Hi All

Gross errors in measurements will manifest themselves in a traverse misclose. These gross errors are typically a distance and/or bearing error. How would you identify individual bearing and distance measurement errors by analysing a traverse misclose.

Regards

Mat

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I can offer one method of reducing error while traversing in the field - a low, stabile prism will keep residuals low and errors within budget. One way to do achieve these repeatable results is by using The Marksman Prism Tripod, a product specifically designed for accurate measurement which can be used with any type of prism for Total Station measurement. Check out www.themarksman.ca

Nice.

Alexander,
Yes, I agree with you. I didn't intend to say anything that would suggest that a PLS should not use his professional judgement & experience to determine which adjustment method is most appropriate for a given situation. Least squares are definitely not a cure all & can never replace good survey practice & sound judgement. It seems, however, that a great many things in the natural world & mathematics vary with the square root of something. Least squares gives you positional tolerance & not "error of closure", which is most appropriate with more complex adjustments of networks. Perhaps I am missing something but I thought we were talking about finding an error in a normal rectilinear traverse as run with a total station. Back when I was still using a manual theodolite, I often turned angles more than once. Not to increase the precision but as a check against a bust. Essentially, what we are looking for here is a bust. When you find the "bust" the only thing I know to do is to then verify it in the field. Should the traverse still not close, it isn't rocket science, as the saying goes, you just have to keep looking until you find the reason. I recall a party chief that was fired from a prominent local surveying co. because he failed to notice his theodolite was out of adjustment & turning bad angles. I don't like the idea of trying to "hammer fit", as it is called, an adjustment on the computer to try to compensate for bad equipment or bad field work. This type of thing rarely happens with high order work as the specifications require that multiple angles (sets) be turned & other checks that are designed to prevent such errors. High order work is now done with GPS, of course, which is a whole new ball game.
Charles, I used to be a PLS in North Carolina before returning to the UK some five years ago so completely understand your comments. I now deal predominantly with surveyors who only seem to know of Leadt Squares as it is the only option on their PDAs. Least Squares is ideal for GPS networks (I even remember the calculations for "Arbitrary adjustments of a centerpoint polygon" which was applied to taping or chaining networks). I assure you that I am not as ancient as that makes me seem.
If I do not find that error I can assure you that it will appear at the time to make me appear most inept
Alex,
I get misunderstood a lot. I never had any perception of you as being ancient. Today is my 70th. birthday so I would find it very difficult to accuse anyone else of being "ancient". To add a bit of color if you will permit me, I was once invited aboard the then British flag ship, HMS Juno, by the crew. I was stationed aboard the USS Bon Hommie Richard CVA 31, with VA 94 & both ships were in Hong Kong at the time. No offense taken but my name is actually Charlie, not Charles as is the usual case.
Thank you for your comments & it has been a pleasure conversing with you.
Will,
I don't want to rain on your parade or anything. If that sort of thing works for you, then do it. Yes, you are right, with the precision of modern surveying instruments there is relatively little adjustment to be made. With the type of boundary work I usually do, I generally adjust a rectilinear survey to a GPS baseline established using static observations with a GPS base unit. My clients generally don't care what they own on a geodetic grid, they want to know what they can build or how much corn they can plant so the plat reflects the rectilinear survey. Reference coordinates for selected control points are given in State Plane coordinates. I feel that a good boundary survey today should be tied to a geodetic reference datum for obvious reasons. Pocket size computers or whatever have been around for a long time. No problem if you have one that runs on a cell phone. I have a HP 50G with a surveying module & my instrument has on board computing capabilities that will do most anything. I rarely use either. I prefer to collect data while in the field & concentrate on doing good field work & finding boundary control & evidence of occupation. GPS files are usually converted to RINEX format for post processing. I personally don't like anything "microsoft" for surveying & only use it because there is no other alternative. I will get rid of it as soon as something else becomes available. Windows is for social networking & playing movies.

Most of my work was relative to engineering surveying which included setting up of and monitoring control. All these points were initially set up by GPS and then Traditionally traversed in for greater precision. I wouldn't leave site unless I new everything that I had established was right. I too used to use programmable calculators (Ti 83 to be more precise) but then I discovered the power of Android (Not MS) which has a better visual affect and all the data can be sent out via the internet for further processing if needs be.

Just about everybody carries a mobile phone around with them these days.

Yes, I too carry a mobile phone. I use it as a phone. Different strokes for different folks. I don't do any staking until control has been established & verified. All the computations I need for engineering stakeout or construction are done before I go in the field, except checks that are to detect any problems or errors. It is usually close to nightfall when I quit for the day. I am not inclined to do calculations after dark. Not that my approach is better than anybody else's or anything but it has served me well for many years and has a near perfect tract record. My system works for me & I hope yours works as well for you. All I can say is good luck! I am self employed which means that if I buy equipment, it must pay for itself. These days I don't do a lot of construction staking & I don't miss it a bit. I was associated with an outfit recently that had all the state of the art equipment you can imagine but nobody knew how to operate most of it. I am considering post processing my own GPS data. The most important thing for me is producing quality work second to none. I must be doing something right as I get a lot of repeat business.

Unfortunately a lot of the work I did was night shifts, i.e Road Closures, Tunnelling, Bridge and Gantry work where survey and setting out during day time shifts was sometimes impossible. I'm not saying what I'm doing with mobile phones is the best thing since sliced bread, I've just put it out there as another alternative. Something that's always at hand if needs be. All the software that you use on your desktop Charlie could be re- written to go on a mobile phone either as a native app or cranked onto a server and run as a web app. The only thing restricting mobile phones these days is the screen size. The last instrument I used (About 10 years ago now) was the Leica 1200 series and even then that was configured for uploading CSV files and had Bluetooth built in. MS Office is now available on mobile phone's and Bluetooth is a function that is considered quite old, but you could in reality interface your mobile phone with instruments for data exchange. I've got a feeling that this has been the case for sometime now?

I was wondering what kind of work you were doing. Alternatives are a good thing and the nature of the job often dictates the best approach. The essential keys to turning out quality work with the type of jobs I have been targeting lately are to leave no leaf unturned in your plat/legal research & quality geodetic control. I have seen cell phone communication & blue tooth used in the field and it surely has applications, particularly with larger organizations. I don't think it would be a wise move for me at this time.

Thanks for taking the time to give me some feed back Charlie.

Will.

This has been a very interesting and helpful discussion to read! I am a 4th year geomatics student and currently studying the Least Squares method. Thanks!

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