Great Western Coffee Shop

How long will the new Dawlish Sea Wall last?

Who can tell?   ;D  ;D.  Take a long read at http://www.firstgreatwestern.info/coffeeshop/index.php?topic=22771.0 and you'll get some idea of what's going on - idea is for a "permanent" solution but 60 years, 100 years, who knows?

The planning documents for the Marine Parade section reckoned a 100 year design life.

The drawings for the section just started, (Coastguards to Colonnade), also include a predicted mean high water level (MHWL) in 2115 of about 90 cm above the 2017 value.

Significant challenges today. (https://www.dawlishbeach.com/2021/02/trains-v-wind-waves-dawlish-11th-february-2021/)

A couple of Voyagers managed to negotiate the waves before XC stopped all services west of Exeter.  Three GWR IETs killed by sea water.

The report I saw suggests the Exeter to Plymouth IET quoted in the article was NOT hit by the sea but was running in “special mode” when it came to a stand.  Anyone know more?

Once on the move, after crossing back over at Teignmouth to the down line, it then ran empty to Laira.

Seemed not too bad after 4pm at Dawlish on the 11th Feb XC service I was on to Temple Meads.  It was an HST and the waves weren't too splashy.

Sea wall has been closed by Network Rail for safety.

from journeycheck (thanks to pymothian for the heads-up)
Alterations to services between Newton Abbot and Exeter St Davids
Due to the sea flooding the railway between Newton Abbot and Exeter St Davids all lines are closed.
Train services running through these stations will be delayed or revised. Some stations between Newton Abbot and Exeter St Davids will not be served. Disruption is expected until 11:00 12/02.
Further Information
An update will follow within the next 1 hour.
If you hold a valid single, return, or weekly ticket, you will be able to claim compensation for delays of 15 minutes or more. Please keep your ticket and visit GWR.com/DelayRepay
Last Updated:12/02/2021 07:54

When the new IET's were introduced, this was one of the first questions asked in this forum I believe.
The answer was the trials were good, and they were cleared to run.
Nature showed otherwise!

I note this closure is a Notwork Fail closure. so presume they pay the TOC's for lost running?

And as a P.S to my post above.
Those trains stopped shorted - how are passengers transferred to the onward connection?
Guess there are not too many passengers involved, but in journeycheck there is no mention of bustitution; guess it's all taxi transport.

First Travel Solutions has begun to source coaches.
1 Tamar Coaches coach is en route to Netwon Abbot currently.

Question:

Which section of the line has the problem?  Does it give hope that the improvement works will resolve or at least improve the problem?

Looking at the Dawlish cam about an hour after high tide this morning the wall was getting a good pasting and waves coming over the top but with less force and more spray that reached the cam lens.

I, and others predicted that the new units would fail to cope with the severe but well known conditions at Dawlish. I based my prediction not on any detailed technical analysis, but on the performance of other new trains such as voyagers, and on a cynical suspicion that new trains are often less reliable under adverse conditions.

Supporters of IETs felt that I was being unduly negative, and pointed out that coping with Dawlish conditions was an "essential requirement" written into the specification.
When the new trains failed to operate reliably under known adverse conditions, it was revealed that the "essential requirement" was in fact only a requirement for decorative finishes to survive, with no requirement that the trains actually work.

In addition to the problems between Dawlish and Teignmouth, there has now been an incident near Starcross.

The mast of a boat being battered in the harbour has damaged a railway signal so access to Dawlish Warren from the Exeter end is now cut off.

Where on earth did you get that from? It falls in the technical category known as "bollocks".

This is from Rail Magazine (https://www.railmagazine.com/news/network/from-the-archives-how-the-class-802s-will-avoid-the-fate-of-voyagers-on-the-devon-sea-wall) (HRE is Hitachi Rail Europe):

Basically, Hitachi screwed up. Not the only example, either. And note that 800s are better off than 802s, not having brake resistors on the roof. They just weren't intended to go past Exeter, though required to be able to do so.

I got it from a respected member of this forum, who stated on this forum that the "essential requirement" refered to decorative finishes and not to functioning.

Something wrong at Dawlish? Wrong road running, trains cancelled two hours before high tide.

As bobm said, a signal has sustained damage and is in danger of being hit by trains at Starcross.

From Journeycheck

How much sea level rise has there been in the 150 or whatever years since the railway was built? How were Victorian railways expected to cope with this section? Or was it simply accepted that they wouldn't run in bad weather?

"Special Mode" is initiated by the driver through the train management system.  It has only been bought in recently following previous failures of IET's on the seawall.  "special mode" was Hitachi's answer to those previous failures, all it enables is several more attempts at restarting failed engines before they eventually lock themselves out of use. 

Normally you can restart the engines and leave them in a idle state which effectively dries out the engine.  If you put any load through the engine too soon it just shuts down again thats why they can normally resume working after a period of time.

