Any news on proposals to build an alternative route between Exeter & Plymouth?

[edwin_m]

I think it is approx. 1km from the town centre viaduct, just Plymouth side of the missing bridge over Callington Road (A390), but well sited for the massive new housing development.

However the height difference means the walk from the centre of Tavistock is quite steeply uphill, so probably not very attractive to visitors or residents of other parts of the town.

 

[4141]

It wouldn't be the first time a listed monument has been replaced by a facsimilie.
You could regard it as the same bridge heavily repaired. After all, if it were a locomotive just about all of it would have been replaced over the same time scale, but its still the same loco...........

AKA The Trigger's Broom Scenario...

 

[Cliveblackpool]

Demolishing Meldon Viaduct would be very expensive, one of the reasons it wasn't taken down years ago !!
Meldon viaduct was the reason why the line was closed by BR, bit like Ribblehead viaduct was damaged beyond repair (water ingress) Amazingly that one was repaired!
Choices are overhaul it or easier to build a new one!
(NR report costings was reinstating the line as a double track modern railway)
Giving CrossCountry some of GWR HST's or other trains, instead of the Voyagers would help reduce disruption at Dawlish, but they are not interested investing much in Devon, Cornwall etc..

 

[Charlie Smythe]

I don't think that's doable, as MarkyT points out the current structure is a listed monument.

Just come a across some shots I took of Meldon Viaduct in June 2015, 1st view is of north side, 2nd shows the south structure, both look in very good order cosmetically at least.

I believe that the sections that are in poor condition are lower down below the trees and undergrowth, not the actual deck.

 

[Charlie Smythe]

Demolishing Meldon Viaduct would be very expensive, one of the reasons it wasn't taken down years ago !!
Meldon viaduct was the reason why the line was closed by BR, bit like Ribblehead viaduct was damaged beyond repair (water ingress) Amazingly that one was repaired!
Choices are overhaul it or easier to build a new one!
(NR report costings was reinstating the line as a double track modern railway)
Giving CrossCountry some of GWR HST's or other trains, instead of the Voyagers would help reduce disruption at Dawlish, but they are not interested investing much in Devon, Cornwall etc..

I believe that it would be a mistake to reinstate the line as a single track with some passing loops. Look at the West of England Line (Basingstoke to Exeter via Salisbury) That had its second track ripped up and now it cant keep up with the number of trains the line requires so much so that DCC wants to build a 3 mile passing loop. It will be so much better as a double track railway.

 

[MarkyT]

I believe that it would be a mistake to reinstate the line as a single track with some passing loops. Look at the West of England Line (Basingstoke to Exeter via Salisbury) That had its second track ripped up and now it cant keep up with the number of trains the line requires so much so that DCC wants to build a 3 mile passing loop. It will be so much better as a double track railway.

That section deserves an additional 3 mile loop because there are fairly concrete plans for an extra regular interval service. Full doubling throughout to Axminster could be 10 times the price of that and all the way to Yeovil a further similar figure and would kill the new service scheme stone dead if it had to carry that capital cost. Via Okehampton, the increment for constructing a new double versus single line would not be such a radical difference on the new sections, but would also mean complete reconstruction of the existing single track sections. It isn't required though for an hourly or even a half-hourly frequency. For a local service or an extension of the Waterloo trains, a very small number of well sited long dynamic loops, ideally surrounding a station, as at Axminster, is all that's required. Any other stations could be provided with a single platform for both directions which saves a lot of money on construction and access etc. Creating a longer double line through the Crediton area, where the line is shared with Barnstaple services, would be more beneficial, as would at least some double track past the junction near St Budeaux, for resilience and flexibility. In the event of diversions, longer distance trains would simply replace the local Okehampton services in the same paths so no more capacity is required. For future double track proofing I suggest a 'no active prevention strategy', with 'active provision' in terms of new abutments and pier foundations within reason, but not structural steelwork for the new Meldon for example, so in the unlikely event more double track was required in that area a similar strategy to that employed by the original bridge builders could be implemented.

