Automatic Closure Settings

As a rule, you will want to set up your traverse data for automatic closure settings. This will reduce the editing and allow you to easily check your closures as you enter and edit traverse data. Here are several options you will want to consider.

Using Closed Loop Tolerance and Closing Back on the Initial Point

The following example, TPC uses the Closed Loop Tolerance to determine it is a closed loop because the last point (6) is nearly the same as the initial control point (1).

Point  Type  Grid Bearing  Grid Dist  Horiz Angle  Northing  Easting  Description

1                                                  0.000     0.000   

2      BS    N000'00"E    100.00                                    

3            N9000'00"E   100.00     9000'00"    0.000     100.000 

4            N000'00"E    100.00     9000'00"    100.000   100.000 

5            S9000'00"W   100.00     9000'00"    100.000   0.000   

6            S000'00"E    100.00     9000'00"    -0.000    0.000   

Using this method, TPC will automatically establish the closure type and the closing point. If you choose to check and/or balance angles, you will need to provide a closing angle.

Add a Closing Angle

In the following example, the last shot (7) includes just an angle. TPC will assume this is the closing angle turned at point 6 with the correct closing bearing/azimuth being from 1 to 3.

Point  Type  Grid Bearing  Grid Dist  Horiz Angle  Northing  Easting  Description

1                                                  0.000     0.000   

2      BS    N000'00"E    100.00                                    

3            N9000'00"E   100.00     9000'00"    0.000     100.000 

4            N000'00"E    100.00     9000'00"    100.000   100.000 

5            S9000'00"W   100.00     9000'00"    100.000   0.000   

6            S000'00"E    100.00     9000'00"    -0.000    0.000   

7                                     9000'00"    0.000     100.000   

Using =[point label] in Descriptions

You can also include =[label] in the descriptions of your closing points. This provides added flexibility in closing out on the initial occupied point or backsight (Closed Loop) or any other points in the survey (Closed Point-to-Point).

Most data collectors will let you add an '=' to a description, so this is a very generic solution. In addition, the =[label] format creates a premanent record of the points you closed out on.

If you are using Least Squares, you can also specify the '=' character for redundant observations. You now have the best of both worlds - 1) automatic closure checks and 2) redundant observations.

Closing Out On the Backsight

In the following example, the closing points 15 and 16 each contain information in the Description about the points they are closing back into. As a result,

Pointe="mso-tab-count:1">  Type  Grid Bearing  Grid Dist  Horiz Angle  Northing  Easting  Description

11                                                 0.000     0.000   

12     BS    N000'00"E    100.00                                    

13           N9000'00"E   100.00     9000'00"    0.000     100.000 

14           N000'00"E    100.00     9000'00"    100.000   100.000 

15           S9000'00"W   100.00     9000'00"    100.000   0.000    =12

16           S000'00"E    100.00     9000'00"    -0.000    0.000    =11

 Using this method, you can close out on the initial point 11 or the initial backsight, 12. Both are considered to be a closed loop and will generate an area.

Ending with a Closing Angle

In the following example, the last shot (26) records just a closing angle. Using the descriptions, TPC deteremines that the resulting closing bearing/azimuth should be the same as the correct closing bearing/azimuth from points 22 to 21.

Notice that point 26 is not recomputed since it contains only a horizontal angle. As a result, is has the same coordiantes as point 25. Since the coordinates of 26 do not come into play in the closure, their values don't matter.

Point  Type  Grid Bearing  Grid Dist  Horiz Angle  Northing  Easting  Description

21                                                 0.000     0.000   

22     BS    N000'00"E    100.00                                    

23           N9000'00"E   100.00     9000'00"    0.000     100.000 

24           N000'00"E    100.00     9000'00"    100.000   100.000 

25           S9000'00"W   100.00     9000'00"    100.000   0.000    =22

26                                    9000'00"    100.000   0.000    =21

Related Topics

Traverse Closure
Closure View
Balancing Coordinates
Balancing Angles