Trig points - a general discussion

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Zalgariath
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Re: Trig points - a general discussion

Post by Zalgariath » 06 March 12 9:22 am

I started to photo UK Trigs, but as there is already a dedicated website with the same TP numbers as in Oz, I let them slide as GCA finds. Hate dual listing :P

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pjmpjm
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Dangerous Trigs

Post by pjmpjm » 06 March 12 6:54 pm

rogerw3 wrote: Except it may not be a good idea to take photos of Trigs in China when you get there! :-"
Except that he might then be able to log the GCA Locationless 'Long Arm of the Law' -- like I did!

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JustinCBR
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Re: Trig points - a general discussion

Post by JustinCBR » 23 June 12 7:42 pm

After reading this thread, I am left confused and unsure how I can verify whether a possible trig that I've found near the Harbor Bridge in The Rocks (on Argyle St). I read somewhere that a trig could be a bolt marked with a triangle to signify that it is a trig. Is it possible that it is an old trig that was removed when the bridge was constructed but still has a marker? Perhaps some of you trig experts can tell me what you think? I found it while on my way to look for the Observatory Hill multi - still haven't found that cache, tho I do have the coordinates.

Image - https://www.dropbox.com/s/vpqiiylfn8ncd ... .04.10.jpg (still trying to figure out how to get the image to post.)

JustinCBR

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mtbikeroz
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Re: Trig points - a general discussion

Post by mtbikeroz » 23 June 12 7:58 pm

That photo looks like a bolt in the ground, and nothing more.
However, if some old maps refer to that point as a "Trig", it's a Trig!
If it's on maps as a survey mark, not a trig.
If a plate next to it stating "so & so trig", then it's a trig, but I don't see such a plate there.
That's generally how we in Canberra have gone about it. (more or less :( )

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McPhan
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Re: Trig points - a general discussion

Post by McPhan » 24 June 12 9:26 am

Dan Brown could be interested in it...

Kerry
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Re: Trig points - a general discussion

Post by Kerry » 24 June 12 9:54 am

That appears more likely a cadastral reference mark as even opposed to a permanent survey mark? Typically cadastral boundaries are referenced to buried marks (pins), trees etc but in the concrete and asphalt jungle the only reference options are typically things like bolts/ramsets/Gin's etc in kerbs, footpaths, concrete/bitumen.

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Yurt
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Re: Trig points - a general discussion

Post by Yurt » 24 June 12 10:17 am

If it's in The Observer's Great Big Book of Trigs then it's a trig apparently. :mrgreen:

It's just a benchmark from what I can tell. The most minimalist trigs are PM hatches with the name of the trig on a plate inside. Being trigs they would also have to be on some sort of high point.

Rogerw3 has a reference list of sorts for NSW so can confirm or deny usually.

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pjmpjm
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What is a Trig?

Post by pjmpjm » 24 June 12 3:01 pm

JustinCBR wrote: After reading this thread, I am left confused and unsure how I can verify whether a possible trig that I've found near the Harbor Bridge in The Rocks (on Argyle St). I read somewhere that a trig could be a bolt marked with a triangle to signify that it is a trig. Is it possible that it is an old trig that was removed when the bridge was constructed but still has a marker? Perhaps some of you trig experts can tell me what you think? I found it while on my way to look for the Observatory Hill multi -- still haven't found that cache, tho I do have the coordinates. JustinCBR
This is an old discussion thread here at the GCA Forum. A Trig or TS is registered with the old NSW Department of Lands. Trigs can take many forms, including the tops of church steeples, radio transmitter masts, bolts in the ground, etc. What they all have in common is an officially registered TS number.

If you have questions, please PM rogerw3, who is one of our GCA experts on trigs and survey markers of all kinds. For the past couple of years he's been compiling a comprehensive database of NSW trigs and a great many of the published trigs on GCA derive from his research.

Many marks such as you describe (can't see the photo) are various kinds of survey markers -- another topic of discussion altogether . . .

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pjmpjm
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Mystery Marker Near Sydney Harbour Bridge

Post by pjmpjm » 24 June 12 3:06 pm

JustinCBR wrote: Perhaps some of you trig experts can tell me what you think?
Just managed to view the photo you uploaded. It looks like a benchmark to me. It's not a typical NSW State Survey Marker, for sure. Some replaced trigs have taken this particular form, however, and the only way to be sure is to consult the NSW Department of Lands database.

Since rogerw3 has carefully searched the Sydney CBD area over the past year, and indentified all exisiting trigs, I doubt that he's missed this one. However, I'll ask him for his feedback.

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GammaPiSigma
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Re: Trig points - a general discussion

Post by GammaPiSigma » 05 September 12 1:27 pm

Does anyone know what these are:
Image

I have found three on Queen St in Campbelltown and one in the car park of Campbelltown Hospital.

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Yurt
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Re: Trig points - a general discussion

Post by Yurt » 05 September 12 11:04 pm

Dozens of them in the Sydney Olympic Park area often only metres apart.

I dunno. I thought they were some sort of RTA marker. There are such RTA/DMR survey marks along the major roads but I don't know what these are. The hatch is usually screwed down so you can't check inside.

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Big Matt and Shell
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Re: Trig points - a general discussion

Post by Big Matt and Shell » 05 September 12 11:27 pm

This website lists them as flushing point covers.

Not too sure from there... Perhaps something to do with sub soil drainage?

EDIT: This doc probably backs that up.

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RTA SS Markers

Post by pjmpjm » 06 September 12 2:36 am

GammaPiSigma wrote:Does anyone know what these are . . . I have found three on Queen St in Campbelltown and one in the car park of Campbelltown Hospital.
rogerw3 explained them to me, but the details have slipped my mind.

I'll ask him to post here.

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rogerw3
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Re: Trig points - a general discussion

Post by rogerw3 » 06 September 12 9:59 am

The SS (State Survey) marker you have here is possibly a numbered marker since it is not screwed down and is of an older type, I have come across this type before and they are usually registered as a marker with the lands Dept (no idea what they are called these days since they are now part of the Finance Dpt).
The current survey markers from the RTA (now RMS) are usually not registered with the lands Dpt and the lid screwed down so you cannot open them. They are used by the RTA during road construction or sometime where a road is/was planned.
If you have the coords I can try to find out if they are a numbered Survey Marker for you.

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gmj3191
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Re: Trig points - a general discussion

Post by gmj3191 » 06 September 12 12:43 pm

The cigarette butt is a nice touch.

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