 

[hwl]

That section deserves an additional 3 mile loop because there are fairly concrete plans for an extra regular interval service. Full doubling throughout to Axminster could be 10 times the price of that and all the way to Yeovil a further similar figure and would kill the new service scheme stone dead if it had to carry that capital cost. Via Okehampton, the increment for constructing a new double versus single line would not be such a radical difference on the new sections, but would also mean complete reconstruction of the existing single track sections. It isn't required though for an hourly or even a half-hourly frequency. For a local service or an extension of the Waterloo trains, a very small number of well sited long dynamic loops, ideally surrounding a station, as at Axminster, is all that's required.

The problem is that the West of England line theoretically works but in practice can't handle all the perturbations from delays elsewhere (e.g. from delays Basingstoke - Waterloo) so the service goes to pot very quickly and is very difficult to recover especially with the current unit shortages increasing crowding levels and dwell times.

 

[Charlie Smythe]

That section deserves an additional 3 mile loop because there are fairly concrete plans for an extra regular interval service. Full doubling throughout to Axminster could be 10 times the price of that and all the way to Yeovil a further similar figure and would kill the new service scheme stone dead if it had to carry that capital cost. Via Okehampton, the increment for constructing a new double versus single line would not be such a radical difference on the new sections, but would also mean complete reconstruction of the existing single track sections. It isn't required though for an hourly or even a half-hourly frequency. For a local service or an extension of the Waterloo trains, a very small number of well sited long dynamic loops, ideally surrounding a station, as at Axminster, is all that's required. Any other stations could be provided with a single platform for both directions which saves a lot of money on construction and access etc. Creating a longer double line through the Crediton area, where the line is shared with Barnstaple services, would be more beneficial, as would at least some double track past the junction near St Budeaux, for resilience and flexibility. In the event of diversions, longer distance trains would simply replace the local Okehampton services in the same paths so no more capacity is required. For future double track proofing I suggest a 'no active prevention strategy', with 'active provision' in terms of new abutments and pier foundations within reason, but not structural steelwork for the new Meldon for example, so in the unlikely event more double track was required in that area a similar strategy to that employed by the original bridge builders could be implemented.

I just think that they would be better off having double all the way from Okehampton to Bere Alston and hopefully to St Budeaux as well. It is already single track from Okehampton to Penston Junction (Barnstable and Okehampton line split) Then double track from there to Crediton and then back to single all they way to Cowley Bridge junction. If it was double all the way from Cowley Bridge to St Budeaux then it would all for far more services.

 

[HowardGWR]

I just think that they would be better off having double all the way from Okehampton to Bere Alston and hopefully to St Budeaux as well. It is already single track from Okehampton to Penston Junction (Barnstable and Okehampton line split) Then double track from there to Crediton and then back to single all they way to Cowley Bridge junction. If it was double all the way from Cowley Bridge to St Budeaux then it would all for far more services.

See the highlighted word. You state you are local -that's unforgivable isn't it?

 

[Charlie Smythe]

See the highlighted word. You state you are local -that's unforgivable isn't it?

Should be Barnstaple i know. And i wouldn't call Barnstaple local, as its not.

 

[Charlie Smythe]

However the height difference means the walk from the centre of Tavistock is quite steeply uphill, so probably not very attractive to visitors or residents of other parts of the town.

The new station may be in an inconvenient place but look at Bere Alston, that is know were near the town centre and it has a usage of 40,000 pa, not bad for a small town.

 

[yorksrob]

I just think that they would be better off having double all the way from Okehampton to Bere Alston and hopefully to St Budeaux as well. It is already single track from Okehampton to Penston Junction (Barnstable and Okehampton line split) Then double track from there to Crediton and then back to single all they way to Cowley Bridge junction. If it was double all the way from Cowley Bridge to St Budeaux then it would all for far more services.

