Protecting a one-mile stretch of coastal railway from crumbling cliffs could cost £250million.
Engineers want to move the track closer to the sea and away from the cliffs while also building a sea wall.
The line near Teignmouth in south Devon is under threat from rising sea levels, landslides and erosion.
It had to be shut for six weeks in 2014 after 20,000 tons of stone and earth crashed on to the line.
The same storm swept away much of the sea wall and tracks near Dawlish three miles north.
The closure of the Great Western Railway cost the economy in Devon and Cornwall an estimated £1billion.
The line was rebuilt by Network Rail engineers at a cost of £35million.
Now they are proposing the £250million scheme to shield the track between Teignmouth and Parsons Tunnel, near Holcombe.
New cycling and walking routes will be built to enable the public visiting Holcombe beach can enjoy the view of the coastline.
Officials insist the work will last for at least another century and protect against expected higher sea levels.
Earlier this year Transport Secretary Chris Grayling earmarked up to £80million to build a sea wall to protect the tracks from storms and rising sea levels.
Work began at the beginning of the month, with the project not due to be finished until January next year.
Construction will pause from July 14 to September 9 to avoid causing disruption for passengers visiting Devon and Cornwall during the summer holidays.
The main line from London Paddington to Penzance travels along the coast, making it particularly vulnerable to the weather.
Campaigners have long argued that the money would be better spent on reinstating the London and South Western Railway further inland.
Taking in Okehampton and Tavistock, this section was closed as part of the Beeching cuts in the 1960s.
Network Rail officials claim this would be around six times more expensive than repairing the line along the south Devon coast, and better shielding it from the elements.
Network Rail has launched a five-week public consultation on the plans, in which local residents, passengers and businesses will be able to express their views.
It will publish updated proposals in the autumn.
Network Rail said the design would require some land reclamation to allow for the construction of a buttress – a sloping rock structure to stabilise cliffs and protect the railway.