Welwyn Viaduct section doubling - How?

[dstrat]

If there was money in the bank, and the ground was right, wouldn't it be possible to dive under Welwyn and emerge a 1.5mile or 2 back onto the mainline. Surely this can't be beyond the realm of possibility with all the tunnels built on HS1 and what is being proposed on HS2.

 

[Peter Mugridge]

What sort of gradient would that require?

 

[Rick1984]

They should build the new tunnels and bridge. The new bridge should look nothing like the the old one and should be architecturally impressive to complement the old viaduct. This is the sort of thing they'd do in france.

 

[talltim]

One other thing to consider is that much of the mainline infrastructure (as opposed to yards etc) removed under BR was for goods traffic and not particarly suitable for running more/faster passenger trains anyway, and often not suitable for modern freight due to train lengths. However disposing of the land was very short sighted.

 

[Tomnick]

Welwyn North did have a number of sidings and from what I've seen there was a down loop but this was not used for passenger trains. It was more a reception siding that had access from both directions. Some local 'mature' expects told me that.

Just discovered a pre-resignalling diagram of Welwyn North, which suggests that there was never a facing connection into the through siding on either side of the line - I suspected that'd have been the case (anything to avoid facing points!), but wasn't sure.

 

[Lee_Again]

Happy to accept I'm wrong on that point. I did say it was based on some locals and no absolute fact. Possibly time playing tricks with their memory.

Does look as if it was physically possible, not withstanding the facing point problem!

In any event shortening of the double track section, removing the station at Welwyn North completely or adding in loops, none of this will solve the overall problem. Only putting in a new viaduct and tunnels will do this.

The locals in that area are have large funds available and would make the legal process a nightmare. Something that has already proved to be the case.

I've already showed how only modest investment is needed to give 4 extra pasths and better scheduling could add 1 or 2 others. How many extra paths are needed?

 

[Tomnick]

Don't worry, I wasn't out to prove you wrong! Just posted the link to the diagram as a point of interest, as I wasn't sure myself. I agree that loops at Welwyn North will do nothing to solve the capacity, as your stoppers will end up eating into more paths overall.

I don't know what the ultimate grand plan is for local services on the Hertford loop, but one way of fitting additional through services in might be, in the peak at least, to split the local service into two groups: one fast to Gordon Hill then all stations north of there, and another all stations to, and terminating at, Gordon Hill. Planned carefully, that might just about give a path for a through train without having to loop stoppers (and thus extend local journey times).

 

[D365]

Can't argue with any of that - I know that other people seem to have amazing hindsight, but BR acted on the hand they had been dealt.

If they'd known about demand patterns of the last twenty years, they'd never have bothered with shorter term things like Pacers, but based on the information known at the time, they did the best they could.



The sparks effect has taken on mythical status amongst some enthusiasts, like a transport version of the Jedi "force" - as if the move to EMUs suddenly attracts larger numbers of passengers.

The way I see it, if you increase the frequency and run longer trains, you'll attract more passengers. Nothing to do with "sparks".

Agreed.

Lot's of interesting ideas in this thread. Makes a pleasent change that realistic options have been discussed rahter than the normal fanciful mutil billion pound projects that will never happen.

In an earlier post I discussed routing trains around the loop. I was refering to the Finsbury Pk, Stevenage fasts and non-stop Cambridge services. There are typically four of these per hour. That's why I suggested increasing the slow services on the loop to 4tph from the present 2 or 3 tph. With the slows stopping in new loops at Gordon Hill the fasts can pass unhindered.

Welwyn North did have a number of sidings and from what I've seen there was a down loop but this was not used for passenger trains. It was more a reception siding that had access from both directions. Some local 'mature' expects told me that.

Somebody earlier mentioned the new Thameslink franchise. Part of my grand plan for the inner subs would to be have 4tp from WGC and 4tph from Hertford (and possible further north-Letchworth would be easy once the viaduct at Hitchin is completed). 4tph would run to Moorgate and 4tph would run onto the North London Line and continue to South East London or where ever is suitable on that service. I know the tunnel linking the NLL with the ECML is single bore and the junction with the NLL is not grade seperated but with some investment there (ok, quite a bit of investment) you would be linking two areas of the home counties that could benefit the both.

And wouldn't it be great if they continued the Moorgate tunnels to Bank and joined the Drain to Waterloo and then surfaced somewhere around Vauxhall. A fairly cheap (relative term!!) way of getting at least 4tph from Herts to Surrey.

