So, I get a request to put together two right of way projects. They don't quite meet near a bridge that got reconstructed for the first of the two projects. The second project is north of the bridge but didn't quite get to it so they aren't connected with common points. Both are GPS. However, the older one is Metric, I'm thinking no big deal. Then I look deeper into it and discover its not only Metric, its NAD27 Metric.?ÿ
1997 era. Had GPS then, but not static GPS so this is a calibrated project using NAD27 Metric data.
I don't even have Trimmap anymore. Not that it would have done much good. DOT would hand out the control points and we would occupy them and use their positions as a given. Then we were taught to occupy other control and calibrate after locating them.?ÿ
There is no way to merge these two jobs without boots on the ground.?ÿ
Trying to explain why didn't go over very well.?ÿ
It's too bad the original GPS observations didn't get archived. I'm just finishing up a job that involves DOT coordinates with the majority of my work built off DOT's project centerline coordinates, all paved over in the travel lane of the busiest section of highway in the state, very, very few reference monuments. Something got goobered up in getting onto this stuff and thankfully I was able to post process the raw GPS observations to track down where things went sideways. Without that raw data, I'd been pooched trying to figure it out without reinventing the wheel.
They are archived, problem is they are meaningless.
We didn't have static, the control would have been in NAD27, not tied to any CORS, possibly instrument control from some of the nearby 27 monuments. Almost impossible to re-create. Easier to simply go locate some control, some ROW monuments and rotate/translate the figure in.
I do have in the back room disks to load up Trimmap. Might have to do a virtual desktop to use it and I'm not going there after the last few months of cyber attacks.
Please explain; "1997 era. Had GPS then, but not static GPS so this is a calibrated project using NAD27 Metric data."
In the beginning the only GPS there was, was static. No sweat, find as many control points as you can nearest the new project area and static GPS. You do not have to hold more than one of the former control point coordinates or maybe even none. All you really care about is relative distances being within tolerances. Your job is to connect existing construction, not match ancient coordinates.
Paul in PA
Our units then only were RTK, no static. Yes to merge the two projects it will require going to the field and surveying as I stated above. There will be no need to do any static. The R-10s we are using today will have no problem getting super tight locations using RTK. The issue is they don't want to pay for it, and of course I'm not going to do it for free.
Does TBC have import routines for the older DCs (I have not used Trimble in over a decade)??ÿ Do you still have the original DC files? Did you typically collect the QA/QC matrix data on your jobs?
If the answer to these questions is yes to all then you should be able to recreate the observations.?ÿ If I recall correctly, the covariance matrix contained the raw vector data for the observation.?ÿ From there you can merge and update your data to the current datums if you have it on any control.
P.s. Thanks for reminding my of TrimMap.?ÿ The only thing worse was TSO.
I'd like to say I still have a copy of those but they did not make the cut on the Covid purge.
I'm not sure if it's possible, I do have the disks for trimmap and could probably reload it and the files are off in an archived tree. But, it wouldn't accomplish anything really. There is no conversion between NAD27 and NAD83 that is accurate enough for me use. Possibly someone who doesn't care about being very accurate might use one of them.
It would be faster and easier to simply go reshoot the control for the NAD27 job. Then rotate the drawing file in to the new positions.
I used to create a DC file from Trimmap then import it into TSO. Then they switched to TGO and there was an interface between TSO to convert to TGO, now there is an tool that will convert TGO to TBC. However, they recently sent out a message that in September that tool will be discontinued.
The issue is they don't want to pay for it
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They would pay me for fieldwork or I would not do the job.
Next time say "We did not do static" not "They did not have static".
Paul in PA
The NAD27 to NAD83 is always nasty, and unless you happen to have some control with both then your going to have some field observations.
As for the raw data, I was referring to the field data out of the TDC1. I'm not even sure that TBC will import the old TDC1 format but if it did and the projects were larger, it might save some time in the field.
I have the hardest time keeping a straight face when clients ask me to pull a rabbit out of my hat.
Forgive me, no disrespect but I'm a surveyor, not a magician.
No Paul I said it correctly, They (being the GPS units) DID NOT HAVE STATIC.
Can't say it any clearer.
I think, if I could track down the old DC file it may be compatible with TBC, not sure, most of those old jobs were archived and transferred long ago.
Yeah, NAD27 is a resurvey situation.
It would be faster and easier to simply go reshoot the control for the NAD27 job. Then rotate the drawing file in to the new positions.?ÿ
At first blush, this may be the answer to the client pay reluctance. You should be paid either way and the reshoot/rotate solution could perhaps be sold as being cheaper. Just forget the impossibility!
@mightymoe Have never used GPS units the would not store collected data. Ten year old raw gps data has helped me tremendously over the years.
