Suggestions for solving Dawlish problem: electrification or new route?

[Master29]

How observant!

(This is a Web Forum - it is not Planning Central of Network Rail or the DfT. What on earth are you expecting?)

You`d think so given some of the replies. Consultants R us.

 

[ScottGallagher]

Back when the line was built, was the sea as violent as it is now? Makes you wonder how they ever built it and why it was decided to be a good route for the railway!

 

[eastwestdivide]

Back when the line was built, was the sea as violent as it is now? Makes you wonder how they ever built it and why it was decided to be a good route for the railway!

Gradients might have been a factor in favour of a seaside route versus an inland route. Early railways tended to avoid steep gradients if possible. Non-coastal Devon is hilly.

 

[Aictos]

No, the line voltage is the same, however there is greater insulation between live and earthed parts and the catenary wire is replaced with contenary (contact wire used in place of catenary wire).

Ahh apologies, I thought it was a higher line voltage for some reason, probably because I saw it typed that way.

So could the same apply to Dawlish as I think it could?

 

[61653 HTAFC]

Gradients might have been a factor in favour of a seaside route versus an inland route. Early railways tended to avoid steep gradients if possible. Non-coastal Devon is hilly.

The southern end of the British mainland is slowly sinking due to something related to plate tectonics (I think)... higher ocean temperatures also add to the severity of storms.

The Dawlish route was of course the location of Brunel's failed "Atmospheric Railway" experiment.

 

[furnessvale]

A few thoughts:

3kV might have been less prone to short circuits due to lower risk of arcing.

Serious question.

I am not well up on electrickry matters but is 3kV DC less likely to arc than 25kV AC?

 

[61653 HTAFC]

DC needs more frequent grid feeders than AC, which adds to costs.

 

[samuelmorris]

Serious question.

I am not well up on electrickry matters but is 3kV DC less likely to arc than 25kV AC?

Tricky question, I believe the two conductors have to be a lot closer to produce an arc due to the lower voltage but once one starts, it's much more problematic on DC - check out this demonstration (though this appears to be PWM DC which is a little different)

(This however is a bit off-topic in the context of IET movements)

 

[pj334]

Back when the line was built, was the sea as violent as it is now? Makes you wonder how they ever built it and why it was decided to be a good route for the railway!

Perhaps passengers were made of tougher stuff in 1865 when this breach occured, a gentle walk sets you up nicely for your lunch ...

 

[yorksrob]

My point is that diversions alone won't justify the investment in an alternative route, so the route selected for a second line will need to generate traffic of its own (rather than abstracting from the coast route) for the next 30+ years outside of the few days each year that the Dawlish route is unavailable.

Indeed, which is precisely why a route linking Tavistock and Okehampton into the rest of the country is so necessary.

If there were an issue with the new stock, couldn't they just station a couple of thunderbirds in the area ?

 

[Bevan Price]

If some of the global warming predictions are anywhere near correct, most of the line between Exeter & Teignmouth will need to be replaced by 2050 - 2100.
Melting of the polar ice caps will raise sea levels by somewhere between 1 and 8 metres (about 3 - 25 feet.) -- most of the current line would be below sea level even at half the maximum predicted change.....and parts of Dawlish & Teignmouth may need to be evacuated.

 

[TRAX]

Build a shelter to cover the top and the side of the line.

 

[Lucan]

Gradients might have been a factor in favour of a seaside route versus an inland route.

The Dawlish route was of course the location of Brunel's failed "Atmospheric Railway" experiment.

And yet a claimed advantage of the atmospheric system was that it coped with gradients better, because wheel slip was not an issue. The atmospheric railway was a short-sighted lapse on Brunel's part, but perhaps it did occur to him that a flat-ish route was needed anyway because the tractive effort could never be more than 14.7 lbs x whatever the piston area was - at the impossible best.

 

[61653 HTAFC]

And yet a claimed advantage of the atmospheric system was that it coped with gradients better, because wheel slip was not an issue. The atmospheric railway was a short-sighted lapse on Brunel's part, but perhaps it did occur to him that a flat-ish route was needed anyway because the tractive effort could never be more than 14.7 lbs x whatever the piston area was - at the impossible best.

Rats eating the pipes didn't help either!

 

[twpsaesneg]

Serious question.

I am not well up on electrickry matters but is 3kV DC less likely to arc than 25kV AC?