Even in that scenario, a short single track section over Meldon viaduct wouldn't be that much of a problem. The main line from Tonbridge to Hastings has four such sections and manages to run a reasonably intensive service.

 

[Charlie Smythe]

Even in that scenario, a short single track section over Meldon viaduct wouldn't be that much of a problem. The main line from Tonbridge to Hastings has four such sections and manages to run a reasonably intensive service.

I think it should be double track all the way although, as you say, a single track over Meldon Viaduct wouldn't be to much of an issue. We will have to see what network rail come up with.

 

[MarkyT]

Even in that scenario, a short single track section over Meldon viaduct wouldn't be that much of a problem. The main line from Tonbridge to Hastings has four such sections and manages to run a reasonably intensive service.

Just setting up to build any kind of brand new bridge at Meldon would be hugely expensive, and making it double might add (only!) say 50%. The larger costs would be in rebuilding a wider alignment throughout the route with the additional bridge reconstructions and retaining structures that might be required to maintain modern clearances, more extensive digging to reinforce the subbase layer and create more complex drainage etc, and of course the doubling of the rail, sleeper and ballast requirement. At least on the new part of the route it could be done under no train conditions as a green field site. Under normal use this would be carrying at most an hourly DMU in each direction at say 90mph however so in my view double track thoughout would be excessive.

 

[Cliveblackpool]

Imo double track would be needed between Crediton and Cowley bridge junction, or it would impact on Barnstaple services. Best to have double to Coleford Junction, or at least 2 separate tracks, as in 1970.
Bere Alston is on the Bere peninsular, with poor roads (eg picturesque Denham Bridge across the Tavy) to Plymouth, the reason why the service was kept open after Dr Beeching.

 

[yorksrob]

Just setting up to build any kind of brand new bridge at Meldon would be hugely expensive, and making it double might add (only!) say 50%. The larger costs would be in rebuilding a wider alignment throughout the route with the additional bridge reconstructions and retaining structures that might be required to maintain modern clearances, more extensive digging to reinforce the subbase layer and create more complex drainage etc, and of course the doubling of the rail, sleeper and ballast requirement. At least on the new part of the route it could be done under no train conditions as a green field site. Under normal use this would be carrying at most an hourly DMU in each direction at say 90mph however so in my view double track thoughout would be excessive.

Also a valid view, so long as enough double track is around to enable the proposed service as well as diversions when necessary.

 

[Charlie Smythe]

Just setting up to build any kind of brand new bridge at Meldon would be hugely expensive, and making it double might add (only!) say 50%. The larger costs would be in rebuilding a wider alignment throughout the route with the additional bridge reconstructions and retaining structures that might be required to maintain modern clearances, more extensive digging to reinforce the subbase layer and create more complex drainage etc, and of course the doubling of the rail, sleeper and ballast requirement. At least on the new part of the route it could be done under no train conditions as a green field site. Under normal use this would be carrying at most an hourly DMU in each direction at say 90mph however so in my view double track thoughout would be excessive.

Its going to to be expensive either way especially as you are building a new bridge in challenging terrain with challenging ground conditions.

 

[MarkyT]

Imo double track would be needed between Crediton and Cowley bridge junction, or it would impact on Barnstaple services. Best to have double to Coleford Junction, or at least 2 separate tracks, as in 1970.

Looking at running times I think a 30 minute interval service could run on the single line between Exeter and Crediton but it would be more resilient if the single section was shorter. The double needn't go all the way to the GW junction (and it didn't for some time anyway even before Exeter resignalling). Any shortening of the single line would be a resilience and planning flexibility benefit and placing the new single to double connection just west of Newton St Cyres would avoid having to bring back into use to the former second platform there, with the access challenges that would pose. Beyond Crediton, the two parallel single lines could remain independent as today or, again for more resilience and planning flexibility, could be combined into a double track arrangement as far as Coleford junction. Overall these measures would require no more points in the final layout than exist in today's, although they would be more spread out clearly.

