Hi all:
Learning to survey using modern equipment; last time I did any was way old school: plane table and alidade (don't laugh...for real). I'm doing this for fun, not employment (thankfully). I started with a Topcon AG2 optical theodolite, to learn turning angles, and traversing...my wife owns 25 acres across a wooded hillside that is challenging enough so far to learn on.
But I've learned quickly enough that a steel tape is a pain in the .... going up steep wooded hillsides....so...
I'm looking at buying a used Total Station. The two I've narrowed the search down to given my budget (under $1k) are the GTS 300 series; either a GTS 302 or 303, or, a slightly newer (by a few years), GTS 203. The 203 is a 10" instrument but I've learned enough that operator experience is way more important than instrument precision.
I've read nothing but good things about the older 300 series from surveyors...that they're robust workhorses. Not so much about the 200 series instruments.
So, I seek advice. Any pros or cons of either?
Thanks in advance
RFC-
We all have our own 'hobbies'.
You would be so far ahead to contact a local professional licensed cadastral surveyor and explain that you wish to have your wife's lands surveyed.
What you are doing is analogous to 'doing your own dentistry', except that your wife's boundary is someone else's too and if you wish to start a contretemps, you are headed that way.
The surveyor may allow you to look at her/his field equipment at an hourly rate too.
Derek
I won't flame you for the unlicensed surveying..... The 300 series instruments were truly workhorses. I still have a 301 that is a 1" gun. My first data collector compatible instrument was a GTS 304. A friend of mine still uses his 22 year old GTS303 every day. I don't think they are water resistant though. That's the only con I can think of. Good luck.
> RFC-
> You would be so far ahead to contact a local professional licensed cadastral surveyor and explain that you wish to have your wife's lands surveyed.
Far ahead of what? You may have missed the part that I'm doing this to learn. The property HAS been surveyed, in the 80's, and was largely referencing a survey done in the 60's. I'm simply retracing it, finding the corners, etc.
>
> What you are doing is analogous to 'doing your own dentistry', except that your wife's boundary is someone else's too and if you wish to start a contretemps, you are headed that way.
A "survey" isn't a survey unless it's done by a licensed surveyor AND filed in the local town clerks office. I know that. Interestingly enough, though, I've already found that a driveway that is supposed to be within a 50'ROW is completely outside the ROW for some distance; that the house on the adjacent property put their driveway on my wife's property for some 150'.
If any of these were of concern, I would of course call a pro. They're not. I'm more interested in mapping the property; developing a super detailed topographic map of the property etc., and learning a bit of what is a challenging and fascinating trade.
Thanks for the advice though.
> Derek
About the unlicensed surveying thing....
If you were doing that in my 'hood, I'd ask you to bring your notes to my office, and we'd crunch them together. And, then I'd recommend whatever additional ties, loop closures, etc. Then go again. My fees would be that you have to buy me lunch, for a while, at some local deli, while we discuss the project. The sheer labor involved in doing this thing right, (your labor) would probably turn this into a labor of love pretty fast. You would become either my next field hand, (if you did a good job), or you would discover that surveying is not for you. Either way, unless you tried to tell me how to survey, we would become friends!
I'd give you a worksheet, and search locations. Before it was done, you'd either be in the club, out of the club.
We'd have doubled angles, and ft meters in your book.
Modern Surveying.
It's work.
N
About the unlicensed surveying thing....
I've actually thought about that, believe it or not...quitting my "day job", and going to work for a local. The problem is that most of them around here are one or two man shops (used to be 3 or 4 man shops), but with the advent of robotic total stations, they've all cut back. They're not exactly looking for more overhead.
Most of the work now seems to be either at the 'puter, crunching and drawing, or at the Town Clerks office doing research...the time in the field is minimal. Of course, most surveyors around here do property work, not construction, which is way different.
Now, my wife rents her log home on 25 acres in beautiful vermont. Perhaps I can entice a pro to spend a few days taking a "working" holiday in a fabulous home at a reduced rate. He'd have to bring his state of the art robotic total station with all the fixin's of course. 😉
A 5" 200 Series Is Absolutely What You Want
I had surveyed with a 301 for years, but big and heavy. I even did some work with a 3B & a 3C, straight 5" reading. But for day in and day out a 215 or 225 is what you want.
As an exercise check and see how precise you can be with an optical gun and a stadia. Did quite a bit of topo with them back in my AutoCAD 10 days. I have a Philadelphia Rod setup with three targets. 1,000' shots, no problem.
Paul in PA
A 5" 200 Series Is Absolutely What You Want
Thanks for the input. I have an inside track to one of two machines: a GTS 203, and a CTS 2B. The CTS seems to be a "Construction" variant, but I don't know how precise it is or what other differences there are(still looking). If you had to choose between those, which would it be? If I understand you correctly, I take your comment to mean "go with 5" or better", i.e., not 10".
