Suggestions for where new flyovers/diveunders should be built to replace 'flat' junctions

[bringbackcrouc]

If you could pick any flat junction across the whole country to replace with a flying junction, which one would you go for?

My opening gambit would be... something immediately north of Lewisham.

I look forward to being disabused to the notion that this is the most pressing case across the whole country.

 

[Taunton]

Woking. Newark. Colwich. Didcot East. Having them on 100/125 mph lines seems more relevant.

I'd go for Didcot East purely because I seem to be badly delayed there on about 50% of all movements, especially from the Down Main to the Oxford avoiding line.

 

[backontrack]

Newark.

 

[Starmill]

Wouldn't Newark be a flyover rather than a flying junction? Or does the OP mean just any new instance of grade separation that currently doesn't exist?

 

[bringbackcrouc]

Wouldn't Newark be a flyover rather than a flying junction? Or does the OP mean just any new instance of grade separation that currently?

I do indeed.

 

[70014IronDuke]

Woking.
But it's 'orribly difficult.

 

[Lucan]

Woking.
But it's 'orribly difficult.

Another Woking vote, and I don't see why it should be too difficult. There is about 800m between the west end of the platforms and the junction for Portsmouth, about the same as the length of the ramp north east of Wimbledon where the up slow line crosses over the fasts.

 

[AlterEgo]

Woking.
But it's 'orribly difficult.

Woking is an obvious one for me, as well as Colwich.

 

[MidnightFlyer]

Woking. Didn't large swathes of the 2004 South West recast have to be written around getting it to work there first?

 

[The_Engineer]

Euxton Junction, Up and Down Chorley to Up and Down Slow to avoid main line conflict.

 

[MarkyT]

Another Woking vote, and I don't see why it should be too difficult. There is about 800m between the west end of the platforms and the junction for Portsmouth, about the same as the length of the ramp north east of Wimbledon where the up slow line crosses over the fasts.

I agree it's not particularly difficult technically, but it would be very expensive and disruptive to construct no doubt, requiring a near complete reconfiguration of the entire junction at the west end. Perhaps paradoxical to many, being the ONLY flat junction along the route actually makes it fairly easy to manage as well, and the slow line service from the London direction in particular has already thinned out massively before Woking is reached. I think it will be new service patterns such as possible Heathrow southern connection flows that could precipitate this large investment and ideally it should be timed to replace a scheduled major renewal of local junctions so the renewal money can contribute towards the better overall solution. An additional through platform, for flexibility and better real time regulation is at least as, if not more important than grade separation at Woking.

 

[MarkyT]

Woking. Didn't large swathes of the 2004 South West recast have to be written around getting it to work there first?

It's standard practice for TT planning to solve major conflict points first I believe.

 

[MidnightFlyer]

It's standard practice for TT planning to solve major conflict points first I believe.

Indeed, but I was led to believe Woking provided a particular headache. Four conflicts an hour and all that, then having to make that work once you get closer to London.

 

[bringbackcrouc]

Woking appears to be winning the argument at the moment; any naysayers?

 

[DidcotDickie]

Woking. Newark. Colwich. Didcot East. Having them on 100/125 mph lines seems more relevant.

I'd go for Didcot East purely because I seem to be badly delayed there on about 50% of all movements, especially from the Down Main to the Oxford avoiding line.

I'd agree that Didcot East is a contender. Now that Reading has been sorted out it must be the biggest bottleneck on the GWML.
Two trains per hour from down main to down avoider (down Oxford fasts - more if any XC are routed on the mains) conflict with up fasts from Swindon and anything on the reliefs then two in the opposite direction from up avoider to up main conflicting with the reliefs.

I don't know Woking but as that's the only major flat junction on the SWML east of Basingstoke and handles traffic off the Portsmouth Direct line, though I reckon they must both be contenders.

 

[Dr Hoo]

What about some busy fast <-> slow weave locations on four-track routes paired by use? I am thinking of locations such as Ledburn and Harpenden. Especially as the mix of rolling stock with different speed capabilities (125, 110, 100, tilt/non-tilt, bi-mode, freight, etc.) seems to get ever more complicated.

 

[Mikey C]

This will never happen, and almost certainly could never happen due to lack of space (never mind the expense), but I'm put love to remove all the flat junctions on the Circle Line.

Just picking one, a flying junction east of Baker Street so that west bound Metropolitan line trains can access their platforms at Baker Street without crossing over would definitely help increase capacity and enable more H&C trains to run.

 

[Taunton]

The thing about Baker Street, and to an extent Lewisham, is that the conflicting trains involved are effectively making a standing start and can have close overlaps. You can see in any peak hour two eastbound Circles in close succession, and getting a westbound Metropolitan across between them without impact.

At Didcot East a westbound Oxford express ties up all four through lines as it crosses over and requires a considerable eastbound 125mph approach buffer. The modern-days ladder also ties it all up over a considerable length, and, if the service has been checked, for a considerable time. The slowing down also impacts following capacity on the Down Main. Up freights which have just made it to Didcot and onto the Up Relief ahead of a 125mph service can commonly be in this mix as well.

