Free Web Tool

Differential Leveling

Reduce a level book — Height of Instrument (HI) and Rise & Fall methods, arithmetic check and loop closure with an optional known final BM.

Inputs

elevation of first station (m)
m, for closure check
Format per row: id, type, reading [, type, reading...]. Types: BS back-sight, FS fore-sight, IS intermediate. A turning point has both FS (closes prev. setup) and BS (opens next setup) on the same row.
Method & checks
  • HI method: HI = RL_prev + BS; RL_next = HI − FS (or − IS for intermediate, RL stays @ HI − IS).
  • Arithmetic check: ΣBS − ΣFS = Last RL − First RL.
  • Loop closure: e = Computed Last RL − Known closing RL. Tolerable ≈ 12 mm·√K (K = km of leveling).

Results

ΣBS
ΣFS
ΣBS − ΣFS
Last RL − First RL
Arithmetic Check
Closure error
StaBSISFSHI / RiseRL