## 2. Closure

On a closed loop traverse, the sum of the Lats should equal zero as should the sum of the Deps.

Closure condition:

 Equation D-2

Figure D-7
Perfect Closed Loop

Most traverses wonâ€™t close perfectly due to the presence of errors. If the field crew followed careful procedures and compensated distance measurements for atmospheric conditions, only random errors prevent achieving perfect closure:event achieving perfect closure:

Actual closure:

 Equation D-3

Figure D-8
Cumulative Random Errors

 Figure D-9 Linear Closure

The Linear Closure, LC, is the total misclosure distance. It is computed from the Lat and Dep errors:

 Equartion D-4

Traverse precision is a function of the linear closure and the total survey distance. The precision is stated as a relative value, usually as 1 unit of error per D units measured:

 Equation D-5

What is allowable minimum precision? It depends on the survey purpose. Traditional first order surveys have a required precision of 1/100,000; in Wisconsin a property survey must be at least 1/3000. In order to achieve a formal minimum precision, specific equipment and field procedures must be used which match that precision requirement. Achieving a minimum precision should be by design not by accident.