So are you the one that did the traverse in the field ? Just asking cause it might not be Harry Potters fault. Are you really Lord Voldemort .
there is only a couple firms that do 90% pipe line work in N.C. so be carefull who you bad mouth .
Just return the trav you have a bust somewere. 6' in a couple miles is way out of being exceptable .
Larry, we are talking about GPS points about every 2 miles here and using ground distances between them and grid bearings, not SPC or other rectangular coordinate system, it could be called a polar coordinate system if coordinate is the word demanded but it is vectors only that I am suggesting, they work well for many things. SPC are useful tools but they are not always the proper tools to use and GPS receivers can provide very good vectors between points, convert the vectors to ground distances and leave the Bearings alone and you have very good control for your traverses to use.
jud
> So are you the one that did the traverse in the field ? Just asking cause it might not be Harry Potters fault. Are you really Lord Voldemort .
>
> there is only a couple firms that do 90% pipe line work in N.C. so be carefull who you bad mouth .
>
> Just return the trav you have a bust somewere. 6' in a couple miles is way out of being exceptable .
No I was not the one to turn the traverse. This is not a problem on one project, it has been ongoing from what I am told about past projects. I'm not trying to bad mouth anyone but if I hear you say to a fellow co-worker (who doesn't have a clue either) "that you don't want to ask the question on here because you are scared of people telling you that you are an idiot or a dumbass" (actual words) then that just makes you that much more of a dumbass.
It doesn't matter to me if someone sees it, it's not like I haven't made it known anyway. I unlike the real Harry Potter am trying to better the company not hurt it by being stubborn. I know what I would do and have done but I just want to get other opinions as to procedures to offer a fix and I'm not scared to ask a question.
> Your dissing of using many scale factors is not any big deal in Carlson software.
> I hope your continuing education is good enough to educate NC DOT, TX DOT, UT DOT,
> and MO DOT who use a fixed scale factor for a district or one scale factor for the
> project or multiplying the coordinate positions by the factor (in error).
I am well aware of Carlson's ability to calculate a unique combined factor for each and every point on a project. So long as the work products stay completely in house and there are clear notes on what procedures were used, there is nothing wrong with that approach.
Problems start to arise when you must create products for others outside the company. If on the hypothetical pipeline I mention above you cross say 5000 properties, and create as many maps, you will need to be very specific about what conversion factors were used. At that point things can get very tricky.
This is why I say for the situation described, the best idea is to keep everything on grid.
Larry P
What is used now is 2 hour opus sessions (1 time) for each of the control nails in a pair.
Field guys use TDS Ranger data collectors with Survey Pro, CAD is LDD 2008. Thats all the software. Civil 3D in the future.
The guys then traverse from pair to pair using only single turned angles. I would use double angles at least to make sure you don't have a bust in one single angle. The last one was 3 miles long and they turned the traverse 3 times and came up with the same angles every time within reason and are good on distance from end to end within a couple tenths but off left and right 4-6 feet hence the rotational problem
They also will get a back sight and then get any side shots and then traverse sometimes after hundreds of shots. I feel like if you are going to do that you need to re-zero and level before you traverse. I would use 3 guys and that way the time it takes to turn that critical angle is minimized and then get any side shots.
I've noticed (since RTK took over) that crews are only turning single angles between points. I just can't accept that practice. I was taught in the beginning of my career, to always turn forward and reverse, and 2-4 sets. Mean all of them. I found my elevations and horizontal closure was always within a few hundredths, along with catching bad angles long before the office received the data. We also CLOSED our traverses. If we hit 2 known point nice end of traverse. If there was a significant error, we ran a loop back. My opinion is many good Surveying Procedures are becoming lost knowledge. I doubt many of these GPS Field Crews could run a closed traverse, or even understand the procedures. This is quickly becoming my pet peeve with the next generation of surveyors. I never had to pull a chain, and was resented by some old timers. Maybe I've become the next generation of old timer..lol
I don't understand why your GPS control is spaced so far apart. Over long distances GPS control is faster, easier, and more accurate, especially with the flat angles of a route. You must be working in an area where clear sky is hard to come by.
I would stay on the grid. I can understand a layperson being confused about grid/ground, but any surveyor worth a lick should understand it and be able to explain it to the other surveyors they work with.
You'd save your firm a whole lot of time and money to hire a consultant like Loyal Olson to straighten it out and teach you have to properly set up and use a Low Distortion Projection. Before you get sued and end up buying a bunch of pipeline better fly a good consultant in.
It's not that hard but you need to understand how a GPS measures the earth in 3D (X,Y,Z) and how the software converts it a mimic a standard plane survey. What it sounds like you are doing is trying to convert back and forth from an SPC and a ground based distance/bearing deal like a plane survey with conventional instruments. This takes some basic knowledge that it sounds like your firm doesn't have. You are not alone, the SPC converted into crap is very common. To bad we can't just put SPC's in the graveyard where they belong. Our current technology if properly used makes SPC's obsolete. It's like your trying to travel from coast to coast but the only way you think you can get there is with steam trains.
One thought on the GPS, if you do the sort of thing you're doing often, bite the bullet and get your own post-processing software and download some base stations of your choice and process them. You can get tighter results and be more confident that your occupations didn't fail. You have a one-minute or more angle bust. Doesn't sound like a lot, but on a long, open traverse, if it's in one place, it could create a nasty kink in your survey and may not be noticeable in the overall length. Finally, if your combined factor is never worse than, say 0.99998 to 1.00002 (20 ppm) just run on grid. Otherwise, you have to think about what factors you use. You don't have low-distortion grid zones set up in NC, do you? That's a very cool option if available.
Make sure any calculations you are making that your caculator is set to U.S. Feet. I've seen errors you describe because the calculator was not set to U.S. Feet.
I agree with Mark. This is very bad field procedures. You should also have a GPS pair at each end of the 2 or 3 mile lines. I would not use opus either. NCGS & DOT have set CORS for VRS all over the state not to mention all the GPS quality monuments that NCGS has set or re-occupied. You should have multipal sessions on each point. If you use under 2 hr. sessions you can check them with OPUS RS. You should call Gary Thompson at NCGS for some advice but remember he is a sitting board member. On the traverse you should leap-frog using 3 tripods and a minimum of 3 d&r sets on traverse points. Check and adjust all equipment. I am not trying to belittle you, just saying what I would do. By the way, NCDOT does projects this long with a single CF and use the coordinates at one monument. Just make sure everybody knows what was done.
get your field crew to measure direct and reverse when traversing. if you have a broken instrument, it will be consistent each time you measure single angles. and measure each one twice. I wouldn't do a 1/2 ac boundary traversing using "topo shots", let alone a miles long route survey.
like deja vu all over again