 

[Highlandspring]

Newbridge, Hyndland East, Portobello.

 

[swt_passenger]

I agree it's not particularly difficult technically, but it would be very expensive and disruptive to construct no doubt, requiring a near complete reconfiguration of the entire junction at the west end. Perhaps paradoxical to many, being the ONLY flat junction along the route actually makes it fairly easy to manage as well, and the slow line service from the London direction in particular has already thinned out massively before Woking is reached. I think it will be new service patterns such as possible Heathrow southern connection flows that could precipitate this large investment and ideally it should be timed to replace a scheduled major renewal of local junctions so the renewal money can contribute towards the better overall solution. An additional through platform, for flexibility and better real time regulation is at least as, if not more important than grade separation at Woking.

Only flat junction apart from Basingstoke, Eastleigh, St Denys, Redbridge, Guildford, Havant? Depending on how you define ‘the route’ of course...

 

[The Planner]

Woking. Newark. Colwich. Didcot East. Having them on 100/125 mph lines seems more relevant.

I'd go for Didcot East purely because I seem to be badly delayed there on about 50% of all movements, especially from the Down Main to the Oxford avoiding line.

Would agree with all four-ish, Colwich is a harder sell though I think, as its only 2tph.

 

[XDM]

Woking.
But it's 'orribly difficult.

I don't think it is. The Southern railway had detailed plans for a Woking flyover. British Rail inherited them & improved them.
The plans with I in 70 uphill & I in 50 down should be dusted down & implemented.
I have seen it said that some rail land has been sold by that friend of the railway, Network Rail. But I can't see where.
And in any case gradients could be increased to I in 40 up & I in 30 down to reduce the land take. Freight is much less now & could go on the level. Woking flyover please.

 

[bringbackcrouc]

Has anyone got a spare £100m?

http://www.oxfordmail.co.uk/news/14...ay_could_be_built_to_deal_with_future_demand/

 

[MarkyT]

Only flat junction apart from Basingstoke, Eastleigh, St Denys, Redbridge, Guildford, Havant? Depending on how you define ‘the route’ of course...

Fair enough. Maybe better to refer to it as the first flat junction encountered going west from London. I'm not arguing against it, or the undisputed fact Woking is 'full' today but I will stand by my comment that it will be service growth such as new Heathrow services that justify its grade separation in the future with hopefully an additional platform as well. Here's my layout idea, slightly different to the NR route study sketch.

 

[ccityplanner12]

Colwich is on an underbridge, which rules out a diveunder, but it could have a really smart flying junction, with the down avoiding on a viaduct above an island platform between the main lines. The problem is rerouting the A51.
This would have happened instead of the Bakerloo line extension if I'd have been in charge of New Works.

 

[LNW-GW Joint]

Woking is an obvious one for me, as well as Colwich.

Colwich will be irrelevant when HS2 reaches Crewe (which should also sort out Crewe itself).
Didcot is a good pick for a flyover.
We'll soon see if the Ordsall Curve really should have been grade separated from Day 1.
Edgeley is also a real problem at Stockport, from the Sheffield direction.
Trent-Long Eaton is a pig as well.
Improving Bordesley-Proof House would be nice, too.
All more important that a flyover at Peterborough (IMHO).

 

[Kite159]

East of Basingstoke with the Reading line. Mainly for freight trains & the XC services

 

[InOban]

Newbridge, Hyndland East, Portobello.

Absolutely. Particularly Hyndland East. 14 trains per hour, each way, every hour, over a flat junction!.

 

[Ploughman]

Skelton Jn North of York.
Take the Up Slow over the Fast lines.

Leeds - Something to take the Up and Down lines from Kirkstall to Holbeck over/ under / round Whitehall jns

 

[tbtc]

A couple of early votes for Newark, but the current service actually crossing over the ECML is only one passenger one per hour (generally a two coach DMU) plus a very small amount of daytime freight. Yes, a flying junction would permit more passenger services, but we have enough problems dealing with the practicalities of congestion at existing bottlenecks before we have money to spend on the "if you build it they will come" stuff.

Down south, Woking and Didcot both seem good shouts to me - give how busy existing lines are and how many passengers per hour are potentially inconvenienced by such bottlenecks.

North of the border, Hyndland East would be a good one to fix (probably the most pressing one in the UK), maybe the flat crossing at Motherwell too?

North of England, I'm wondering about Doncaster. There are currently three passenger services per hour from the Conisbrough line to the Kirk Sandall line (Sheffield to Hull, Scunthorpe, Cleethorpes), so six services crossing the ECML on the flat. Now that so few of the Scottish services stop at Doncaster, it probably affects how easy it is to schedule "Provincial" services crossing between "InterCity" services. Maybe something south of Manchester Piccadilly to sort out the Airport/Stockport split at Slade Lane?