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Cowburn Tunnel edit
Not clear what there was to flood to 30m... was it the airshaft perhaps?
- It flooded the header. They drilled a header shaft and worked outwards. At Totley they drilled seven.
And the rising line - was it to avoid going into the unstable shale? (I dimly recollect this was a problem at Woodhead?)
- It may have been but my reference didn't say, just gave dimensions.
I'd assumed it was limestone, and also with Totley (I remember it as Dore and Totley like the station) and the water was from springs. The tunnels are each end of the Hope Valley, so my assumption was, they were limestone outcrops around the shale in the valley. I'll have to ask a geologist. Chevin 22:00, 1 October 2005 (UTC)
- The Totley tunnel was cut through a mixture of shale, coal and ganister deposits and probably Crawshaw sandstone, which itself is fairly fragile. I'm still trying to find out about Cowburn. Chevin 13:13, 14 October 2005 (UTC)
Unclear edit
The bit about the flooding isn't clear. A response above states that they drilled a header shaft and then worked outwards. But the article itself talks about the headings meeting, which sounds like they worked inwards from either end. Which is correct? --David Edgar (talk) 22:33, 30 January 2017 (UTC)
- Both: tunnels are almost always dug from the ends, in addition to headings from any shafts that may have been sunk. So for a tunnel with one working shaft, like Cowburn, there would be four headings and two meeting places. --Redrose64 🌹 (talk) 00:31, 31 January 2017 (UTC)
- OK, that seems to make sense, thanks.
- But I also wonder, when it says "work was carried on in a diving bell", can any sort of productive digging work be done by someone in a diving bell? --David Edgar (talk) 01:22, 1 February 2017 (UTC)
- Maybe not a literal diving bell - perhaps it means that some sort of pressure wall was used, as with the Severn Tunnel. It's unsourced, so I don't know where the claim originated, so I can't check. Maybe Chevin (talk · contribs) can clarify. --Redrose64 🌹 (talk) 09:52, 1 February 2017 (UTC)