Stalactites on side and roof of tunnels.

[longhedge]

I have the whole suite of Video 125 `Driver`s Eye Views` and I have noticed what appear to be `clamps` between the tunnel rings of various shapes / sizes along a good proportion of the tunnels, mostly in the roof and high up along the sides.
 Particularly noticeable on the Piccadilly Line Video. Are they there to maintain integrity of the tunnels? Stop water ingress? Does anyone know?

[brigham]

Clamps? Not Stalactites.

[longhedge]

Jan 29, 2015 12:25:13 GMT brigham said:

Clamps? Not Stalactites.

I should have been more clear. They look a bit like stalactites on the video but wider.

Apart from Victoria Line, they appear on all other lines. I`m hopeful tube drivers know what I mean. You cannot miss them. But I really don`t know how to describe them better. I am talking about a metallic objects here.

[John Tuthill]

Jan 29, 2015 20:16:58 GMT longhedge said:

Jan 29, 2015 12:25:13 GMT brigham said:

Clamps? Not Stalactites.

I should have been more clear. They look a bit like stalactites on the video but wider.

Apart from Victoria Line, they appear on all other lines. I`m hopeful tube drivers know what I mean. You cannot miss them. But I really don`t know how to describe them better. I am talking about a metallic objects here.

In the "The Hampstead Tube-A history of the first 100 years" (Capital Transport) on page 102 there is a photograph of track being laid between Highgate and east Finchley. The track is suspended from the roof of the tunnel,on a clamp and parallel guide rail, the rails utilising the 'Brogden Joint' a half butt joint, which I must admit I've never seen before. Hope this helps.

[Chris M]

There is an illustration of a Brodgen Joint in this google books page and a photograph of one in the NRM's collection here.