The issue is more the salt spray breaking down the insulating properties of the insulators. 25kV is no massive issue in these conditions provided you increase the insulation distance accordingly, which is what was done at saltcoats. 3kV DC has its own issues with stray current corrosion as well as additional feeder stations being needed over 25kV AC.

But I can't see electrification happening there any time soon!

 

[Aictos]

OLE can be made weatherproof, there's plenty abroad but here in the UK, the line at Saltcoats does a pretty good job, see here:

The 802s have a 25kV bus on the roof that might need a bit of protection added.

I knew it was somewhere in Scotland but couldn’t remember where, ta for the photo

 

[Lucan]

salt spray breaking down the insulating properties of the insulators. 25kV is no massive issue in these conditions provided you increase the insulation distance accordingly, which is what was done at saltcoats

So did Saltcoats get its name from the coating of salt on the insulators?

 

[twpsaesneg]

So did Saltcoats get its name from the coating of salt on the insulators?

Pretty sure the town was there before the OLE....

 

[edwin_m]

Pretty sure the town was there before the OLE....

I would guess everything else in the vicinity gets coated with salt too.

 

[tbtc]

Do keep up! There are already outline plans for a diversionary route inland from Dawlish running nearly directly from Exeter to Newton Abbott. This will permit trains to continue to serve Newton Abbott and Torbay directly as well as Plymouth and Cornwall.

This has all been done to death before in other threads.

A "direct" route would be a benefit all year round (not just a handful fo weekends when there's engineering work or the highest of tides).

It would mean faster services from Cornwall/ Plymouth/ Torbay to Exeter/ Civilisation*.

It would make services more reliable (at the moment, the long distance services can easily be stuck behind the Torbay stoppers - at the moment the stoppers can take over forty minutes to get from Newton Abbott to Exeter whilst the long distance high speed services can take under twenty minutes - and any delay further north/east can mean that a Voyager/ 802/ HST ends up stuck behind a plodding Sprinter - a diversionary route would mean a faster journey for the longer distance passengers but also a much more reliable one, since any delays wouldn't inevitably mean following a 75mph DMU.

It would permit more local services to serve the local stations (Dawlish etc), since they wouldn't have an express chasing down their throat.

If the Okehampton route wasn't something closed down generations ago then it wouldn't be suggested now - it's significantly longer, it'd be very slow (given the terrain), there's only one place of any size (Tavistock, sub-15,000 people) - I've no problem with reconnecting Tavistock to Bere Alston with a simple shuttle towards Plymouth but let's not pretend that a route through OKehampton/Tavistock would ever be a "main" line - it only ever gets suggested by the kind of nostalgists who have a soft spot for building mass transportation through rural areas or some fantasy about reconnecting Waterloo to Tavistock because that's how things were a hundred years ago.

In fact, an Okehampton route would be so slow that a Rail Replacement Coach could probably make it from Exeter to Plymouth and back to Exeter along the fast A38 before a diverted service had trundled along the slow Okehampton alignment (with long sections of single track?) - the Stagecoach "Falcon" service takes around an hour to get from Sowton to Plymouth, which is similar time to the token GWR DMU from Exeter to Okehampton. And, the Stagecoach service has intermediate stops that a Rail Replacement Coach wouldn't have to worry about.

So we'd be spending hundreds of millions of pounds on an Okehampton route on the basis that it'd be nice to have a diversionary route a few days a year (so that a few people could sit on a train taking a couple of hours from Exeter to Plymouth, rather than putting them on a coach that could do the journey in half that time)? Or we could spend the money on a route giving people faster journeys on a daily basis, more reliable services, more scope for local services and finally making rail competitive from Exeter to Plymouth.

My point is that diversions alone won't justify the investment in an alternative route, so the route selected for a second line will need to generate traffic of its own (rather than abstracting from the coast route) for the next 30+ years outside of the few days each year that the Dawlish route is unavailable.

Agreed - all of this guff about "diversionary resilience" gets a certain type of enthusiast excited but it doesn't add up to a business case - there's certainly an argument for a Tavistock to Plymouth service (frequent commercial bus service, clear daily demand from the town to the main city in the area, no "pie in the sky" stuff about nice-to-have once-in-a-blue moon stuff) - but if you need to rely on "it'd be handy for a few days a year" to try to justify re-opening some rural route then that shows it's a pretty weak case - there are many areas where we could make genuine improvements for passengers day in day out - it's not like there isn't a long list of improvements we could be making to UK infrastructure.

