Tunnel Boring & Heavy Civil Equipment worked example

Maintenance Interval at 7.2% access, lockout, and delay allowance: a worked example in tunnel boring & heavy civil equipment

This worked example runs the maintenance interval numbers for a tougher week than the baseline: 7.2% access, lockout, and delay allowance instead of the typical 10%. Estimate maintenance interval for tunnel boring and heavy civil equipment using production-ready inputs so teams can plan labor hours, schedule the work, or check whether the job fits the available shift time.

The inputs for this scenario

  • Scheduled service work volume per interval: 120 units (held at the documented default)
  • Crew service completion rate: 12 units / min (held at the documented default)
  • Access, lockout, and delay allowance: 7.2 % (the input this scenario stresses; the baseline uses 10)

Working through the calculation

  • The calculation starts from the formula this tool documents: Base maintenance interval time = maintenance interval workload รท maintenance interval completion rate.
  • Required maintenance interval time works out to 10.72 hr at these inputs, and this is the headline figure for the scenario.
  • Base maintenance interval time works out to 10 hr at these inputs.
  • Maintenance interval allowance applied works out to 7.2 % at these inputs.
  • Maintenance interval completion rate works out to 12 pieces / min at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where access, lockout, and delay allowance sits at 10% and the headline result is 11 hr, this scenario comes in 2.55% below the baseline at 10.72 hr.
  • Use it when planning a cutterhead intervention, hydraulic service window, or conveyor maintenance shift and you need to book the excavation stoppage duration realistically. A result at this level usually justifies acting on the stressed input before touching anything else, because every other figure in the table is downstream of it.

Results at a glance

  • Required maintenance interval time: 10.72 hr (headline result)
  • Base maintenance interval time: 10 hr
  • Maintenance interval allowance applied: 7.2 %
  • Maintenance interval completion rate: 12 pieces / min

Run it with your numbers

  • To rerun this with your own numbers, open the live Maintenance Interval calculator, set access, lockout, and delay allowance to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.