How do you do that?

Ummmm

There are a number of ways to get a Lat/Lon with a Total Station, including Astro observations and computations.

Be sure and post your results when you check this baby out, I'm really curious to see how close he was.

😎
Loyal

I'm betting they had GPS coordinates somewhere that they traversed in from. I can see why they didn't get GPS on this point.
NJ0353'SET VERTICALLY IN THE SOUTH FACE OF A 60-FOOT HIGH ROCK CUT
and Google Earth shows a LOT of trees just across the road. I don't see any place close that I'd want to set a GPS, nor any way to sight this except from the highway.

.

They must mean that they observed some ground control and made a secondary observation to the mark from those points. Those coordinates take you right to it on Google Earth. You can see the circle painted on the rock wall in street view.

Bill93, post: 452681, member: 87 wrote: I stumbled on this recovery report, and scratched my head a bit. Probably a tech who didn't distinguish between GPS and TS. If it really was TS then I want to know what other stations they based it on.

NJ0353 STATION RECOVERY (2016)
NJ0353
NJ0353'RECOVERY NOTE BY WHKS & CO 2016 (JL)
NJ0353'USED TOTAL STATION SURVEY INSTRUMENT TO DETERMINE LATITUDE 42 33
NJ0353'33.48523 N, LONGITUDE 90 44 59.75408 W

These days 99% of the points collected by my TS have a Lat, Long attached to them available at the click of a button.

Back in 1981 in school we broke up in crews and ran a traverse between triangulation stations. As I recall, we got the lat and long on each station, converted them to State Plane Coordinates (must have been NAD'27 back then) backsighted a reference mark and ran the traverse to the other station. We reduced each of our measurements to State Plane. and ran the coordinates in state plane to check in to the final point. I remember the crew I was on did real good and another classmate was griping, saying "It's kind of strange that that is the only crew that closed tight, and everyone else was a foot off." Who knows if we made compensation errors, or if all the other guys were doing something wrong.

Of course no total stations back then, or even infrared edm's. I remember we had an old laser edm, and I don't remember if we used that on this exercise. Maybe we shot between the triangulation stations...not sure. Memory on some of the details might be a bit faded.

Tom Adams, post: 452702, member: 7285 wrote: Back in 1981 in school we broke up in crews and ran a traverse between triangulation stations. As I recall, we got the lat and long on each station, converted them to State Plane Coordinates (must have been NAD'27 back then) backsighted a reference mark and ran the traverse to the other station. We reduced each of our measurements to State Plane. and ran the coordinates in state plane to check in to the final point. I remember the crew I was on did real good and another classmate was griping, saying "It's kind of strange that that is the only crew that closed tight, and everyone else was a foot off." Who knows if we made compensation errors, or if all the other guys were doing something wrong.

Of course no total stations back then, or even infrared edm's. I remember we had an old laser edm, and I don't remember if we used that on this exercise. Maybe we shot between the triangulation stations...not sure. Memory on some of the details might be a bit faded.

Most everything back in the day was state plane, I started to get off state plane when I got GPS, but before that, most of my large surveys were based on NAD27 then NAD83 monuments.

It was a real time saver to have control spaced around the area to use, even in town if a subdivision was done it was state plane. Small lot surveys or topos were just 10000, 10000.

I had a massive survey for a number of AML sites starting in the early 80's. The surveyor in charge was against using any state plane data. He wanted 10000, 10000. I informed him that we were going 25 miles southeast and 10000, 10000 wouldn't work very well, we compromised on 100,000, 100,000. Barely had enough coordinates to make that work either.

I did tie all the state plane monuments I could easily find, just didn't tell him. We wasted so much time spinning around the 100,000, 100,000 system. But he was in charge.

That's a lonely monument. The data sheet coordinates were scaled from a map and published to the nearest second. Compared to the recovery coordinates, the scaling work was pretty good.

https://www.ngs.noaa.gov/NGSDataExplorer/

MightyMoe, post: 452711, member: 700 wrote: going 25 miles southeast and 10000, 10000 wouldn't work very well, we compromised on 100,000, 100,000.

That's an awfully large area to pretend the earth is flat. If you have a "square" area with that diagonal near 45^ latitude, I made a rough computation that traversing the perimeter would miss closing by a whopping 400 ft, or 1 : 930

Not sure what AML was in the 1980's, so maybe that was sufficient accuracy.

Bill93, post: 452726, member: 87 wrote: That's an awfully large area to pretend the earth is flat. If you have a "square" area with that diagonal near 45^ latitude, I made a rough computation that traversing the perimeter would miss closing by a whopping 400 ft, or 1 : 930

Not sure what AML was in the 1980's, so maybe that was sufficient accuracy.

Could you have a series of closed figures that all work within themselves to a higher precision, with common lines between them? Yes, it wouldn't account for curvature, but it may well be good enough for the task @ hand. (that's not a rhetorical question. It seems adequate to me, depending on the product needed)

Sure, local accuracies could be much better, and if you did everything by branching off a more central traverse you wouldn't notice the problem.

I tried another computation and got a different answer, so I had some problem in my calc and not sure which is better, but still that order of magnitude.

Bill93, post: 452729, member: 87 wrote: got a different answer

Ok. The first computation was going to the SE corner by two different routes E,S vs S, E.
If you truly traverse E,S,W,N you miss by 585 ft or 1:638
The difference comes from the fact that the back azimuth is not fwd azimuth+180.

The real-world answer would be something else because you would use much less than 17.6 mile sights. Still, it shows that distance stretches the limits of plane geometry on a curved earth.

Bill93, post: 452726, member: 87 wrote: That's an awfully large area to pretend the earth is flat. If you have a "square" area with that diagonal near 45^ latitude, I made a rough computation that traversing the perimeter would miss closing by a whopping 400 ft, or 1 : 930

Not sure what AML was in the 1980's, so maybe that was sufficient accuracy.

AML is Abandoned Mine Lands, reclaiming old mines. The area was larger than 25 miles, 25 miles SE was just from the POB. The first task was photo control and from there void areas which was mostly the 200 reservoirs that were created by the mining activity, then staking for construction and finally topos for volumes.

Basically we laid out a grid, in reality state plane is a grid, pushed down to sea level in those days.

Anyway, it worked out fine, northings got small at the SE end and eastings got small at the NW end, traverses closed very well and what was really interesting was how good the mapping was after we would adjust to it for each site. This was the first job I ever did breaklines on, and the engineers were really happy how the volumes matched. Way better than the old XS days.

Bill93, post: 452681, member: 87 wrote: I stumbled on this recovery report, and scratched my head a bit. Probably a tech who didn't distinguish between GPS and TS. If it really was TS then I want to know what other stations they based it on.

NJ0353 STATION RECOVERY (2016)
NJ0353
NJ0353'RECOVERY NOTE BY WHKS & CO 2016 (JL)
NJ0353'USED TOTAL STATION SURVEY INSTRUMENT TO DETERMINE LATITUDE 42 33
NJ0353'33.48523 N, LONGITUDE 90 44 59.75408 W

The firm is working on a DOT project. Because it is a geographic coordinate system all project coordinates have a Lat and Long associated with each.
Btw, JL is licensed.