What with all these cross London tunnels and HS2 what future King's Cross. A couple of services to Hull and Lincoln!!!

It's interesting that when the New Barnet > Potters Bar section was quadruppled in the early 50's (which included no less then 3 new tunnels) it was not also done at Welwyn. I would love to read the investment notes from that period if anybody has details of where to find them.

Very interesting plans you have there. I don't think direct services from ECML/NCL to NLL would be that useful with the good interchange at H&I, especially if you were to connect NCL Moorgate to a rebuilt W&C at Bank, with a new station at Blackfriars as a "Thameslink 2".

Back in reality, I don't like how Peterborough is getting 2tph onto Thameslink while Welwyn slows get 4tph, which could easily be kept on Moorgate. Split this between Peterborough/Cambridge and keep Welwyn on Moorgate or Thameslink 2 and I'd be happy! Will be interesting getting everything over Digswell/the viaduct.

 

[philjo]

They should build the new tunnels and bridge. The new bridge should look nothing like the the old one and should be architecturally impressive to complement the old viaduct. This is the sort of thing they'd do in france.

The problem with this is that the viaduct is listed. The view of the viaduct from one side is protected from any development but the other side is where most of the adjacent property is so would affect at lot more local residents as their properties would need to be demolished.


I think it was Roger Ford who once suggested in Modern Railways putting in a single track cantilver on the side of the existing viaduct to extend the down slow to Welwyn North to a new 3rd platform (as a bi-di line).
Some of the Morgate-WGC services could use this line to Welwyn North where they would terminate & reverse back to London, crossing over ont he exsiting flyover south of WGC.

In peak hours other services would not serve Welwyn North on the main lines in the direction of peak flow.
No tunnels needed for that option.

 

[A0]

I don't know why people are so keen on terminating at Stevenage.

Probably because the incremental traffic to Hitchin & Letchworth on the Hertford North services isn't very big?

I think all Hertford trains that currently terminate at SVG should run through to Letchworth.

For what purpose?

Terminating at SVG and running back round the loop via the downside is inconveniant for passengers coming from the north, especially with luggage. Once the Hitchin flyover is complete there shouldn't be a need to terminate at SVG - if there is, open the extra platform at Letchworth, it'd probably take less work.

I'm guessing that the traffic from Letchworth to Hertford (or intermediate stations on the loop to Finsbury Pk) with huge amounts of luggage is negligible. People from north of Hitchin on the mainline are more likely to change at Stevenage in any case.

I'd reopen the Welwyn-Hertford line as double track, with a flyover at the Welwyn end and tracks running either side of the viaduct at Hertford, meaning there'd be no conflicting moves.
I'd reopen Coles Green station and serve it by extending one train per hour from WGC to LET via HFN and SVG.

Good luck with that - the Welwyn Hertford line wasn't double track originally. Add to that the formation has been completely built over all the way through Welwyn Gdn City and you'll find that option doesn't exist. And I'm not sure where you'd find the space for a flyover north of Welwyn GC station - the Hertford line diverged just north of Hunters Bridge - the west side of the line is full with the carriage sidings - which are well used.

During peak times the branch could be used to run fast trains onto the mainline, avoiding the bottleneck. This option would probably be more cost effective than quadrupling the whole loop.

[/QUOTE]

But you'll still have a bottleneck from Stevenage to Hertford, together with a lower linespeed than the mainline via Knebworth.

I'm not sure what the answer is to the Welwyn "problem" - a tunnel is probably impractical - the line comes in at a much higher level than the foot of the valley - hence the viaduct. The foot of the valley has got a river running through it, so I suspect an extensive tunnel is out of the question.

The viaduct is listed, which limits opportunities there and there's the added issue that you've got two tunnels immediately north of Welwyn North station.

And there are no other obvious diversion options.

 

[Aictos]

The easiest solution to improving the Hertford Loop is a number of things....

1.) Increase number of signals from Crews Hill to Langley Junction especially between Hertford North and Langley Junction as it's the long distances between signals which really restrict the use of trains.

2. Increase the line speeds to something along the lines of 75mph for freight trains and 85/90mph for passenger trains, there are some sections which have slow line speeds which really could do with increasing.

Do that and it might mean diverted services not losing that much time compared to running on the mainline.

