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I successfully used the COGO traverse tool to create a polygon for a piece of property described in a legal description. My issue arose because it did not line up with data I already have of the area. I did not expect it to line up perfectly, but I did expect it to be closer than it was. The projections for all of the data in the map are the same so I'm not sure if it is because there is a specific projection used for legal descriptions or what. If anyone has experience with COGO and legal descriptions I would appreciate the help.

I am using ArcMap 10.2.

The data I already have for the area is vast, but I am using a buildings feature class (polygon features), and a quarter section feature class (polygon features) from the datasets in our database. I also have a georeferenced image in my map that shows the property boundary surrounding the particular apartments I am looking at. This image is based on the legal description and comes from the engineers who worked on the apartment complex. Again, all data is set to the same projection.

My steps include:

  1. Creating a polyline shapefile and a polygon shapefile.
  2. In my editor toolbar I went to editing options and changed the "Direction Type" to Quadrant Bearing, and the "Direction Units" to Degrees Minutes Seconds. I checked the "Ground to Grid Connection" box, then I made the "Distance Factor" 1 since my projection is in State Plane US Feet.
  3. I started an editing session and began using the COGO traverse tool to create a polyline feature that according to the legal description commences at the corner of section 28 (remember I have quarter section map, which has the referenced section) and ends at the "True Point of Beginning."
  4. From the True Point of Beginning I use the COGO traverse tool again to create a polygon for the property boundary based on the legal description.

If more details about my steps are still needed please let me know, but for now I am trying to keep it simple to avoid boring or dissuading the reader from reading.

Also, for information purposes, this project was given to me to see if it was possible to use GIS to map Legal Descriptions. So far I can't report yay or nay because yes I successfully mapped using a legal description, but no it did not end up where it should. It is very very close, but the boundary I COGO'ed does not cover all the apartments in my building feature class that it needs to. It just needs to move to the south about 100 ft. I am having a hard time believing the legal description is right and our building feature class is wrong because that would mean all the data we have in our database is wrong. I am also not convinced that the legal description is wrong. So that leaves me with thinking I made a technical user error. I can't make any recommendations until I figure out what the issue is and whether it can be fixed.

This is a screenshot of what I have been working on. The polygon is supposed to surround the smaller buildings in the middle.

map screenshot

This is a screenshot of the legal description I have been using.

metes & bounds description

  • 1
    What GIS software & version are you using? You can edit your Question to include this important detail. – PolyGeo Jan 2 '14 at 22:43
  • Also, I recommend that you list the steps that you have taken so that a potential Answerer just has to let you know the ones he/she thinks that you have missed. – PolyGeo Jan 2 '14 at 23:25
  • Also need to know what is your other data. When there is a conflict between two datasets, you should look at both... – radouxju Jan 3 '14 at 9:29
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    I would uncheck the "Ground to Grid Correction" and try it again. – klewis Jan 4 '14 at 1:05
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    Thank you for your comments. I understand the issues with the georeferenced image. It was only in place as a guide. I have looked over the ESRI resource and it looks like I am missing the actual Ground to Grid Correction. The legal document I was given does not have basis of bearing or convergence angle for directions and scale factor for distances. I am looking into acquiring this from my employer. Also, I will try to add some images when I can. – ZPembi Jan 6 '14 at 20:07
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Legal plans (plats) and legal descriptions are not in any projection (grid) system; they are on a local, ground-based plane. Hence the need for grid-to-ground and ground-to-grid conversions. As a minimum, there are usually scaling and rotation issues to deal with.

So, it is quite possible that neither GIS nor legal description are wrong.

Once we get more details and give more advice, you'll probably find you can use your GIS.

Now, based on your mapped area and legal traverse, it looks like your traverse does indeed close but it needs to swing clockwise, about the commencing section corner, by a significant amount. The swing will probably be the difference in the so-called "basis of bearing" between the GIS map and the land survey.

In case it helps, I have just used Copan -- a free Windows package, for legal survey traverses -- on your data:

Checking Bearing-Distance Traverses at 20:51 on 6 Jan 2014

MapTrav file  C:\Users\Martin\Documents\Copan\pine-ridge.mt  

 1) Map Traverse Results  [1 - 1]
    Leg Count             20
    Total Distance   2134.00

    Coordinate Misclosure
    N    -0.02       Dist          0.02   <-- Warning: Large Misclosure!
    E     0.01       Brng   S28°19'34"E
    Relative precision  1 : 105415   

