Dawlish blockage 21/6/2024... Important transport link shows vulnerability again!

[stuu]

Although an agree with the majority of what you’re saying, I think a handful is a fairly major exaggeration. You just have to look at GWR’s network to see that. Between Reading and Taunton, Newport and Worcester the majority of long distance route have diversionary routes, and the same goes for the ‘middle’ section of a lot of long distance routes.

However these diversionary routes all exist on the basis that they are justified routes with services running anyways. The railway is already being deemed to cost too much money, we cannot build empty routes and maintain them just to use every now and then.

As an aside, on the proposals from this thread on reopening the line from Okehampton, regardless of already mentioned bridge issues, using it for diversion would be totally impractical, because of both the double reversal at Exeter and Plymouth, but also because I am totally unconvinced an IET could be cleared, especially if it linked with the Gunislake branch, which already has issues with coach length around the bends on a 150.

The issues with clearance are all on the branch, the main route was all double track so there wouldn't be any insurmountable problem.

Apart from it's completely unnecessary of course. There's far better ways to spend £1bn on the railways in Devon than rebuilding Okehampton-Plymouth

 

[D869]

How many years has the Dawlish route got left? It will have to be replaced at some time. Anybody know the maximum gradients on the A380 south of the A38?

 

[swt_passenger]

How many years has the Dawlish route got left? It will have to be replaced at some time.

IIRC the Dawlish seawall rebuild had a design life of 100 years from 2020.

 

[Benjwri]

IIRC the Dawlish seawall rebuild had a design life of 100 years from 2020.

And regardless it would likely be able to be rebuilt again after that time. I really think people need to stop getting the crayons out. It is hugely unlikely the line will be moved in any of our lifetimes, the current wall will outlast most of us. I really thing anyone considering such suggestions should read the study from 2014 on the matter. You only have to read as far as page 5, the important table from which is quoted below:

Option	BCR
3 (Alternative Route A)	0.14
4 (Alternative Route B)	0.29
5 (Alternative Route C1)	0.08
5 (Alternative Route C2)	0.12
5 (Alternative Route C3)	0.13
5 (Alternative Route C4)	0.17
5 (Alternative Route C5)	0.15

Above is the proposals and their relative cost benefit ratios. Not a single one reaches 0.3, which is to put it simply abysmal. There are also further tests undertaken, such as reducing costs and having the sea wall route be closed for 40 days a year and it performs equally bad. The reality is that maintaining the sea wall, or even upgrading it further, is significantly cheaper than a new alignment (Except option 3, however this was judged to be even more prone to flooding than the sea wall), and as much as we all love new railways opening, there just isn't the case for it here.

 

[Irascible]

By this logic shouldn't the second route bypass the single point of failure of Exeter? That seems like it's just undermining it's own case.

Obviously the second route should be via Taunton-Barnstaple-Halwill-Tavistock! never mind the A361, it's a horrible road ( genuine opinion there, the 3 lane done on the cheap bit really is horrible ).

I'd be quite surprised if going through Launceston & Wadebridge was ever used for diversions, so Plymouth has always been a weak link for Cornwall. I've not been paying attention to how the flood prevention at Cowley Bridge has been getting on because I live the wrong side of Exeter these days, maybe one of the residents can chime in?

Hard to think of a catastrophe that could knock out the A38, the A30 and possibly even the A39 without taking out a hypothetical railway via Okehampton!

Or most of Devon! or, indeed both Tamar bridges.

How many years has the Dawlish route got left? It will have to be replaced at some time. Anybody know the maximum gradients on the A380 south of the A38?

The Dawlish wall will probably outlast Dawlish... if the bits either side eventually end up in avalanche shelters they'll probably last longer than the cliffs.