Would it affect East Coast that badly if they ran their Newark Northgate services via the Hertford Loop as a cheap way of keeping up route knowledge for their crews, they do have 30 mins to turnround at Newark Northgate so could easily spend 10 mins going via Hertford.

Do that and it frees up a path in the off peak across the viaduct at Welwyn

 

[Tomnick]

If the main problem is fast trains catching up with stoppers, additional signals (presumably by increasing from 3-aspect to 4-aspect signals) south of Hertford North won't do much, other than possibly a few sections at either end of the line (to allow the 'next' stopper to more closely follow a fast train onto the double-track section). I think the headway north of Hertford North is six minutes - so yes, that could do with some further looking at!

 

[philjo]

Probably because the incremental traffic to Hitchin & Letchworth on the Hertford North services isn't very big?

I'm guessing that the traffic from Letchworth to Hertford (or intermediate stations on the loop to Finsbury Pk) with huge amounts of luggage is negligible. People from north of Hitchin on the mainline are more likely to change at Stevenage in any case.

I think Fred26 was referring to the fact that if the Hertford train started from Letchworth then it would use Platform 1 at Stevenage. This means it would be a cross platform change at Stevenage for passengers alighting from East Coast Services wishing to travel to stations on the Hertford Loop. At the moment they have to cross over to platform 4.

It also gives a regular service from Letchworth to Hertford - there is one off-peak on weekdays. At other times it requires changing at Stevenage but the connections are terrible - usually a 25 minute wait.

Under the current arrangement Platform 4 at Stevenage is also blocked for about 15 minutes each hour, effectively extending the single northbound line through Welwyn North from WGC to Hitchin.

 

[Fred26]

Probably because the incremental traffic to Hitchin & Letchworth on the Hertford North services isn't very big?



For what purpose?


I'm guessing that the traffic from Letchworth to Hertford (or intermediate stations on the loop to Finsbury Pk) with huge amounts of luggage is negligible. People from north of Hitchin on the mainline are more likely to change at Stevenage in any case.

Exactly. It's inconveniant for passengers to have to switch platforms, up and down stairs or lifts, at Stevenage if they're coming from north of Stevenage for Hertford services. That is exactly why I'd extend the current terminators to Letchworth - so all up trains would run from the upside.
--- old post above --- --- new post below ---

I think Fred26 was referring to the fact that if the Hertford train started from Letchworth then it would use Platform 1 at Stevenage. This means it would be a cross platform change at Stevenage for passengers alighting from East Coast Services wishing to travel to stations on the Hertford Loop. At the moment they have to cross over to platform 4.

It also gives a regular service from Letchworth to Hertford - there is one off-peak on weekdays. At other times it requires changing at Stevenage but the connections are terrible - usually a 25 minute wait.

Under the current arrangement Platform 4 at Stevenage is also blocked for about 15 minutes each hour, effectively extending the single northbound line through Welwyn North from WGC to Hitchin.

That's correct.

 

[Ploughman]

If the main problem is fast trains catching up with stoppers, additional signals (presumably by increasing from 4-aspect to 3-aspect signals) south of Hertford North won't do much, other than possibly a few sections at either end of the line (to allow the 'next' stopper to more closely follow a fast train onto the double-track section). I think the headway north of Hertford North is six minutes - so yes, that could do with some further looking at!

There was me thinking 3 to 4 was an increase.
But Hey this is the Modern Railway so an increase from 4 Aspect to 3 Aspect must be the way forward.

 

[Bald Rick]

Lot's of interesting ideas in this thread. Makes a pleasent change that realistic options have been discussed rahter than the normal fanciful mutil billion pound projects that will never happen.

In an earlier post I discussed routing trains around the loop. I was refering to the Finsbury Pk, Stevenage fasts and non-stop Cambridge services. There are typically four of these per hour. That's why I suggested increasing the slow services on the loop to 4tph from the present 2 or 3 tph. With the slows stopping in new loops at Gordon Hill the fasts can pass unhindered.

Welwyn North did have a number of sidings and from what I've seen there was a down loop but this was not used for passenger trains. It was more a reception siding that had access from both directions. Some local 'mature' expects told me that.

