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Oxted tunnel - should this be singled

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Failed Unit

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https://www.railforums.co.uk/threads/171’s-leaving-southern.218587

taken from above. Should the Oxted tunnel be singled to allow more rolling stock flexibility.

further posts say that the timetable is too intense.
 
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hwl

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could it be made single line or would that make the timetable impossible. If I recall that is what they did with Tonbridge to Hastings to electrify it.
8tph in each direction... So no.

The timing through there has to be as flexible as possible or both the Southern and the Thameslink timetables (inc MML and ECML) don't work.
 

CBlue

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could it be made single line or would that make the timetable impossible. If I recall that is what they did with Tonbridge to Hastings to electrify it.
I hope you're not suggesting that the tunnel be made single line just so Sprinters can fit! :lol:
 
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JonathanH

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I hope you're not suggesting that the tunnel be made single line just so Sprinters can fit! :lol:
Is there anything to say that 156s wouldn't fit? They have a slightly more narrow body profile than some other units because of their 23m length. Clearly 20m 377s, 700s and 23m 171s fit so I don't know what rolling stock issue is trying to be solved that necessitates making the line single (which would be a bad idea as already noted).

From the other thread
The loading gauge in the Oxted tunnel* is very restricted so mk3 (including 20m Mk3 stock e.g. 319/ 455/456s) or equivalent based stock including sprinters won't fit

*Defines the vehicle width and end taper on Electrostar, Turbostar, and Desiro City rolling stock - which is funnily enough what you are limited too (20m Aventra should be fine too)
So even though the 23m Turbostar fleet wasn't initially ordered for Southern, the early 168s (in 1996) and 170s were designed to fit Oxted Tunnel on speculation there would eventually be a Southern order?
 
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RobShipway

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Short answer to the question is no, Oxted Tunnel should not be made single track. There is enough of the line that has been made single track already.
 

Failed Unit

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To be honest when you see todays problem it doesn't make any sense. I can see why the mk3 stock doesn't fit as it is wider. But the Electrostar's do so to solve todays problem electrifying the rest of the line and using the electrostar's does seem to solve todays problems. If they don't have enough then we have enough 3rd rail stock about to go to the breakers, or they can build more for lines where the loading gauge isn't as restrictive to free up the Electrostars for this line.

The future I guess the can specify the rolling stock must fit this line, they have done it before. But if that makes a non-standard expensive build they may need to look a that again. But I guess that problem is at least 20 years away on this line.
 

zwk500

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The other tunnel on the Ukfield line is called Grove Tunnel which is even narrower and is formed of single track.
See https://media.subbrit.org.uk/10295/1552690184-csearly80s.jpg?fm=jpg&auto=compress
Grove tunnel isn't on the Uckfield line, it's on the Tunbridge Wells Central to Tunbridge Wells West line and is now closed. It was always single track.

There are other tunnels on the Hurst Green to Uckfield line, of which 3 are double track and 1 is single, but the entire line was double track throughout (Mark Beech Tunnel is single, Little Browns, Edenbridge, and Crowborough tunnels are not). Oxted Tunnel is north of the Junction of the Uckfield and East Grinstead Lines, so carries greater traffic than any of the 4 on the Uckfield line alone. Therefore it is not viable to single it.

However that doesn't really apply to this discussion because none of them have the problems identified by @hwl, who's post in The thread referred to in post #1 makes it clear the issues with Oxted Tunnel in particular:
For the Nth time:

The loading gauge in the Oxted tunnel* is very restricted so mk3 (including 20m Mk3 stock e.g. 319/ 455/456s) or equivalent based stock including sprinters won't fit.

*Defines the vehicle width and end taper on Electrostar, Turbostar, and Desiro City rolling stock - which is funnily enough what you are limited too (20m Aventra should be fine too)

Digging from the 2 ends didn't align when they met in the middle so it was fudged with a set of reverse curves:

View attachment 98143
Photo from Adrian Backshall http://momodem1.blogspot.com/2015/08/a-walk-through-oxted-tunnel.html
The only way it will be sorted is if a new single-track bore is dug to permit the old tunnel to be singled. At the moment, there's no need to do this as existing stock fits through it, and there are other more restrictive tunnels on the network to worry about.
 

RobShipway

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To be honest when you see todays problem it doesn't make any sense. I can see why the mk3 stock doesn't fit as it is wider. But the Electrostar's do so to solve todays problem electrifying the rest of the line and using the electrostar's does seem to solve todays problems. If they don't have enough then we have enough 3rd rail stock about to go to the breakers, or they can build more for lines where the loading gauge isn't as restrictive to free up the Electrostars for this line.

The future I guess the can specify the rolling stock must fit this line, they have done it before. But if that makes a non-standard expensive build they may need to look a that again. But I guess that problem is at least 20 years away on this line.
The problem is at least 20 years away and within that time other solutions will present themselves such as trains like the Coradia iLint currently on test in Europe.

If you read any Network rail documentation on decarbonating the network, many say that there is finite capacity on many lines. By making Oxted Tunnel single track, you are making that capacity even finer.

There is no need to be paying extra cost, if as Hwl has pointed out there is existing newer stock based on the 20m Aventra that should fit. But if you did single track the existing Oxted tunnel, as Zwk500 has stated you would need to be creating a single track bore, so that the current capacity could be maintained. Depending on the costings, but you may find that changing the Infrastructure costs you more than buying a fleet of trains off the shelve, that can cope with using Oxted Tunnel in it's current state.
 
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