But, I guess that if you're obsessed with re-openings then you're going to try to justify re-opening old lines at any opportunity.

(* - tongue in cheek - I can't be bothered to list the large number of places east of Exeter that would benefit)

 

[randyrippley]

The southern end of the British mainland is slowly sinking due to something related to plate tectonics (I think)... higher ocean temperatures also add to the severity of storms.

The Dawlish route was of course the location of Brunel's failed "Atmospheric Railway" experiment.

With modern materials a high-pressure pneumatic-driven railway could be made to work along that section. No electrics to worry about, no heavy motors or gensets or transformers. If the air tube got wet it wouldn't matter. A modern take on the Atmospheric Railway. A lot cheaper than erecting OHLE as well

 

[61653 HTAFC]

With modern materials a high-pressure pneumatic-driven railway could be made to work along that section. No electrics to worry about, no heavy motors or gensets or transformers. If the air tube got wet it wouldn't matter. A modern take on the Atmospheric Railway. A lot cheaper than erecting OHLE as well

All non-standard equipment though... as opposed to the mature technology that is OHLE and electric trains which can be bought pretty-much off the shelf.

 

[randyrippley]

All non-standard equipment though... as opposed to the mature technology that is OHLE and electric trains which can be bought pretty-much off the shelf.

Cheap, well understood mature technology though

 

[furnessvale]

With modern materials a high-pressure pneumatic-driven railway could be made to work along that section. No electrics to worry about, no heavy motors or gensets or transformers. If the air tube got wet it wouldn't matter. A modern take on the Atmospheric Railway. A lot cheaper than erecting OHLE as well

Hyperloop anyone? (Only joking)

 

[PTR 444]

I think the best option would be a brand new line similar to the Selby Diversion, diverging from the existing route at Matford near Exeter. It would run parallel to the A380 with a few tunnels underneath high ground before rejoining the line just north of Newton Abbott. It should be built to TGV standard (186mph) with overhead electrification from the start as it could form part of a future high speed corridor from Plymouth to Bristol and beyond.

Even with this new line in place, I still think reopening Okehampton - Bere Alston and the Teign Valley Line would be beneficial for improving local connections, even though they would hardly ever be used by intercity services.

 

[randyrippley]

Why not put the existing line into a pair of oversize pre-cast concrete pipes? Would protect the tracks from weather and rockfalls

 

[squizzler]

I see from Railjournal that - after departing under what might be perceived by many as a cloud from HS2 - Lord Berkeley has popped up in the far west with a plan to fix the Southwest's rail system, complete with Okehampton diversionary route.

£1.2bn rail upgrade proposed for southwest Britain

RAIL expert Lord Tony Berkeley and Mr Michael Byng, a chartered quantity surveyor and construction cost consultant, have published a £1.2bn plan to reopen lines and double-track existing lines in southwest Britain.

The Great South West plan, which will be promoted to the government, Local Enterprise Boards, local authorities, Network Rail (NR) and train operators, is aimed at increasing the capacity of the southwestern rail network, providing more resilience to flooding and storm damage, plugging gaps in the network, stimulating growth and reducing carbon emissions by encouraging a switch from road to rail.

Article continues over on Railjournal - but here are the highlights:

• reinstatement of double track between Exeter, Yeovil and Salisbury (£382.3m)
• reopening the railway between Okehampton, Tavistock and Bere Alston and upgrading existing sections to create an alternative to the storm-damage-prone Exeter – Plymouth main line (£426.5m)
• upgrading the Exeter – Barnstable line (£17.25m)
• reopening the Bodmin – Padstow line (£31.8m)
• reopening the Lostwithiel – Fowey freight line to passenger trains (£5.25m)
• reopening the direct link between Newquay and St Austell (£181.5m), and
• upgrading the Taunton – Minehead West Somerset Railway heritage line (£11.8m).

 

[Cowley]

Are those 1990s prices?
Surely most of those schemes would cost getting on for double that?

 

[Bald Rick]

Decimal point in the wrong place for Bodmin - Padstow.

 

[30907]

If my skim-read of the report is accurate, they want double track all the way from Salisbury to Plymouth and extra loops on the Barnstaple line (with Chapelton AND Umberleigh as P+R stations). No indication of suggested service frequencies, BCR etc.