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Post by orienteer on Jul 7, 2022 9:30:26 GMT
New structure observed, wondering what it is. On the south side of the Uxbridge branch, immediately to the East of the Central Line overbridge between Ruislip and Ickenham, a white pyramid shape about 5ft high, with what looks like an air sampler on top, and a large solar power array next to it, presumably to power it.
Could be a pollution monitor? Train is going too fast at that point to be able to photograph it.
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Post by marri260 on Jul 7, 2022 11:32:28 GMT
I believe, some kind of laser monitoring system for ground movement for the HS2 tunnels passing under the Uxbridge branch there, just on the Ruislip side of the Central line / Chiltern overbridge. There are laser monitoring tags (no idea on correct term) attached to both running rails on both roads starting under the bridge and continuing for a short distance towards Ruislip. All appeared perhaps 6-8 weeks ago now at a guess.
One assumes the HS2 tunnels won't be particularly deep at this spot, with the West Ruislip portal a short distance away.
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Post by goldenarrow on Jul 8, 2022 11:58:24 GMT
There are indeed a pair of Automated Total Stations (ATS) installed lineside to monitor ground movements in relation to the construction of the Northolt tunnels for High Speed 2. Launch of the tunnel boring machines West Ruislip portal towards Northolt is due to start in August.
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Post by orienteer on Jul 27, 2022 13:31:41 GMT
Belated thanks for the info.
I recall seeing an aerial photo of the course of Crossrail across central London with ground movement highlighted in red; only millimetres but detectable.
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