Two practical level-book modes
Simple mode compares an observed existing level with an optional design level at every point. It suits reduced levels already established from approved survey information. Laser / height-of-instrument mode starts from a benchmark reduced level and backsight. The tool calculates the height of instrument, subtracts each staff reading and then compares that reduced level with an optional design level.
point existing RL = height of instrument − staff reading
signed difference = design RL − existing RL
Cut and fill convention
Existing above design is labelled CUT; design above existing is labelled FILL. The table prints the action as text, so meaning never depends on colour. A point inside its optional tolerance is labelled WITHIN TOLERANCE. A blank design level remains a level record and is labelled Not assessed.
The sums shown for cut and fill are sums of individual vertical differences, not earthwork volumes. To estimate a volume, combine representative level differences with an appropriate area, grid, cross-section or surface method.
Worked height-of-instrument example
A benchmark reduced level of 100.000 m and backsight of 1.500 m produce a height of instrument of 101.500 m. A point staff reading of 1.700 m gives an existing reduced level of 99.800 m. If design level is 99.820 m, the point requires 20 mm of fill before considering any entered tolerance.
CSV and local saving
Use Point, Existing level, Design level, Tolerance, Notes headers for simple imports. Use Point, Staff reading, Design level, Tolerance, Notes for laser imports. Exported files include calculated existing levels and text actions. Set the measurement system before importing because a CSV is interpreted in the currently selected units. Quoted notes containing commas are supported.
The worksheet automatically retains work in local browser storage and also provides an explicit Save locally action. Nothing is uploaded by this tool. Browser data can still be cleared, lost or isolated between browser profiles, so export important records and follow the project’s controlled record procedure.
Field limitations
Do not treat the output as an approved survey record without the required observations, checks, closures, signatures and review. Confirm benchmark identity and stability. Check the instrument before use and after knocks or moves. Keep the staff vertical, use appropriate sight lengths, observe the required precision and apply any curvature, refraction, settlement or correction procedure specified for the work.
Frequently asked questions
What sign convention does the level book use?
When existing level is above design level the point requires CUT. When design level is above existing level the point requires FILL. The displayed quantity is the absolute vertical adjustment.
How is height of instrument calculated?
Height of instrument equals the benchmark reduced level plus the backsight reading. Each point reduced level then equals height of instrument minus its staff reading.
Are level-book rows uploaded?
No. Calculation, CSV import and local saving happen in the browser. Data remains on the device unless you deliberately export a file or copy the result.