                               Start or  Curve
         Bearing   Distance    To Point   Code
                                      1 
     S62°38'44"E      41.22           2       
     S 8°16'40"E      58.01           3       
     S36°39'50"E      37.14           4     BC
     N53°20'10"E      50.00           5     CC
     S 6°44'26"E      50.00           6     EC
     N83°15'34"E      73.05           7     BC
     S 6°44'26"E      35.00           8      C
     N73°20'20"E      35.00           9     EC
     S16°39'40"E      43.41          10     BC
     N73°20'20"E     200.00          11     CC
     S53°12'28"W     200.00          12     EC
     S36°47'32"E      36.59          13       
     S 3°29'58"E      42.66          14       
     S29°29'29"E     237.38          15       
     S20°05'15"E     249.68          16       
     S69°51'47"W     125.25          17       
     N19°59'03"W     142.92          18     BC
     S70°00'57"W      50.00          19     CC
     N 7°06'29"E      50.00          20     EC
     N82°53'31"W      57.65          21     BC
     N 7°06'29"E      50.00          22      C
     S53°52'07"W      50.00          23     EC
     N36°07'53"W     500.73          24     BC
     N53°52'07"E      30.00          25      C
     N59°20'49"W      30.00          26     EC
     N30°39'11"E     198.42           1       

   Curve results
      Beg        Cent       End          Arc      Chord     Radius      Angle
        4           5         6        52.43      50.06      50.00   - 60°04'36"
        7           8         9        48.92      45.03      35.00   + 80°04'46"
       10          11        12        70.27      69.91     200.00   - 20°07'52"
       18          19        20        54.90      52.18      50.00   - 62°54'28"
       21          22        23        40.81      39.68      50.00   + 46°45'38"
       24          25        26        34.97      33.02      30.00   + 66°47'04"

   NB: The Total distance (quoted above and used to determine Relative precision)
       excludes curve radials and includes curve chords.
       The Perimeter Total (below) excludes both radials and chords but includes curve arcs.

   Perimeter
    segments    1844.11
        arcs     302.29
       Total    2146.40

        Area         181568 (sq. units)

Although it warns of a "large" misclosure = 0.02 ft, this represents a good relative precision = 1 : 105415

Note, I began from the "true point of beginning", where the loop begins-ends, and assigned point numbers 1-26 including curve centers. It gives the area, as a bonus.

If/when you know the bearing correction and ground-to-grid scale factor, they can be applied.

PS: I know a lot about Copan because I was a developer.

I'm guessing that, if the first course of the legal description is along the section line (due West) yet its stated bearing is N87°52'23"W, then the bearing correction should be -02°07'37" (the difference).

What happens if you try that value?

Ultimately, you need proper, professional confirmation. At least try http://surveyorconnect.com/ for further advice.

  • This is interesting. What is Copan's purpose exactly? I see it gives you curve results, and perimeter totals. Is that what you would use Copan for? – ZPembi Jan 9 '14 at 18:30
  • That particular module, Map Check, is for checking legal plans/descriptions for accurate closure and for consistency of stated curve and area details -- many organizations use it primarily for that. However, it does a lot more: field survey calculations, coordinate transformations, ad hoc cogo, traverse adjustments -- things that land surveyors and civil engineers like to do. gis.stackexchange.com/questions/12105/… – Martin F Jan 9 '14 at 20:28
  • Late to the party, but I wanted to point out the bearing correction above is on the right track but not quite there. Picking up the basis of bearing from that first call is a good idea since it isn't explicitly stated, but the section line probably isn't due west. Since you have a section grid that matches your data, what you really want is the difference between that line and the first call since they should be the same. The grid correction tool gives you a couple of ways to do this. Scale factor is another issue as no length is given for the section line to compare to the grid's length. – Chris W Apr 24 '14 at 4:42
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  1. Don't base your investigation on just one survey. You should enter 30 to 50 of them - at least. It is quite possible you found the one bad deed in the bunch.

  2. It is possible that the surveyor has his own version of the section lines that do not match your section lines. Check other deeds in the same quarter section and see if they claim the same bearing along the section line. If so, it may be YOUR section lines that are in error.

  3. Or the surveyor created a typo in the deed - it happens. He meant to say South West, but printed North West instead. You will find this out, again, by looking at other deeds that give bearings along the section line.

Good Luck

  • Thanks for your help. Why would I want to look at that many surveys? That seems like a lot to me. The survey shape and everything looks right. Its just the commencing line. I think I have figured out my problem though. I just don't have a scale factor on the survey they gave me. So I think thats my problem. I used a 3 degree adjustment on it and that looked a lot better, but I still need to know the surveyors basis of bearing, which is not on the document I have. – ZPembi Jan 9 '14 at 18:37
  • It does seem excessive, but then there are different cadastral systems: those where the latest plan is guarenteed to be correct (the Torrens system), and those where endless searches for historic deeds are often required (what brenth is describing). – Martin F Jan 9 '14 at 20:37
  • I just suggested trying a -02°07'37" adjustment (at end of my answer) then noticed you tried a -3° adjustment! – Martin F Jan 9 '14 at 21:01
  • martin f, thanks. Where did you come up with a -02˚07'37"? That is a lot more exact than my -3˚ adjustment. – ZPembi Jan 10 '14 at 18:19
  • @ZPembi - (I didn't notice your last question 'till just now. I'd get a notification if you'd prefixed my name with "@") That's the difference between an E-W section line N90˚00'00"W and the first course N87°52'23"W (i did say in my answer). However, i'm only guessing. – Martin F Jan 31 '14 at 4:20

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