Somebody earlier mentioned the new Thameslink franchise. Part of my grand plan for the inner subs would to be have 4tp from WGC and 4tph from Hertford (and possible further north-Letchworth would be easy once the viaduct at Hitchin is completed). 4tph would run to Moorgate and 4tph would run onto the North London Line and continue to South East London or where ever is suitable on that service. I know the tunnel linking the NLL with the ECML is single bore and the junction with the NLL is not grade seperated but with some investment there (ok, quite a bit of investment) you would be linking two areas of the home counties that could benefit the both.

And wouldn't it be great if they continued the Moorgate tunnels to Bank and joined the Drain to Waterloo and then surfaced somewhere around Vauxhall. A fairly cheap (relative term!!) way of getting at least 4tph from Herts to Surrey.

What with all these cross London tunnels and HS2 what future King's Cross. A couple of services to Hull and Lincoln!!!

It's interesting that when the New Barnet > Potters Bar section was quadruppled in the early 50's (which included no less then 3 new tunnels) it was not also done at Welwyn. I would love to read the investment notes from that period if anybody has details of where to find them.

Have to say this is my favourite post ever on this forum. The contrast between the first paragraph and the rest is magnificent.


--- old post above --- --- new post below ---

Of course it is nothing to do with sparks. It's a figure of speech!

Electrification results in faster journey times, and lower costs can (and should) result in longer trains and sometimes more frequent services.

The phrase stems from, I think, the Midland Suburban electrification in the early 80s. Although badged as electrification, this was a Total Route Modernisation, with electrification, new trains, resignalling and higher line speeds all done concurrently. Traffic growth afterwards was spectacular. Bear in mind that pre electrification there were 3 trains a DAY from the MML to Moorgate via Farringdon.

By chance I am currently skimming through Modern Railways from 1976 onwards, the time when this was authorised and delivered. Almost every edition in 1978 and 1979 has a letter stating what a rubbish idea electrification of this line is, and that the money would be much better spent electrifying to Blackpool or similar. Also that any idea of linking up with the Southern via Snow Hill is plainly bananas, and in the words of the then Editor "a solution looking for a problem".


Which brings me neatly to my question. If quadrupling Welwyn viaduct is the solution, what is the problem?

 

[Tomnick]

There was me thinking 3 to 4 was an increase.
But Hey this is the Modern Railway so an increase from 4 Aspect to 3 Aspect must be the way forward.

Well spotted - an error on my part, of course. My original post has been corrected!

 

[A0]

I think Fred26 was referring to the fact that if the Hertford train started from Letchworth then it would use Platform 1 at Stevenage. This means it would be a cross platform change at Stevenage for passengers alighting from East Coast Services wishing to travel to stations on the Hertford Loop. At the moment they have to cross over to platform 4.

It also gives a regular service from Letchworth to Hertford - there is one off-peak on weekdays. At other times it requires changing at Stevenage but the connections are terrible - usually a 25 minute wait.

Under the current arrangement Platform 4 at Stevenage is also blocked for about 15 minutes each hour, effectively extending the single northbound line through Welwyn North from WGC to Hitchin.

I thought the plan was for a bay at Stevenage to remove the constraint on existing platforms? If that happened there'd b far less justification for extending to Letchworth.

I don't believe that Letchworth - Hertford is a major passenger flow -neither are particularly large places, nor are they 'destinations' in the way Stevenage is. And I'm doubtful that there are significant numbers alighting from EC services at Stevenage to travel onto destinations on the Hertford loop - on that basis the loss of cross platform interchange shouldn't be regarded as a significant problem - lots of interchanges aren't cross platform, some of which are much more significant than this.

 

[Fred26]

I thought the plan was for a bay at Stevenage to remove the constraint on existing platforms? If that happened there'd b far less justification for extending to Letchworth.

I don't believe that Letchworth - Hertford is a major passenger flow -neither are particularly large places, nor are they 'destinations' in the way Stevenage is. And I'm doubtful that there are significant numbers alighting from EC services at Stevenage to travel onto destinations on the Hertford loop - on that basis the loss of cross platform interchange shouldn't be regarded as a significant problem - lots of interchanges aren't cross platform, some of which are much more significant than this.

There are no plans for a bay platform at Stevenage. None.

It's not just East Coast passengers that want to travel via the loop, but passengers from other FCC stations. Again, I insist that all up trains should run from the same side of the station.

 

[tbtc]

If quadrupling Welwyn viaduct is the solution, what is the problem?

Good question.

