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Post by Deleted on Nov 19, 2010 18:56:10 GMT
They are black, circular and have an illuminated orange light in the centre that glow in the dark when in the tunnel. Noticed them on my way home from work today and wondered what their purpose is. Cheers.  |
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Post by Deleted on Nov 19, 2010 19:58:47 GMT
They are black, circular and have an illuminated orange light in the centre that glow in the dark when in the tunnel. Noticed them on my way home from work today and wondered what their purpose is. Cheers. There's a lot of surveyors' type equipment set up at the moment to do with the station upgrade. Could be to do with that. |
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Post by ibus on Dec 5, 2010 18:06:27 GMT
They are black, circular and have an illuminated orange light in the centre that glow in the dark when in the tunnel. Noticed them on my way home from work today and wondered what their purpose is. Cheers. There's a lot of surveyors' type equipment set up at the moment to do with the station upgrade. Could be to do with that. Yes, they are at Tottenham Ct Rd, Bond St and London Bridge too  |
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Post by Deleted on Dec 5, 2010 18:19:00 GMT
There's a lot of surveyors' type equipment set up at the moment to do with the station upgrade. Could be to do with that. Yes, they are at Tottenham Ct Rd, Bond St and London Bridge too I think I've seen them at just about every deep-level station I've ever been through. |
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Post by ibus on Dec 5, 2010 20:07:08 GMT
Yes, they are at Tottenham Ct Rd, Bond St and London Bridge too I think I've seen them at just about every deep-level station I've ever been through. You'll see them at the majority of those which have planned or ongoing building/construction work at ground level e.g. The Shard, Crossrail stations & Victoria Station rebuilding works |
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Post by Deleted on Dec 5, 2010 22:15:27 GMT
Yes, I think they're there to detect and report any movement of tunnels that might occur during major building works.
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Post by londonstuff on Dec 5, 2010 22:46:07 GMT
Yes, I think they're there to detect and report any movement of tunnels that might occur during major building works. Yup, that's correct. There's also a note about them at the headwall of one of the Heathrow terminals relating to the ongoing building work there - they detect any movement, etc. I believe in the case of Victoria, they're there earlier so they can see what 'normal' movement is like there - data gathering in other words. |
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Post by railtechnician on Dec 7, 2010 0:19:57 GMT
Yes, I think they're there to detect and report any movement of tunnels that might occur during major building works. Sounds like purpose built equipment, a step on from what I recall being used at the Bank/Monument upgrade 20 years ago or thereabouts. Back then movement detectors were linked to an alarm system with flashing blue beacons and 100dB sounders throughout the impacted areas. I also recall the standard glass plates fitted to indicate amount of movement where the cracks appeared as seems to be basic standard practice for subsidence monitoring in civil engineering. |
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Post by mcmaddog on Dec 7, 2010 10:25:53 GMT
They really are ugly things as ceiling panels are always missing around them. They make ceilings look terrible.
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Post by Deleted on Dec 20, 2010 15:38:34 GMT
There's quite an interesting array of these survey markers and theodolites along St Thomas' Street and other surface structures surrounding The Shard, lots of them in the tunnels under the London Bridge station viaduct.
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