RTK for ALTA surveys

For random location such as edge of pavement and utilities, why not? The new 2011 proposed regulations now speak to error ellipse etc...so I think that you could use GPS for boundary assuming that your control is good and your errors are within tolerances...

I'm mainly talking just the boundary corners, not the topo.

Sure,

Why not?

Might have to mix in a couple of conventional shots, but proper methods and common sense rules.

I have no problem at all.

I get confident shots and closures every day with proper use.

Occupy your boundary at least twice during the time spent on the job.

RTK on a ALTA will make you some profit if you use it right.

Right now the satellites are good all day long, so take advantage and prosper.

Randy

I see them done all the time by one of the large regional firms in this area.

Horizontally they seem to be pretty good, but we have a CORS station in town.

Vertically, I've seen them vary by up to a tenth.

Boundary and all the topo. If there's enough redundancy, I guess it would be OK.

> Can RTK be used for ALTA surveys?

Sure. Using LS you can get error ellipses for single RTK shots. Of note - you get no such ellipse with single total station shots. Anyway, the specs don't require that you actually produce some adjustment report, only that the positions you report would be within the position accuracy when re-surveyed next time.

" Computation of Relative Positional Accuracy

Relative Positional Accuracy may be tested by:
(1) comparing the relative location of points in a survey as measured by an independent survey of higher accuracy or
(2) the results of a minimally constrained, correctly weighted least square adjustment of the survey. "

I just finished doing an ALTA in Houston with RTK (Trimble R6.) We had no problems with it as we just tied mostly paving. The only problems we had were getting up close to the building (a 3-story +/- 45' tall bldg) at some times of the day, but could get close later in the afternoon depending on where the satellites were. The building corners were a bit of the problem too, so we ended up tying those conventionally. We did all the boundary with RTK though , and had no problems!

>Of note - you get no such ellipse with single total station shots.

Error ellipses can be generated for any total station shot. They tend to get large fast if you're not shooting from network points, but they're available none the less.

Ellipses for sideshots taken from network stations are pretty reliable, as long as your methods are good. The nice thing about total station work is that shots taken from a given setup tend to be very tightly correlated, something that can't be said about adjacent RTK shots.

RTK is good enough for any kind of surveying if you don't care if the measurements are within many feet.