A new wall is to built to protect a railway line that washed into the sea in 2014.
Up to £80 million of Government funding will be made available for the project in Dawlish, Devon.
The structure will be 2.5 metres higher than the existing five-metre wall to increase protection to the railway from waves during adverse weather.
Construction is expected to begin in the spring and completed by 2021.
Public sector company Network Rail spent £40 million to repair the track following devastating storms five years ago.
The line, which is used by Great Western Railway and CrossCountry, has since proven susceptible to flooding, forcing services to be suspended on multiple occasions.
Transport Secretary Chris Grayling said: "We cannot allow the disruption and damage endured by Dawlish and the South West to happen again.
"This significant investment demonstrates our cast-iron commitment to delivering a resilient and safe railway, giving passengers, businesses and residents confidence in a reliable service.
"With up to £80million of funding available to create a rigorous set of defences, this new sea wall will help protect this vital route, building on our ambitious plans to grow this region's economy and prosperity through stronger transport connections."
The project is part of a £2 billion Government investment to support growth in the South West.
The news was welcomed by Dawlish resident Julie Yates, whose home will be behind the sea wall.
I think it's a good thing if it's going to protect the road and protect the houses on this side because in 2014 it was horrendous. I lost my other car - that was written off - and the water came right up to the flats.
There was relief in Dawlish today that work will be starting on the section of sea wall by the station but much more is needed to protect the railway line and the town each side of the stretch.
A sea wall needs to be built on the north side of the station and in the cliffs south of the town, the track needs to be moved and perhaps even a tunnel built.
It's a much more complex piece of work. It involves moving the railway away from the cliffs - that's our early thought about what we will need to do - but it is in early development. We've got several options we need to explore and what's really important to us is engaging the local community.
All this will require much more investment.