I'd say that the viaduct is a bottleneck stopping places like Cambridge and Leeds seeing an improved service (since there's no space on the West Anglia route for fast Cambridge services or on the MML for fast Leeds services.

However, since the line from London to Peterborough isn't all four tracked, sorting out Welwyn would just push the bottleneck further up the line (rather than resolving the whole thing).

I guess that's one reason I'm in favour of HS2 - instead of "tackling" various bottlenecks by moving them slightly further along a line, it would bypass such things completely.

 

[yorksrob]

However, since the line from London to Peterborough isn't all four tracked, sorting out Welwyn would just push the bottleneck further up the line (rather than resolving the whole thing).

Don't forget, you would at least get four tracks through to Hitchin which is where a number trains peel off towards Cambridge anyway. I'd say it's a fairly logical ambition.

 

[jon0844]

I'd expect there's a fair few people along the Hertford Loop that might want to get to Stevenage for onward trips along the ECML and to Cambridge etc.

When I've needed to go from Hatfield to Hertford, I've gone via Stevenage. I've often considered it might be quicker (given the poor connection times at Stevenage) to go via London though.

 

[Lee_Again]

Have to say this is my favourite post ever on this forum. The contrast between the first paragraph and the rest is magnificent.

Surprised you were the only one to mention this. I my initial paragraph was true, IMHO, so I thought I'd spice it a little with new multi billion tunnels and junctions. i thought it might eek out a few more fanciful ideas. Sometimes simple solutions can be arrived at by a mad suggestion.

One of the options mentioned locally a number of years ago was a by-pass. Surprised that hasn't been mentioned seriously here. Double decking the viaduct was another option. I'm sure there were more. I'll try and find the website with them all listed.

PS - I still think sending 4tph around the loop is both cheap(ish), practical, quick to do and unlikely to upset the 'green' brigade. Only needs a few signals, extra power points and a few yards of track at Gordon Hill.

Found it - look here http://www.rail-net.co.uk/bottleneck/the_plans.htm

 

[tbtc]

PS - I still think sending 4tph around the loop is both cheap(ish), practical, quick to do and unlikely to upset the 'green' brigade. Only needs a few signals, extra power points and a few yards of track at Gordon Hill.

What's the time penalty for using the "loop" compared to the main line?

(in terms of stoppers and in terms of fast trains)

 

[Lee_Again]

What's the time penalty for using the "loop" compared to the main line?

(in terms of stoppers and in terms of fast trains)

Just after the Hatfield accident all trains went via the loop. The slows were removed with bus connections to other stations. The time penalty was about 7 miunutes.

More recenlty the time difference can be less than 5 minutes with a clear run. Adding this time to the non-stop Cambridge and Finsbury Pk>Stevenage services is a small price for 4 new paths across the viaduct/tunnels.

The problem is not so much the time penalty. It's just impossible to have both slows and fasts. It's only two track with no passing points.

That's why I/others have suggested putting loops in at Gordon Hill. The platforms are already configured in the correct pattern. Further, extra power is needed as the current system does not support any additional trains.

The signal spacings are also not great (for fast running) with some very long sections north of Hertford to Langley Jn (where the loop meets the ECML).

 

[jon0844]

Isn't the Hertford Loop being used now/soon to test new signalling? Upgrade that and create some passing loops and it's surely worth doing whatever happens along the ECML? Trains closer together, able to run faster etc..

In fact, is there any other station (or in between two stations) that could allow for passing loops to allow an additional overtake for what might eventually become a more regular all-station service (whether part of LO or not)?

 

[silverfoxcc]

Just off on a tangent, but the quadding of Coppermill-Broxbourne is going to be a very hard ask as a lot of the old trackbed to Picketts Lock ( where it ended previously) is built on esp Tottenham Hale, and room is a premuim north of there

 

[Rick1984]

The problem with this is that the viaduct is listed. The view of the viaduct from one side is protected from any development but the other side is where most of the adjacent property is so would affect at lot more local residents as their properties would need to be demolished.

I see the problem there. I thought it was just the old mentality of "you can't put something new there!" When actually a new structure can often work will with the old if done right.

 

[jon0844]

There's a simple solution.. start to do some route maintenance work to the bridge and then, whoops, blow it up by accident!

 

[Cliveblackpool]

I see the problem there. I thought it was just the old mentality of "you can't put something new there!" When actually a new structure can often work will with the old if done right.

True. A suspension bridge could compliment it, and not block the view?