Presumably - stoke up the firebox, close the firebox door as you approach Dawlish, pull your coats up over your ears and press on for Teignmouth!

I don't know of any steam locomotive that ever had a brake resistor mounted on its roof. 

Remember Brunel's original intention was to use the Atmospheric system along the sea wall.

They had no brake resistors either!

And neither steam locomotives nor the atmospheric railway had computers that under adverse conditions tend to stop everything and may not even allow re-starting.
A significant number of IET failures have been "computer says no" rather than a physical component breaking, catching fire or dropping of.

Some time ago I found a technical paper that described numerous failures and closures of the sea wall.  Serious damage had reportedly occurred every 10 years or so ever since opening.

https://www.sciencedirect.com/science/article/pii/S2212420921000480?via%3Dihub

Although the 2014 closure was spectacular and probably the longest unplanned closure, it’s definitely not the case that all was well between first opening and recent times.  Brunel’s original wall past Dawlish didn’t last very long and was completely rebuilt at one stage.

I used to live in a block of flats in Plymouth City centre. Also in the block were a Mr and Mrs Downton. They had lived there since the blocks had been built in 1953. He was a fireman and later drive for the Southern Region based at Friary initially.

He recounted a story to me, about a time during the exchange WR/SR workings that going along the Wall, a large wave crashed down on their locomotive extinguishing the fire and drenching them!

I have no reason to disbelieve him and never asked if it were possible. We had been talking about the voyagers dislike of salt water, that the IETs seem to have as well.

Seems that the problems have always been there, just in different guises

It seems unlikely, but just about possible that a freak wave would extinguish the fire in a steam locomotive.
Most of the fire is somwhat enclosed and protected against waves. There are only three routes by which significant water could enter.
Down the chimney, only a limited opening, and most of the water would pool in the smokebox rather than pass through the tubes and into the fire.
Via fire box door, possible especialy if the door was left open to warm and dry the crew after the previous soaking.
Up wards via the ashpan, unlikely unless there was standing water up to that level.

So unlikely, but just about possible in truly extreme conditions. Or of course the fire might not have gone completly out, but been discouraged to the extent that steam pressure was lost.
Any water entering via the chimney would probably evaporate before reaching the fire, but in so doing would absorb a lot of heat from the boiler and reduce the steam pressure.
Coal in the tender that was soaked by a wave would still burn but less effectively than dry coal.

Potentially dangerous for the driver and fireman I’d have thought.

But that's only the latest, model-specific problem. There have been problems with waves and high water encroaching the tracks there for much longer. I remember reading about flooding problems there in the 1990s.

The east-facing section of Devon coast from the Exe estuary south to Start Point has always faced a battle with the elements, which it invariably loses. Anyone wanting to understand this should read the history of Hallsands, where the original village was completely wiped out by a succession of storms during the first years of the 20th century, with waves sometimes breaking right over its houses. Eventually the last buildings were lost in 1917, and a new village built inland. That village is now on the coast, and will face the same battles.

Yes, two main risks IMO, firstly the very sudden cooling of parts of a hot boiler might cause an explosion due to unequal stresses. (note that steam ships often explode if they sink, as sea water contacts hot boilers)
Also risk of burns from sudden clouds of steam, steam is far more dangerous than hot air, since it condenses on the skin and gives up latent heat.

Possibly a slight risk of hypothermia if the train was unable to proceed, and the crew were exposed to cold wet conditions without the heat from the fire.

Agree with this. Slapton Sands A379 is again under threat and may not be rebuilt if it goes again.

Hollicombe Beach between Torquay and Paignton is another risk that if it went would be very difficult to repair. Nearby cliffs by Institute beach are being hollowed out by the sea and I wonder how secure Cliff Court apartments are.

Should be OK as long as they can swim.

Swimming doesn't really work unless the water sits still, with a flat top and air above it!

And I think that's the key to what could have happened. We've seen the "spray" coming over the old sea wall, which goes up the wall and slightly forwards and comes down onto the track. And it contains some big lumps of just water, not mixed with much air, and capable of piling up quite deep. Of course it immediately starts responding to gravity by falling to the ground, tending towards the lowest and flattest it can.

So, could it - briefly - either sit there and have a train drive through it, or force its way in from the side, deep enough to force its way through the air damper to the underside of the grate? It's very hard to imagine - this kind of dynamic behaviour of water just doesn't match our intuition, mainly because it's hard to experience or even observe closely enough to understand it. But I suspect it is possible - perhaps not likely, but then that wasn't the question: it was reported as happening just once.

Hallsands was also done no favours by the extensive dredging of the seabed immediately offshore that was used in the construction of the Plymouth breakwater.  It wasn't long before the shingle beach started to recede which left the village without it's former protection from the forces of the sea.
Nowadays, it is indeed a strange place to visit but you can still make out the remains of houses, once lying flush with a shingle beach, now perched on rocks.

Correction....not the Plymouth Breakwater, but the North Extension to Devonport Dockyard (1896-1906).