Thursday, 31 July 2008

The Thameslink Programme, illustrated

There are lots of elements to the Thameslink Programme, but at its core is a proposal to untangle the lines outside London Bridge to get the maximum possible number of trains through as efficiently as possible.

As an introduction, here's how things currently work (click to enlarge):
[NB pedants: this is a simplified schematic showing the principle of the thing, not a track map, though it doubles as one in places]
The worst problems are highlighted in red:

  1. Thameslink trains through London Bridge have to cross in front of Southeastern services terminating at Blackfriars. There's also a short section of single track due to cost cutting before the Thameslink service was introduced.
  2. Borough Market Viaduct. A huge number of different services have to share this double track bottleneck, as well as the London Bridge platforms that serve it.
  3. To get onto the route towards Borough Market Viaduct, Thameslink trains need to make a flat crossing move.
  4. It's fairly common to have a pair of fast tracks between the two tracks used by stopping services, but normally there's a flyover provided near the terminus to switch them out. At London Bridge there is no flyover, so trains just cross the southbound slow line.
  5. Tanners Hill flydown. This link was built relatively recently to allow the bridge taking trains to Victoria* to double as a flyover to get trains onto the fast lines to London Bridge without crossing the slow lines. Currently only single track.
If you follow the route of Thameslink trains through London Bridge (dotted purple), you'll notice they share track or otherwise conflict with almost every other service in the area, which is why they don't run during peak hours. Given that London Bridge is going to be the principal Thameslink route when the programme is finished, that isn't a good start.

Here's how they intend to fix it:
  1. Rebuild Blackfriars to have the through tracks to Farringdon on the same side as London Bridge. The knock-on effect is that services from the Wimbledon/Sutton loop will now be on the wrong side to run through, so will terminate at Blackfriars, and services from southeast of Elephant & Castle will run through instead.
  2. Build a second pair of tracks over Borough Market. London Bridge will also be rebuilt with extra through platforms.
  3. The Bermondsey Diveunder. This is a massive piece of engineering due to the number of viaducts that need to be reworked. Its basic purpose is to get Thameslink trains to/from the Brighton direction over the top of the Southeastern tracks to/from Charing Cross.
  4. The southbound slow line is also routed under the dive under, and no longer crossed by other services.
  5. Double tracking the Tanners Hill Flydown. There aren't going to be many Thameslink trains going this way, but it's still part of the project.
The second diagram also illustrates how the East London Line extension fits in (with phase 2 dotted), and incorporates proposals from the South London RUS (chiefly evicting everything but Southeastern fasts from Charing Cross).

[* The "temporary" replacement bridge built after the 1957 Lewisham Rail Crash, in fact]
[Thanks to Paul Scott for forwarding me the documents used to draw this]


Anonymous said...

Typical shoddy lack of foresight by the Victorians. Hurrah for British Rail's Thameslink 2000 scheme to drag the network into the 20th century at last.

How on earth have we managed without it for so long?

Dan said...

Fantastic - thank you for laying it out so clearly. Now it all makes sense!

(In a moment of pedantry, should the arrow on the link from the Blackfriars down to the Canon St down be pointing the other way?)

Pedantic of Purley said...

And more significantly you seem to have entirely missed out the No 2 reversible line serving London Bridge No 2 platform to a point just to the east of New Cross.

Of course you could argue that the diagram was highly schematic and not intended to include everything (all the detail at Cannot Street or every set of points for example).

Anonymous said...

I think it's clear and excellent - ignore them!

Will it result in any quicker journey times (always maintained LB to LGW was quicker than Victoria) or just less waiting at LB?

THC said...

You want pedantry? In your explanatory note to the diagram I think you mean "principle" as opposed to "principal".

That's pedantry. :-D


Mr Thant (Editor) said...

Dan: Correct, fixed, thanks.

Pedantic of Purley: For the purposes of this diagram that line is functionally equivalent to the lines shown.

THC: Fixed. Thanks

Mark Boulton said...

You wouldn't believe how many companies I've worked for that believe they are the "Principle Contractor" or that they have a "Principle Design Engineer".

Just as well. I assume without them we would have no morals left ;)

Michael Abrahams said...

May I point out that the South London Line will not go to Clapham or Victoria, the ELL phase 2 will use this route to Clapham Junction but not Victoria. However, South Central train services (it would be incorrect to assume that the will be run by Southern Railway in 2015) will go on to Tulse Hill.

You should add that ELL trains to Sydenham will go to West Croydon and Crystal Palace (not to Gatwick or Brighton).

What does the grey line signify joining the up line from New Cross Gate to the green down line from London Bridge?

Paul Scott said...

michael - the grey line you refer to appears to stay in place, and allows for the possibility of reversing ELL trains at NXG (like when LU ran it), probably for use during engineering works, main line problems, or perhaps even at the start/end of service.

Mr Thant (Editor) said...

Michael: It's the redundant second track left after the slow line is diverted under the dive under. I probably shouldn't have left it on, but oh well.

Anonymous said...

did someone famous not once say a picture is worth 1000 words, in two pics, you've done the best job of explained the Thameslink 2000 scheme I've seen yet!

D-Notice said...

These diagrams are really helpful.

Any chance of adding them to Wikipedia's article the Thameslink Programme?

Greg said...

You seem to have created a Blackfriars without any Southeastern services?

Mr Thant (Editor) said...

Greg: Yes! See point 1. Because the through lines and terminus platfomrs are switching sides, it's going to make more sense to run trains from Southeastern territory into Thameslink, and trains from Southern territory (Wimbledon/Sutton) into the terminus platforms.

Dave said...

Great way of explaining a very complicated programme of works.

Small point: whilst not many Thameslinks will be going via Tanners Hill flydown, it's still vital for the Programme because it mitigates the impact of the programme on Southeastern (which would otherwise have more trouble robustly running Metro services to and from Charing Cross).

Anonymous said...

That's a great explanation of whats happening!

I suppose that this area is one of the most complicated parts of the network in London, but it got me thinking about how many other such "pinch-points" there might be on the network that would provide great benefits if fixed...!