Profile levelling reduced to a profile and a grade line
Reduce a profile level run with intermediate foresights to ground elevations at six stations, then compute a grade line at -1.20 percent and the cut or fill at each station.
Apply· about 22 minutes by hand· 6 steps
Given
A profile level run along a proposed roadway centerline from station 10+00 to station 15+00, run from BM-7 and closed on BM-8. Distances in feet; stations are 100 ft apart.
Elevation of BM-7 = 528.64 ft. Elevation of BM-8 is unknown and is to be carried through.
Setup 1: backsight 6.42 on BM-7. Intermediate foresights (ground rod readings): 4.8 at 10+00, 5.6 at 11+00, 7.1 at 12+00. Foresight 8.94 to TP-1.
Setup 2: backsight 3.17 on TP-1. Intermediate foresights: 2.4 at 13+00, 4.0 at 14+00, 5.5 at 15+00. Foresight 6.28 on BM-8.
Rounding convention: benchmarks, turning points and heights of instrument to 0.01 ft; ground rod readings and ground elevations to 0.1 ft, which is all a rod held on soil can support.
The proposed grade line passes through elevation 530.30 ft at station 10+00 and falls at 1.20 percent.
Required
The reduced profile notes, including the elevation of TP-1 and BM-8.
Ground elevation at each of the six stations.
Grade elevation and the cut or fill at each station.
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