Tunnel Boring & Heavy Civil Equipment worked example

Downtime Cost at 58% attributable downtime share: a worked example in tunnel boring & heavy civil equipment

Suppose attributable downtime share falls to 58%. This page works the full calculation at that level so you can see exactly which result moves and by how much. Estimates the cost of a TBM stoppage from idle hours, standby burn rate, the share attributable to a given cause, and a fixed restart cost.

The inputs for this scenario

  • Lost Tunneling Hours: 36 hours (held at the documented default)
  • Standby Burn Rate: 2,800 $/hr (held at the documented default)
  • Attributable Downtime Share: 58 % (the input this scenario stresses; the baseline uses 80)
  • Restart & Mobilization Cost: 18,000 $ (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Total = lost hours x standby burn rate x (attributable share รท 100) + restart cost.
  • Total downtime cost works out to 76,464 $ at these inputs, and this is the headline figure for the scenario.
  • Downtime cost per unit works out to 2,124 $ / piece at these inputs.
  • Variable downtime cost works out to 58,464 $ at these inputs.
  • Fixed downtime cost adder works out to 18,000 $ at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where attributable downtime share sits at 80% and the headline result is 98,640 $, this scenario comes in 22.48% below the baseline at 76,464 $.
  • It computes the total dollar cost of a TBM or heavy-civil downtime event as variable standby burn plus a fixed restart adder, and expresses it per lost tunneling hour. 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 downtime cost: 76,464 $ (headline result)
  • Downtime cost per unit: 2,124 $ / piece
  • Variable downtime cost: 58,464 $
  • Fixed downtime cost adder: 18,000 $

Run it with your numbers

  • To rerun this with your own numbers, open the live Downtime Cost calculator, set attributable downtime share to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.