So far the short traverses (less than 1000') have closed out of the gate at around 1:5000, which is as far as I can tell OK for a rural trek. That's with the AG2 (a 20" unit), but not stadia...I used a tape.
It's hard to get detail specs on some of these older units. Any links (besides the Topcon museum, which doesn't have a lot of detail) is appreciate.
A 5" 200 Series Is Absolutely What You Want
1:5000 closure is kinda sloppy. That means 1' error, in 5000 ft. My typical traverses with an old 1923 Leitz Transit, with 20" verniers, was more in the 1:15,000 or better. This was with a 200' tape, or a 300' tape, and slope chaining, or using an abney level. I'd say my average was around 1:20000.
To do that, you have to peg the inst. And, run it right. And, know how to tension the tape, but it is not too hard, once you get the hang of it. Now a days, with RTK gps, or Post processed L-1 GPS I hit our old work typically in the 0.15' per 1/4 mile. Some of that error is in the GPS!
Surveying, It's not for everybody.
N
A 5" 200 Series Is Absolutely What You Want
Now I have a good idea of what to shoot for! Got a ways to go though. Of course it's "kinda sloppy" so far. Your kind of expertise doesn't happen overnight. Plus, my "rod man" at the time was my son, who in addition to having a disability has ADD...He's holding the rod next to the well casing (crooked); I turn around to do some calculations and look up, and he's no where in site, having propped the rod on the casing (at about a 20 degree angle). He also couldn't hold the tape well enough to keep from being pulled over, so I'm sure some of the closure error could be due to that.
Today it got even worse...1000' up a steep wooded hill; Why is it that there are always massive trees on the line you're trying to traverse? Is that some unwritten rule? Had to do two offset shots in a row; nearly complete wash out. By the time I got back on the line, on paper it showed I was at least a foot off it. The neighbor's ground mounted transformer not too far away is visible from space on google earth, so I'll know for sure when I measure to it.
Having fun though.
Still looking for an answer on the 5" or better question, if you might.
A 5" 200 Series Is Absolutely What You Want
CTS is a "construction grade" instrument... optics aren't as good, it's probably 10" (or even 20") and probably only has a single axis compensator. Good enough for dirt work but I wouldn't want to survey with it; go with the GTS.
A 5" 200 Series Is Absolutely What You Want
The CTS-2B does not have a compensator. The GTS-203 has a vertical compensator. The EDM in the GTS-203 may be a little stronger but not much. Either would probably be sufficient for the task.
If your main point is to gain experience by retracing your boundary, I think any of the three you mention would be fine for such an endeavor. As you say, in the application you are interested in, the accuracy of the total station you are using will likely be the last thing that comes to play in the relative accuracy of your work.
A 5" 200 Series Is Absolutely What You Want
Exactly the kind of feedback I was looking for. Still a little confused on what they actually mean by "accuracy". Instruments that call out 10" accuracy, seem to have minimum readout increments of half that, which may mean you could be off 5" one way or another for a total of 10"?
In any case, even at 10", on paper at least, is .05' on a 1000' traverse, which I'd be thrilled with, given my performance so far with my optical unit (which claims 20" accuracy). I'm getting no where close to the capability of the instrument, which leaves me as the culprit, not the instrument, I'm sure of that.
If I had to guess though, I'd say my lack of skill with the tape is probably a bigger factor than with turning angles. The EDM capabilities would therefore probably contribute more to the overall challenge of closing ratios of 15,000 or better.
I'm good with not spending time looking for anything better than 10" for now. I've got time to shop, and a lot of work to do.
A 5" 200 Series Is Absolutely What You Want
I would probably opt for the GTS-203 between the two if there is not much difference in the price. One reason for that is that the GTS-203 has a three-line display that will show horizontal angle and zenith/slope distance or horizontal distance/vertical difference all on one screen.
The same information is available on the CTS instrument but only by toggling between screen displays.
A 5" 200 Series Is Absolutely What You Want
Buy the best the budget will allow. I am tinkering with measurements just for my own interest and education, and I bought a GTS-2B several years ago. There are probably much better used instruments now in the price range that I paid then. I would put EDM range and accuracy up there with angular accuracy in my priorities.
If you don't have much background, buy a book on basic surveying. My favorites are a 1960's Davis, Foote, and Kelly to see how it used to be done, and a not-quite latest Wolf and Ghilani for more up-to-date info. The older book actually teaches you more about getting the best accuracy from an instrument.
One technique that took me quite a while to appreciate is reading angles Direct and Reverse (or Face 1 and Face 2). This cancels out some instrument errors. If you have significant vertical change in your traverse, the D&R is especially important.
The standard for rating angular accuracy is confusing and I always forget it. I think it says you have to average two D&R sets to expect the rms error to match the instrument spec. If I'm wrong, someone please correct me.
