http://www.bbc.co.uk/news/uk-england-devon-26874503
(if you go to the bottom of that link you will see that the BBC is asking for comments etc from those who live here/use the line).
Go Dawlish Go!
Ref above BBC: Andy Crowley, from contractor Amco, said: "The amount of concrete that's gone in there, that will be there for at least 200 years, beyond a shadow of a doubt." I guess that the 4-10year comment on the 'One Show' must therefore refer to the rest of the 4miles. Hence the breakwater being mooted.