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Post by jamesb on Jun 24, 2007 20:28:35 GMT
On the eastbound Piccadilly line platform at King's Cross there is a machine on the ceiling that moves about like a robot and points at various targets sticking out the walls.
Does it record data which can be downloaded and analyzed to check for movements of the walls? Is this a particularly big problem at King's Cross, since I haven't seen these machines at many other stations?
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Post by Deleted on Jun 24, 2007 20:36:01 GMT
Probably summat to do with the erstwhile CTRL construction work thats going on... where abouts is it on the EB platform? Not noticed it myself...
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Post by Deleted on Jun 25, 2007 0:39:59 GMT
I have seen the reflectors on one of the Northern Line platforms, but not the robotic machine. I would agree with Mr Artery that it to observe any movement due to the various construction works going on at Kings X.
Or maybe it's a laser gun to zap people who obstruct doors?
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Post by Deleted on Jun 25, 2007 5:50:34 GMT
They also have them mounted to the tunnel walls between Baker Street and Great Portland Street, with reflector type things mounted on sleepers. They popped up after the BTR down there, probably measuring track movement.
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Post by edb on Jun 25, 2007 5:52:50 GMT
There also happens to be one in the main roof of Kings Cross itself.
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Post by Chris M on Jun 25, 2007 11:55:02 GMT
They also have them mounted to the tunnel walls between Baker Street and Great Portland Street, with reflector type things mounted on sleepers. They popped up after the BTR down there, probably measuring track movement. What is "BTR" in this context? |
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Post by c5 on Jun 25, 2007 13:27:58 GMT
Ballasted Track Replacement.
In know Tom knows all the other older names ;-) As he has put them on here before!
Its the stuff that the Infracos claim to do every now and then!
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Post by Deleted on Jun 25, 2007 16:29:15 GMT
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Post by jamesb on Jun 25, 2007 17:54:20 GMT
Probably summat to do with the erstwhile CTRL construction work thats going on... where abouts is it on the EB platform? Not noticed it myself... But it's been there for as long as I can remember... It doesn't look like a recent addition. It's on the ceiling near the front of the eastbound platform, about two cars back. You can hear it zzzzzz'ing as it moves around and points at the different targets sticking out the wall. |
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Post by stanmorek on Jun 26, 2007 21:09:46 GMT
Its some kind of Total Station monitoring system sometimes called an EDM (electronic distance measurement). I recall someone pointing it out to me as far back as 2003 when the Western Ticket Hall was being built but yes its for the CTRL works.
We used something similar at Southfields tunnel. The EDM automatically measures the distance and the angle of line of sight of a small prism in each target. It was left overnight during a weekend possession and linked to a pager and would send an alert if any deviations over threshold levels were measured.
The first time a BTR was carried out in a tunnel section was in the Farringdon area back in 2004. A specialist geotechincal consultant did a sophisticated finite element computer analysis to see the effect of removing all the ballast between the foundations of the tunnel and predicted a 50mm movement. People were so worried that on the day specialist equipment propping equipment and plant was brought in as a precaution. The actual movement measured was less than 5mm.
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