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Simple Traverse Calculator

, 18 Feb 2011 CPOL
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Calculate traverse for Surveying or Geologic mapping.

This is a very simple to use macro written in Excel VBA for calculating and redistributing the error vector to close a traverse.

Background

I wrote this program for my geologic field methods class. A traverse is a simple way to plot points of interest on a 2D map. When in the field, you may not have, or want to carry, appropriate surveying equipment or may not need that level of accuracy, so you can pace from point to point measuring the compass bearing and counting number of paces. You must close the traverse by returning to the original (starting) station or point. You will need to have your conversion factor calculated to feet per pace. One way of doing this is measuring out a known distance, say 100 feet, and count the number of paces. Then take 100 feet divided by your count. A pace is two steps. Start with your left and count every time your right foot makes contact with the ground. Also, bearings must be in azimuth (0 to 360 degrees). Refer to any geologic field book for more information.

Using the Code

Download the batch file (SimpleTravCalc1.bas). Open Excel and enable the developer tab in excel options. Click the visual basic button. Right click "This Workbook" and import file.

Once the file is loaded, return to Excel. Click macros and run SimpleTravCalc1. Make sure you start with a blank excel file.

It is easiest to use if you have your notes setup in the same order as the input boxes arise. Below is a summary:

For all traverses

  1. Title of your project

  2. Total number of traverses (each traverse creates a new sheet)
  3. Conversion factor
    1. There is no conversion calculator here. That should be done before entering field.

    For each traverse (for next loop)

  4. Number of vectors in traverse, or number of stations would be the same.
  5. Station occupied (only for first station, this is the point you will close to).
  6. Station sighted
  7. Forward bearing
  8. Reverse bearing
  9. Paces

Below is a sample of a 21 station traverse I recently did and how is set up in my field book.

occupied sighted forward reverse paces
16 101 48 228 12.5
101 14 196 8 8
14 8 355 178 10
8 13 20 197 2.5
13 11 265 79 6.5
11 17 297 112 10.5
17 7 135 315 4.5
7 6 71 250 5.5
6 sd1 310 130 12.5
sd1 19 79 259 6
19 105 285 105 12
105 4 229 49 8.5
4 1 165 345 2.5
1 5 75 249 8.5
5 lp1 201 18 10.5
lp1 18 227 36 11.5
18 3 90 270 13.5
3 15 283 96 5
15 20 155 332 10
20 mh1 36 219 14.5
mh1 16 182 359 6

Here is how to use it for those less inclined to code. If you set up your notes is this manner, you just need to read across from left to right, ignoring the occupied station after the first entry. It will automatically copy down. The angle given, theta_A, is the average of the forward bearing and the reverse bearing in the quadrant of the forward bearing. The next value given is the distance, r, in feet (or whatever your conversion factor was) based on the number of paces; r = (conversion factor)*(number of paces). You will see X and Y components of the vector calculated which necessary for error vector calculation, but will be removed later. After you have typed in all values, you’re done. Let the program continue to work through and the output is a corrected bearing, theat_C, and corrected distance, r_C, after error vector distribution. Now you have a closure error of zero. The most important thing is the percent error. If your error is high, you may want to go traverse your points again and check your bearings. Also, check that your forward bearing minus your reverse bearing is approximately plus or minus 180 degrees. Below is an example of the final product from the data given above.

Occupied Sighted theta_A r theta_C r_C
16 101 48 61.275 48.0394 61.29694
101 14 192 39.216 191.8628 39.23018
14 8 356.5 49.02 356.6523 48.96217
8 13 18.5 12.255 19.38834 12.24979
13 11 262 31.863 261.7947 31.65447
11 17 294.5 51.471 294.5222 51.18664
17 7 135 22.059 134.6468 22.36208
7 6 70.5 26.961 71.01378 27.25318
6 sd1 310 61.275 310.1342 60.87207
sd1 19 79 29.412 79.4772 29.81805
19 105 285 58.824 284.9506 58.30384
105 4 229 41.667 228.3065 41.39813
4 1 165 12.255 162.7177 12.6238
1 5 72 41.667 72.5625 42.18946
5 lp1 199.5 51.471 198.7071 51.48856
lp1 18 221.5 56.373 220.7752 56.10527
18 3 90 66.177 90.24229 66.93403
3 15 279.5 24.51 279.1045 23.67116
15 20 153.5 49.02 152.7902 49.68415
20 mh1 37.5 71.079 38.22963 71.36235
mh1 16 180.5 29.412 178.6954 29.76824
      887.262    
           
           
Excercise 4        
traverse1          
Conversion Factor 4.902      
Error Vector Magnitude 10.97458      
Error Vector Direction 110.5151      
Error Percent 1.236904      

Important!!! This is a very simple macro and still needs much work, especially in error handling and handling user input error. If you screw up, start over. I will do my best to keep developing it until it is something more user friendly and a nicer GUI.

In the future, I will update this page to include code snippets and how they work, especially in error vector calculation and error vector distribution.

Points of Interest

The macro is very simple and not very "pretty." Future developments include a more comprehensive dialog box to include the options for paces or distance (if using a measuring tape). Two other calculators are yet to be written: one to convert from quadrant bearings to azimuthal and one for calculating conversion factor if not yet calculated.

Future development projects hope to include creating false X and false Y coordinates, searching through all traverse worksheets and averaging X Y coordinates for repeated stations in multiple traverses. After false X and false Y coordinates are calculated relative to some (0,0) reference point, inputing GIS coordinates from a GPS receiver, recalculating new coordinates that would fit the GIS. I also hope to rebuild in Python for direct integration with GIS applications.

The overall objective is use statistics to make the best possible map, or locate points as accurately as possible.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

threeCubed

United States United States
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GeneralMy vote of 4 Pinmemberdb_cooper195023-Mar-11 17:25 

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