
The figures need to describe the actual work, not just add up. You are tracing quantities, inclusions and price assumptions back to their basis.
Construction estimate reviewCompare the excavation entry with the route and trench section. Inspect the entry you suspect, then correct it.
Trace a suspicious quantity or allowance back to the physical boundary it is supposed to represent.

Select a marker to connect the physical work to the estimate.
Tomas Castelazo · CC BY-SA 3.0 · resized; numbered markers added.
Source: https://commons.wikimedia.org/wiki/File:114_inch_pipe_installation.jpg
Licence: https://creativecommons.org/licenses/by-sa/3.0/

Illustrative scene. Use the lesson figures and records for measurements.
Select a suspected entry. Reconcile it to the drawing or work record before changing the estimate.