Passive Stations Update

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Passive Stations Update

Postby agentmancuso » Thu Jan 09, 2020 7:54 pm

Following an FOI enquiry about Passive Stations to Ordnance Survey by James Southgate, a significant number of edits have been made to the T:UK database.

19 existing OSGB36 triangulation stations have been flagged as Passive Stations, and 24 further Passive Stations have been added. A handful of further Passives remain to be identified.

These stations appear to have been deleted from the Passive Station Database at an early stage; 3 are actually labelled as GPS stations in the OS Benchmark database, indicating they were among the very first Passives.

Unfortunately no sketches or photos are available, but details for 13 of the new stations can be found on OSBM, which might help a bit.

As far as I can remember, this is the biggest increase to the total of T:UK entries since bulk import of the OSGB36 archive tripled the size of the database a number of years ago.

(Crossposted to FB page)
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Re: Passive Stations Update

Postby ted » Sun Jan 12, 2020 1:03 pm

Thanks Bernie. By chance, I noticed these updated and was wondering where the information
came from :)

One that interests me is tp25831 Riber GPS http://trigpointing.uk/trig/25831 at SK 31096 58850
which is very nearly the same location as TP0607 - Matlock FBM Aux 1 http://trigpointing.uk/trig/607
at SK 31097 58849 (Passive Station H2SK3058).

Presumably the bolt was replaced by a Berntsen and renamed
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Re: Passive Stations Update

Postby agentmancuso » Sun Jan 12, 2020 1:49 pm

Well spotted Ted. I guess that explains the '2' in the Matlock FBM Aux prefix. I'll email you the list of new stations.
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Re: Passive Stations Update

Postby ted » Mon Jan 13, 2020 3:57 pm

I guess that explains the '2' in the Matlock FBM Aux prefix.


Aargh! My mistake. The Passive Station record for Matlock FBM Aux 1 is:
https://www.ordnancesurvey.co.uk/gps/legacy-control-information/H1SK3158 (not H2) :(

After posting yesterday's reply, it eventually dawned on me that I'd studied the passive stations
in this area some years ago. It used to be possible to query the OS database with a crafted URL to look
for stations that might exist but weren't listed in a search query. In that way I identified Riber as C1SK3158
downloaded 9 Feb 2011 which contains the following (nb the reference to SK315585 doesn't seem consistent):

---

Riber C1SK3158


Type of mark: Surface Block Last visited by OS: 08/02/1995
Flush Bracket: Not available On Landranger sheet: 119
Grid reference: SK315585 On Explorer sheet: 24
Access to mark: 2WD Vehicle Permission required: No
Keys required: No
_________________________________________________________________

Coordinates of this station
Date of observation: No date available Coordinates last checked:
08/02/1995
Planned next check: 08/02/2000

ETRS89 Cartesian ETRS89 Geodetic
X: 3834263.186 m Latitude: 53� 7' 33.3894'' N
Y: -102864.322 m Longitude: 1� 32' 12.2758'' W
Z: 5079186.984 m Ellipsoid height: 276.171 m

National Grid (converted by OSTN02/OSGM02)
Eastings: 431096.746 m
Northings: 358850.684 m
Height: 226.302 m (Orthometric height above MSL, Newlyn Datum)
_________________________________________________________________

Land Owner
Land Owner: Not available
Owner's Address: Not available
Telephone: Not available
Email: Not available
Owner's Agent: Not available
Agent's Address: Not available
Telephone: Not available
Email: Not available

NB: If 'permission required' is Yes at top of this form, the land
owner or agent's permission must be obtained before accessing the
mark. If you fail to gain permission, contact us.
_________________________________________________________________

Location Sketch and Photograph

There is no photograph available for this station.

There is no location sketch available for this station.
_________________________________________________________________
[end of passive station record]

From a comparison of grid refs:

Riber
Eastings: 431096.746 m
Northings: 358850.684 m
Height: 226.302 m

Matlock FBM Aux 1
Eastings: 431096.749
Northings: 358849.283
Height 226.318

=> So Riber (if it still exists) should therefore be 0.3 cm West, 1.401 metres North of the Berntsen
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Re: Passive Stations Update

Postby agentmancuso » Mon Jan 13, 2020 6:12 pm

Thanks for that Ted. Glad to see that your coords for Riber match those from the FOI!

It's not your mistake with Matlock Aux 1 though; T:UK lists it as H2SK3058, so the confusion must originate in the PSD itself, unsurprisingly.
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Re: Passive Stations Update

Postby ted » Thu Jan 16, 2020 5:09 pm

Thanks Bernie,

I've also noted https://www.bench-marks.org.uk/bm114863
so either the Riber passive was also a benchmark or things are getting very confusing :shock:

Hoping to make a site visit soon, weather permitting.
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Re: Passive Stations Update

Postby agentmancuso » Thu Jan 16, 2020 6:12 pm

Yes, quite a few of the new passives (and some of the original non-OSGB36 passives that were on T:UK from the very beginning) are also BMs.

Will try for Ballantrae on Saturday myself.
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Re: Passive Stations Update

Postby ted » Mon Jan 20, 2020 3:22 pm

No luck with Riber :(

Next visitor please take a small chisel or heavy-duty screwdriver and find out whats under that
damned lid!
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Re: Passive Stations Update

Postby agentmancuso » Tue Jan 21, 2020 9:38 pm

None with Ballantrae either. Pretty sure it's been gone for ages, replaced by Laggan Holm along the road.
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Re: Passive Stations Update

Postby ted » Thu Feb 06, 2020 5:00 pm

No luck with Riber :(

Next visitor please take a small chisel or heavy-duty screwdriver and find out whats under that
damned lid!


Thanks to RHW for following-up and identifying that the lid covers a water meter.
Given that this is pretty much exactly at the grid reference given by the OS, the
conclusion is that the Riber trig station has been destroyed.

As regards the mystery inscription, Rob established that, in full, it was 'STW BB'.
Severn Trent Water is obvious enough. As for 'BB', a web search indicates that
STWBB is 'Severn Trent Water Board Birmingham'. Not as I had imagined,
'Buried Block', 'Before Berntsen' or even '****** Brexit' :)

Manhole covers even have their own web site:
https://manhole.co.il/coverDetails.asp?c=3786
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