a. Loop Traverse

 

Figure I-5
Bearing Traverse Example

 

Previously computed unadjusted latitudes and departures are:

Line Bearing Length (ft) Lat (ft) Dep (ft)
AB S 68°05'35"W 472.68 -176.357 -438.548
BC N 19°46'00"W 216.13 +203.395 -73.093
CD N 45°55'20"E 276.52 +192.357 +198.651
DA S 54°59'15"E 382.24 -219.312 +313.065
 

sum:

1347.57 +0.083 +0.075

 

(1) Compute preliminary coordinates from the raw latitudes and departures:

(2) Determine latitude and departure closure errors:

Lat err = NA' - NA = 500.083' - 500.000' = +0.083'

Dep err = EA' - EA = 2000.075' - 2000.000' = +0.075'

Note that these match the latitude and departure column sums above.

(3) Compute and apply corrections to the coordinates using the Compass Rule, Equation (I-3).

Line AB

Because point A is a control point, its coordinates are not modified. The corrections are applied to the line's endpoint, point B.

Line BC

Remember to include the corrections for the previous line.

Line CD

Line DA

The corrected preliminary coordinates match the beginning coordinates of point A.

These coordinates also match those computed in the Coordinates section.