Reducing a ground traverse to grid with a combined factor
A link traverse measured on the ground is tied to state plane control. The combined factor is built from the grid scale factor and the elevation factor, and the closure is computed with and without it.
Analyze· about 32 minutes by hand· 6 steps
Given
A three-course link traverse GPS-1, 201, 202, GPS-2, tying two state plane control monuments.
Published grid coordinates, US survey feet: GPS-1 N 1,842,650.22 E 2,315,880.14; GPS-2 N 1,844,215.55 E 2,317,608.90.
Grid azimuths, already adjusted to the control azimuths at both ends: GPS-1 to 201, 45°00′16″; 201 to 202, 50°06′08″; 202 to GPS-2, 48°15′12″.
Measured horizontal ground distances: GPS-1 to 201, 749.58 ft; 201 to 202, 795.20 ft; 202 to GPS-2, 789.61 ft.
Mean project orthometric height 4250 ft above sea level; geoid height at the project −22.4 m; mean earth radius taken as 6,372,000 m.
Grid scale factor for the project area = 0.99995780.
Specification 1:15,000.
Required
The elevation factor and the combined factor.
Grid distances for the three courses.
The closure at GPS-2 and the precision, computed on grid.
What the closure would have been if the ground distances had been used directly.
Adjusted grid coordinates of 201 and 202.
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