Between Bank and Moorgate...

When CSLR sees this thread he will put forth another excellent monologue on the history of this part of the Bank Branch, but to make the long story short, the tunnels 'roll over' each other south of Moorgate, and 'roll over' each other again near Borough. This was done because this part of the Northern originally terminated at King William Street, and to reach this terminus, the tunnels 'rolled over' to increase the radii of the curves required.

The Central Line does something similar west of Shepherd's Bush.

You are all doing pretty well so far and getting reasonably warm with your answers.
As TOK suspects, the real story is a little stranger than most people might imagine. Keep the theories coming and I will fill in the missing details tomorrow night.

I think you may find that it is a lot stranger than that
Also the choice of cable traction was vital. If they had not chosen that when they did, the line would almost certainly not have been constructed at that time. Greathead's deal with the Patent Cable Tramway Corp effectively bankrolled the project.


Perfectly true and a contributory factor in the wrong line running story. But which section of road caused the problem?

TheOneKEA replied:[/b]



Correct. But why did thats cause wrong line running?

When Greathead started constructing the C&SLR, he had to face a belief expressed by several prominent engineers that London Bridge would fall down if he tunnelled too close to it. Greathead therefore decided to build the controversial under-river section first.
He started work by sinking a shaft in the river just off of Swan Lane, from where he planned to start construction of the tunnels one above the other. This arrangement was necessary because there was no statuatory authority to pass beneath buildings. Swan Lane was the only suitable road that ran down to the north bank of the river, but was not wide enough to allow the tunnels to run side-by-side, so they had to be stacked on top of each other at that point. As a bonus, it saved him the problem of having to sink two shafts in the river.
From Old Swan Shaft, he proposed to build his tunnels out beneath the Thames, knowing that his two biggest challenges were:-
1. Constructing the closer of the two tunnels to London Bridge (because of the danger of damaging the bridge).
2. Constructing a tunnel too close to the bed of the river (because of the danger of the river breaking into the works, as experienced by Brunel in the Thames Tunnel).
To get both of these issues out of the way, he built the upper tunnel first (starting October 1886) and dropped it down to pass beneath the deepest point in the river bed. He also decided to make this the closest of the two tunnels to London Bridge. This meant that the most difficult part of the construction was the first to be completed. When the second tunnel was started in February 1887, it had to fit into the space between the first tunnel and the eastern limit of deviation (the ‘limit of deviation’ is a legal boundary approved by parliament beyond which the railway may not be constructed).
With the under-river tunnels complete, Greathead turned round and prepared to build the line towards King William Street. After passing one above the other along Swan Lane, the lines ran along Arthur Street West and had to align themselves side-by-side very quickly before entering King William Street station. This meant that the lower tunnel had a steeper climb into the station than the higher one.
The company chairman, Charles Grey Mott, did not favour cable traction and was already considering some form of powered locomotion, so it did not make sense to create an approach gradient that was steeper than necessary. It was therefore decided to make the higher tunnel the up (northbound) line, as this would give a more gentle - though still very steep - climb for trains entering King William Street station. The lower tunnel, with the crippling 1 in 14 rise became the down (southbound) line. In the end, that was exactly the right decision, as the electric locomotives had enough trouble with the 1 in 29 - an even steeper climb would have been virtually impossible for them.
So, by becoming the up line, the higher tunnel created a dilemma. Because it had been constructed closest to London Bridge when passing under the Thames, the running direction was the reverse of normal. To put the lines back in the right place, they were finally reversed by passing the down line beneath the up line between Borough and Elephant & Castle stations. Few staff and passengers realise that Borough is wrong way working, because this fact is totally concealed from them by the split level layout.
When the extension to Moorgate Street was built, it was decided to flip the lines back again. After breaking away from the old line north of the Borough, the tunnels had to drop down to pass beneath the original tubes. In order to keep the gradients under control, it was not possible to cross the lines back before London Bridge station. After London Bridge, the lines tackled the river and had to remain at a deep level to pass beneath the brick tunnel of King William Street station. After that there was not enough space to flip them over before they entered Bank station. The lines therefore crossed back between Bank and Moorgate Street.

A couple of points:-
1. Greathead was very much a seat-of-the-pants engineer and appears not always to have worked things out fully in advance. This is clearly demonstrated by his evidence to parliamentary committees when applying for authority to construct a line. When asked how he was going to do something, he appeared to make things up only to change them after giving the matter some thought. This does not mean that he was a bad engineer, it seems just to have been a case of, ‘We will solve that when we get to it’. That quote, incidentally, was not from the mouth of Greathead, just in case anyone reads this and thinks of attributing it to him (one of the problems of the internet!)
2. The C&SLR always planned to have a station at London Bridge, but it was never built on the original line due to a dispute with a main line company over the provision of a covered way.
3. The original layout at King William Street was a single track terminus as necessitated by cable operation. This was later converted to a two-track island platform. Stockwell was built after the decision was made to use electricity and so always had a two-track island platform layout.
4. Although parliament would not pass an Act allowing the C&SLR wayleave beneath buildings, the company reached a private agreement with the owner of Hibernia Wharf to pass beneath a corner of their building. This was the only way to get the tracks back beneath a highway on the south side of the river.
I do not think that anyone has ever pointed out that the tunnels actually diverge from their permitted line of deviation at this point and actually pass beneath a larger part of the building than the 'corner' that Greathead suggested.

Well that's confirmed something for me.... I always thought Bank was the wrong way round - now I know it is, and the reason why

I can probably put some plans up, if you will bear with me for a couple of days. I will try to digitise what I have, but it will take a little work to make them readable in a smaller scale.

Wow what a great reply from CSLR! I can't wait for the plans!
Which tunnel goes above the other though?

On a side note seeming as we're speaking of the Bank branch, why does no-one take interest in the echoing cavern of City Road as the train passes it? Would this station ever be reopened?

I'd say City Road would make a useful addition, Old Street is quite a slog away, and Angel is uphill and round the corner... Theres a lot of flats around the station, but is served rather well with buses... would be nice to see it re-opened, bit I guess on the same vein as York road, costs would be astronomical...

Yep! Both ways!

I would imagine LU are kicking themselves for not installing an MIP lift. It obviously wasnt seen as a priority back in the early 90s.

Old St is very busy in the peaks. When I travel, most seem to alight at Kings X.

The old surface building still exists though, I walk past it everyday. If both were open, all that is needed is a quick walk (could be signposted) through Angel Square.

My dad works for Viacom (previously worked on the Connect project before being made redundant lol don't maime him) so he has access to plans. Ive seen an Angel one before made by Tube Lines. According to the plans, the old lower concourse still exists. The only thing that would be required for any access is to re add stairs. Defeating the object of course for wheelchair access.

Anyone remember the old Wadsworth lifts at Angel. A blue moon occured if they were both working correctly!

yay, I'd love to see these!

xx AngelIs

Yup, sure does clear up a lot of misunderstandings in a way a description never could. Thanks again.