Level-loop misclosure judged against a C√M tolerance and distributed
A four-leg differential level loop that fails to return to its benchmark by 0.040 ft. Test it against C√M for two orders of accuracy, distribute the misclosure by leg length, and carry the adjusted elevations round.
Apply· about 20 minutes by hand· 4 steps
Given
A closed differential level loop was run from BM ORCHARD through three turning points and back to BM ORCHARD.
Leg 1, BM ORCHARD to TP-1: elevation difference +12.442 ft, length 0.62 mile.
Leg 2, TP-1 to TP-2: elevation difference −5.371 ft, length 0.48 mile.
Leg 3, TP-2 to TP-3: elevation difference −8.918 ft, length 0.75 mile.
Leg 4, TP-3 to BM ORCHARD: elevation difference +1.887 ft, length 0.55 mile.
The published elevation of BM ORCHARD is 512.408 ft.
The specification for the work is ordinary third-order levelling, allowable misclosure C√M with C = 0.05 ft and M in miles. The client has asked whether the loop would also meet a second-order standard, C = 0.035 ft.
Required
The misclosure of the loop and the allowable misclosure at both standards.
The correction to each leg and the adjusted elevation differences.
Adjusted elevations for the three turning points.
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