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# Compass Traverse Calculations

Hey,

I'm a GISc student at Texas A&M Corpus Christi. I am trying to learn how to calculate a traverse using a compass vs. using a normal total station. I'm using a Azimuth hand traverse and when I do the calculations my traverse isn't closing by 15 feet. The total length for the traverse was only 300 feet. it closes when I use a total station. So I wondering if I have to use a different equation? My professor said yes it is a different equation but never really told me what it was. So seeing if yall know.

Thank yall in advance!

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### Replies to This Discussion

Hi Mitchell,

First what is a Azimuth hand traverse???.Are you saying your using a hand held compass. There is only one way to calculate Azimuth and Bearings alone with a distance. You can use vectors,but your still doing basically the same math. if you were using a compass on a transit or a surveyors peep hole compass you may be able to read your azimuths more closer than the hand held.Your error is on how close you can read the different direction of your lines A compass does not  measure DddMmmSss like a Total Station or a transit, so your math will not be as defined. The art of surveying with a surveyors Transit using a compass is a fading art and is not understood as in years past. Following one's foot steps of yesterday may fade with the art of surveying with a compass. If you have a old surveyor Transit using it's compass your traverse would close better. There is a lot one can learn on how surveyors used  a compass and what effects it. all this helps in following a old survey done with one.

Hi Mitchell,

Do not know if this will help,you have more and likely seen all of this.  And I do not know what kind of compass you are using as I assume you are asking about analog device.

https://web.statler.wvu.edu/~ddean/CE305/Disk1/6%20TraversingSurvey...

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The thing to remember about a compass survey is that if you get a bad compass reading, the error stays in that one leg. If you bust an angle in a transit survey, the error is carried through the entire traverse. You may have a bust in your compass survey. Have you compared the angles in the transit survey with the angles calculated from the compass survey?

First of all you have got to understand the accuracy limits of your equipment.  A good hand compass - one that can read to a degree or two - is hard to use to start with.  It must be held very steady, it must be level for each reading, it must be kept away from metal ( old frontier surveyors had to have some one hold their rifles while taking a reading) and today it can't be within 5 feet of a cell phone - think of the EM emissions and magnets in them.   Also, you say your closure if off by 15 feet... Well is it off by 15 feet left or right of your point of beginning? Or is it long or short of your point of beginning?  You don't say how you are getting your horizontal distances when using your "Azimuth"?  Are you just stepping it off or pacing?  A wooden yard stick? Lastly, I find it odd the your prof says there is a different formula at this level of instruction.

Good Luck,

Kevin

Hi Mitchell,

I 've read your question over and over again, and i'm still trying to figure out what do you actually meant by ' different equation' and the    compass you mentioned  is it a magnetic Primatic  compass? if it is so..  A compass will only give the reading to the nearest 30' and the best you can estimates is 15' .... there are other factors which can easily  affects the reading such as metal, the pivot become blunt.... the reading of a compass may varied  from other compasses and this why our Surveys department have classified this method is only fit to used for 3rd class  or below....  and we have ceased to use this since most of our field technician is equipped  with TS and GNSS...  one thing though  you can not compare the accuracy  with TS .. should use Abney Level for measuring Vertical angle and steel tape for measuring distances ...this should improve the traverse closure.. hope this help

All the above is basically true but remember, you have an angular closure that is independent of the summation of the latitudes & departures. How do the angles from the compass traverse compare with the angles from the transit (theodolite) traverse? Have you checked (remeasured) the compass bearings? Did you say the traverse was 300 feet? That is like one part in 20. You did something wrong! The crudest measurements imaginable would produce a better closure than that!

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