the sea wall is a timely reminder to the Transport Secretary that work to improve the quality and resilience of our transport network here in the South West is of the highest priority.”