Tunnel Boring & Heavy Civil Equipment worked example

Rework Cost at 50% reject rate applied: a worked example in tunnel boring & heavy civil equipment

Suppose reject rate applied falls to 50%. This page works the full calculation at that level so you can see exactly which result moves and by how much. Estimates rework cost for heavy civil fabrication from defective joint count, per-joint repair cost, applied reject rate, and fixed re-inspection setup.

The inputs for this scenario

  • Defective Weld Joints: 60 joints (held at the documented default)
  • Repair Cost per Joint: 950 $/joint (held at the documented default)
  • Reject Rate Applied: 50 % (the input this scenario stresses; the baseline uses 70)
  • Re-Inspection Setup: 12,000 $ (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Total = defective joints x repair cost x (reject rate รท 100) + re-inspection setup.
  • Total rework cost works out to 40,500 $ at these inputs, and this is the headline figure for the scenario.
  • Rework cost per unit works out to 675 $ / piece at these inputs.
  • Variable rework cost works out to 28,500 $ at these inputs.
  • Fixed rework cost adder works out to 12,000 $ at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where reject rate applied sits at 70% and the headline result is 51,900 $, this scenario comes in 21.97% below the baseline at 40,500 $.
  • It computes the total cost of a weld rework batch as the variable per-joint repair cost times the effective reject rate, plus a fixed re-inspection setup, and the cost per defective joint. When the numbers land here, the stressed input is the lever to work; the walkthrough above shows exactly how much each output recovers as it climbs back toward the baseline.

Results at a glance

  • Total rework cost: 40,500 $ (headline result)
  • Rework cost per unit: 675 $ / piece
  • Variable rework cost: 28,500 $
  • Fixed rework cost adder: 12,000 $

Run it with your numbers

  • To rerun this with your own numbers, open the live Rework Cost calculator, set reject rate applied to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.