Bere Alston is on the Bere peninsular, with poor roads (eg picturesque Denham Bridge across the Tavy) to Plymouth, the reason why the service was kept open after Dr Beeching.

Yes a fortunate survivor, with an appreciable number of RN Dockyard workers resident in the area at the time I understand. I would definitely advocate a long loop at that end of the line to regulate traffic, allowing an Exeter-bound train to stand clear of the GW line into Cornwall while waiting for an opposing late runner, and providing capacity for the Gunnislake service to continue running through to Plymouth.

 

[AndrewE]

Just setting up to build any kind of brand new bridge at Meldon would be hugely expensive, and making it double might add (only!) say 50%. The larger costs would be in rebuilding a wider alignment throughout the route with the additional bridge reconstructions and retaining structures that might be required to maintain modern clearances, more extensive digging to reinforce the subbase layer and create more complex drainage etc, and of course the doubling of the rail, sleeper and ballast requirement. At least on the new part of the route it could be done under no train conditions as a green field site. Under normal use this would be carrying at most an hourly DMU in each direction at say 90mph however so in my view double track thoughout would be excessive.

Why "hugely" expensive? If it's part of the national infrastructure that needs doing then it needs costing into the scheme... Of course we need to ensure that someone opposed to the reopening doesn't design a ludicrously over-specified bridge to make sure it fails the first prioritisation stage of route selection, but with modern FOI and other things such fixes should be more transparent nowadays. Anyway I agree a double-track bridge should not be much more than a single track one, even if single line was laid initially.
And why would setting up be a problem? access shouldn't really be a problem at all: after all there is a disused railway alignment (3 actually, 2 of them directly or indirectly just off the dualled A30) leading straight to the ends of the viaduct that could be used as access roads. Lots of bridges are built in far more isolated places.

 

[MarkyT]

Also a valid view, so long as enough double track is around to enable the proposed service as well as diversions when necessary.

As I said earlier, on the handful of days they might run the longer distance diversions would simply slot into the paths normally used by the local service. They might call at some or all of the normal local stations depending on factors such as platform length and SDO provision/compatibility with any gaps in services covered by replacement buses.

 

[yorksrob]

As I said earlier, on the handful of days they might run the longer distance diversions would simply slot into the paths normally used by the local service. They might call at some or all of the normal local stations depending on factors such as platform length and SDO provision/compatibility with any gaps in services covered by replacement buses.

I just don't want to replicate the situation which existed for many years on the WoE line where the local service had to be replaced by buses whilst IC services were diverted along it.

 

[AndrewE]

Its going to to be expensive either way especially as you are building a new bridge in challenging terrain with challenging ground conditions.

How do you know the ground conditions? We haven't had a definitive answer yet to why a girder bridge was built. I would go partly with the "cheapness and speed of construction" theory. You can bring in lots of relatively lightweight lengths of steel (or wrought iron) and fabricated sections, crane them out over the drop and bolt them in place. In fact, with a rail-mounted crane on a temporary pad on the abutment I bet you could do exactly the same again. There's a fairly high-tech steel fabrication facility only about 20 miles down the line SW, I think.
The other reason I thought they might have selected a light structure was if the bedrock was in fact very deep beneath the current valley floor, so digging the foundations for a solid stone structure would not have been reasonably practicable (i.e. cost-effective.)

 

[MarkyT]

Why "hugely" expensive? If it's part of the national infrastructure that needs doing then it needs costing into the scheme... Of course we need to ensure that someone opposed to the reopening doesn't design a ludicrously over-specified bridge to make sure it fails the first prioritisation stage of route selection, but with modern FOI and other things such fixes should be more transparent nowadays. Anyway I agree a double-track bridge should not be much more than a single track one, even if single line was laid initially.
And why would setting up be a problem? access shouldn't really be a problem at all: after all there is a disused railway alignment (3 actually, 2 of them directly or indirectly just off the dualled A30) leading straight to the ends of the viaduct that could be used as access roads. Lots of bridges are built in far more isolated places.

