Geodetic Control Diagrams and Triangulation Diagrams for TX

Nobody? 🙁

I have a few in Nevada, Utah, Wyoming, but never gave a crap about Texacus.

😉
Loyal

Howdy,

I assume you are asking because you were unable to get them from NGS via either the Information Center or the Texas State Advisor?

Cheers,

DMM

Well Mike, I didn't actually try either only because I am assuming these aren't really used by anyone anymore and are no longer produced or maintained or available?

Jesse

> Howdy,
>
> I assume you are asking because you were unable to get them from NGS via either the Information Center or the Texas State Advisor?
>
> Cheers,
>
> DMM

😛

Still think they are the most likely source. Mr Middleton, senior NGS advisor to Texas, might have them or know where to obtain copies. For contact information see: http://www.ngs.noaa.gov/ADVISORS/AllStates.shtml#TX

I have quite a few, but none in Texas. Most of the NE and also MN-IA area. I really wish someone would make these into DRG's or at least PDF's so that they will be preserved. There are many who think all of this info is worthless now that we have GPS and CORS and HARN, but the fact is there are many thousands of older surveys out there that were based on these networks, and it is very useful to know how the coordinates of the control were determined. I hope this data isn't going to just disappear.

For those who don't know, these were crucial in the early days of GPS. Before CORS, before HARN, there was only triangulation, trilateration, and traverse stations for control. This was also before the internet. So, the only way to know what control was out there was to get the control diagram for that area, which were on 1° X 2° 1:250,000 map sheets. I would always look for stations that had good geometry, preferably a corner of a quadrilateral or, even better, a station in the Transcontinental Traverse (TCT). Here is an image of an area near me where I did extensive work in the early days.

this particular area has first order stations (larger bold triangles), second order stations (smaller triangles), and USGS triangulation (in red). The bold lines are measured distances, and the TCT goes right through this area. The highlighted stations are ones that I used. Also shown are level lines (solid=1st order, dashed=2nd order, and red dashed=USGS). There was also a lot of non-TCT lines measured here, in 1975 they did a triangulation/trilateration densification.

It was important back then to pick the best stations possible, and to know how they were connected. For example, from first order station BEAR, lower center, to first order station HALL, upper left, was quite a bit further through the network than direct, so it might be expected to have a larger misclosure than if they were directly observed between.