To me, it seems that the way to proceed should be:
1) repair the wall & strengthen further if possible =>
2) reinstate Okehampton-Tavistock-Bere Alston, not just to provide a diversionary route when needed but also to reconnect Okehampton and Tavistock to the network and provide a railhead for North Cornwall & West Devon. =>
3) Plan for a Dawlish Avoiding Line to ensure that if/when the sea wall gives up the ghost, the South Devon & Torbay route is retained as well.
All for 500,000 people? Hmmm. Maybe a selection of 2 out of 3. Unless they can access
EU» money for the other
Maybe I need to clarify my reasoning. I'm trying to look at a bigger picture than just the sea wall.
In the short term, the wall is going to be repaired (point 1), meaning that we're back to where we were before the storms, hopefully with slightly more robust sea defences in place.
We also have a line from Plymouth to Bere Alston which, it seems, is going to be extended to Tavistock in the next few years. The line from Exeter to Okehampton/Meldon also exists, albeit without a regular passenger service, though there has been talk of reinstating one in conjunction with developments in/near Okehampton.
By joining up these two "ends", you have an orbital line linking Tavistock and Okehampton to Plymouth, South Devon and Exeter as well as a railhead for the swathe of North Cornwall & West Devon that was amputated from the national network in the 1960s. If this were to happen, the Yeoford-Crediton-Exeter stretch of the Barnstaple line would benefit from more trains, thus reducing congestion, one would hope. Oh... and a diversionary route.
However, I don't believe that this line could replace the South Devon route, which serves the population centres and tourist destinations on the English Riviera, on anything other than a diversionary basis, so
if the sea wall line must go completely, then it seems imperative to plan (3) for a Dawlish Avoiding line. I'm not suggesting that such a line should be built in parallel with a reinstatement of the Okehampton route but that it should be planned for in anticipation of the time when the sea wall route is on borrowed time.
Thus, while the sea wall holds up, we'd have a main and a diversionary route and if it doesn't, we'd have the Dawlish Avoiding line providing a main route and a secondary (diversionary during engineering works) route. By going directly for the Dawlish Avoiding line, it's true that we'd solve the sea wall problem but we'd still not have a diversionary route.