I mean hugely expensive compared to 'normal' construction on earthworks and with occasional more modest structures. Of course that relates only to the relatively short proportion of the route reconstruction distance the new bridge would represent, but nevertheless the bridge would represent a highly significant proportion of the total cost and the BCR is dependent on the overall cost of the entire scheme.

 

[MarkyT]

I just don't want to replicate the situation which existed for many years on the WoE line where the local service had to be replaced by buses whilst IC services were diverted along it.

For a small number of local passengers on occasional days it isn't worth double tracking throughout, on the WoE or the Okehampton routes. The diverted trains can still stop at some of the major stations en route where platforms are deliberately made long enough or suitable SDO systems are available so the numbers of people affected are miniscule compared to the numbers that can remain on main line trains due to the diversionary route being available.

 

[yorksrob]

For a small number of local passengers on occasional days it isn't worth double tracking throughout, on the WoE or the Okehampton routes. The diverted trains can still stop at some of the major stations en route where platforms are deliberately made long enough or suitable SDO systems are available so the numbers of people affected are miniscule compared to the numbers that can remain on main line trains due to the diversionary route being available.

True, but as an alternative to redoubling, you could include dynamic loops that are long enough to be split into two sections. That way you could run pairs of trains in flight when necessary, which would be useful not only for diversions, but also for freight, Q diagrams, departmentals etc.

 

[MarkyT]

True, but as an alternative to redoubling, you could include dynamic loops that are long enough to be split into two sections. That way you could run pairs of trains in flight when necessary, which would be useful not only for diversions, but also for freight, Q diagrams, departmentals etc.

That is possible although not without cost and I believe the technique has been looked at in future options for the WoE. Axminster loop is already three block sections long as it is, so you could theoretically stack three train in each direction there today although how they could get in there in the first place is debateable! You also need many closely spaced flighting signals along the single line sections so the trains can remain close together. ETCS might be able to provide such facilities more economically one day.

 

[yorksrob]

That is possible although not without cost and I believe the technique has been looked at in future options for the WoE. Axminster loop is already three block sections long as it is, so you could theoretically stack three train in each direction there today although how they could get in there in the first place is debateable! You also need many closely spaced flighting signals along the single line sections so the trains can remain close together. ETCS might be able to provide such facilities more economically one day.

I think its worth building in some additional capacity from the start, rather than having to re-signal prematurely.

 

[Sir Felix Pole]

I have finally located my copy of the 'Okehampton Line' by the Irwell Press published in 2008 (2nd edn) which has a detailed account of the construction of the whole Exeter to Plymouth LSW route and its subsequent operation. The authors suggest that there were concerns about the wind resistance that a high (120ft) masonry structure at Meldon would offer in such an exposed location, plus the funnelling effect of the nearby gorge. The gorge was largely flooded in the 1970s with the construction of the nearby Meldon Dam. I do not see any access issues building a Meldon Viaduct II - there is a road under the existing viaduct used by roadstone lorries to access the quarry when it was open and a large working area in the quarry itself for materials etc. There were no access issues building the dam either - indeed the railway formation was used for construction vehicles - hence one of the few missing overbridges at Prewley Moor where access from the A386 was gained.

 

[Ash Bridge]

Some very interesting information about the viaduct there, many thanks for posting.

 

[Brush 4]

Good to see the official scheme pages have ignited positive ideas here. I don't see though how building a new Meldon Viaduct plus new rail formation on either side, could possibly be cheaper than strengthening and further refurb of the existing bridge, unless some creative accounting is involved for the latter. If a new bridge is likely to ruin the BCR, sabotaging the whole route opening, don't do it. Ribblehead works fine as a single track, so could Meldon, with the cycle path alongside, as it already is up from Okehampton.

Actually, on that point, the Oke Parkway proposals include the Dartmoor rly services so ironically, the cycle path as far as Meldon Quarry station would have to go, as the 25mph trains would presumably need their own track, with the other track for modern trains, unless they are allowed to share one track, which seems unlikely.