Prepare a BS / IS / FS field book
Start with a BS on a known benchmark and finish with an FS. Each intermediate sight belongs to the current instrument setup. A turning point can use one row with both FS and the next BS, or two consecutive rows with the same point name: FS first, BS second. The old HI reduces the turning point; its new BS establishes the next HI. No rows are sorted or silently discarded.
Optional columns: distance (cumulative route chainage), bs_distance, fs_distance, known_rl (independent control), recorded_rl, recorded_hi, rise, fall and remarks. Common headings such as Station, Backsight, Foresight, Chainage, RL and HI are accepted. Recorded HI on a paired FS+BS row means the new HI; recorded rise/fall refer to the incoming sight. Leave absent readings blank; zero is a valid reading.
Read the arithmetic and benchmark checks
For a completed run, ΣBS − ΣFS = Σrise − Σfall = final raw RL − starting RL. Intermediate sights affect individual levels and rise/fall steps but are excluded from BS/FS totals. Both methods can agree even when a field reading is wrong. Compare recorded values and known benchmarks, then inspect the original book and the setup interval reported for a control residual.
The NOAA Manual of Leveling Computation and Adjustment explains leveling computation and adjustment. The MnDOT Surveying and Mapping Manual provides field procedures, vertical-control checks and sight-balance guidance. Select tolerances from the requirements for your own survey.
Distribution and supported formats
Misclosure is raw closing RL minus known closing RL. Distance distribution applies −misclosure × (chainage − starting chainage) / total route length. Blank starting chainage means zero. Supply increasing chainage at all turning points and the end; an intermediate chainage must lie within its setup interval. Unlocated intermediate sights retain raw RL only. Equal-per-setup distribution assigns a share to each completed setup; intermediate sights inherit the correction at the setup’s start. Internal benchmarks are checked, not held fixed.
Input is UTF-8 delimited text with decimal numbers or scientific notation. Excel workbooks, angle/DMS formats, decimal commas, instrument binary formats and automatic unit detection are not supported. All dimensional columns share one unit. The workbench does not apply instrument, rod, refraction or orthometric corrections or perform a constrained network adjustment. Raw observations and closure remain visible after distribution.
Common questions
How do HI and rise/fall reductions compare?
HI equals the starting or turning-point RL plus its backsight. Each subsequent RL is HI minus the intermediate sight or foresight. Rise/fall compares consecutive rod readings within each setup; the methods should produce the same raw levels.
What is the misclosure sign?
Misclosure is raw closing RL minus known closing RL. The optional cumulative endpoint correction has the opposite sign. Arithmetic agreement alone does not prove the field observations are correct.
How is misclosure distributed?
Choose no adjustment, equal correction per completed setup, or correction proportional to supplied cumulative route distance. Equal-per-setup intermediate sights inherit the setup-start correction. Distance mode leaves intermediate sights without chainage unadjusted. Internal benchmarks are checked but not constrained.
Are level books uploaded?
No. Parsing and reduction run in a local browser worker. CSV, JSON, SVG and full printable HTML reports are generated locally.