A Triangulation Station & an Intersection Station?

[+EdrickV]

Can a mark be both a triangulation station and an intersection station? I haven't seen any datasheets for intersection stations that are discs, they're normally things like building spires, water tanks, and other such stuff. Not survey discs set flush with the ground. But I've found a datasheet for a triangulation station that also says it's an intersection station, so this is a bit curious. (I was experimenting with GSAK filters to find Intersection Stations that NGS>GPX didn't catch.)

 

The datasheet:

http://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=CN3064

No listed recoveries (on either site) since it was placed, so I don't know if it's even around anymore, but I'm curious about that datasheet.

[tosborn]

That does seem unusual. Maybe it wasn't occupied (as in setting up a theodolite on the station from which to sight other objects) since there is no box score.

Edited May 12, 2012 by tosborn

[Bill93]

Yes, if they set a disk but never took measurements with an instrument over it, but only used a signal (sighting target, usually a lamp for nighttime observation) then it would be an intersection station and not a triangulation station regardless of what the disk said. That would be unusual.

 

But I thought that an intersection station could be no better than 3rd order and this data sheet says 2nd.

[2oldfarts (the rockhounders)]

It sounds like there was a blending of the descriptions for 2 different marks.

 

I don't ever recall seeing an intersection station that had a surface mark, an underground mark and 2 reference marks as well. We have seen the reference to height of light in descriptions for triangulation stations, but they were clearly disks where the light was above the disk that was being used at that time.

 

John

[68-eldo]

There are a number of stations around here that can be used as both an intersection station and a triangulation station. A couple of examples are TU1455 Ewa Church and TU0625 Gilbert. Gilbert is missing the signal on top but you can see in the pictures on GC that there is a disc under the bench that holds the marker. And you can see Gilbert occupied by a GPS receiver. Gilbert also had two reference marks but I could only find RM2. I think RM2 is now gone.

 

Ewa Church shows the flag that was found on all the stations with a permanent “A type territorial red and white survey signal” over the mark.

 

I don’t see that they are designated as both.

 

HTH