How do you calculate TBM downtime cost?

Multiply lost tunneling hours by the standby burn rate, then by the attributable downtime share as a decimal, and add the restart and mobilization cost. With 36 hours at $2,800/hr, 80% attributable, plus $18,000 restart, that is 36 x 2,800 x 0.80 + 18,000 = $98,640 total.

What is a good standby burn rate to use for a tunnel boring machine?

It should capture everything that keeps running while the cutterhead does not: idle crew, TBM lease or amortization, backup power, muck logistics on standby, and supervision. On mid-size EPB and slurry machines $2,000 to $4,000 per hour is common; large-diameter urban drives can exceed that.

Why include an attributable downtime share instead of the full hours?

Not every idle hour is chargeable to one cause. If ground grouting was going to overlap the repair anyway, only the net delay is attributable. The 80% share in the default reflects a stoppage that is mostly, but not wholly, driven by the equipment failure.

What is the difference between the variable cost and the restart adder?

The variable cost ($80,640 in the example) scales with how long you are down. The restart adder ($18,000) is fixed: re-pressurizing, re-crewing, and re-mobilizing happen once regardless of whether you lost 12 or 36 hours.

How much does one hour of TBM downtime cost here?

Divide total cost by lost hours: $98,640 divided by 36 hours is $2,740 per hour. That per-hour figure is useful for comparing events of different lengths and for pricing risk in the schedule.

Is downtime cost the same as a delay claim value?

No. This is the direct cost of the event. A full delay claim may also carry extended overhead, liquidated-damage exposure, and knock-on effects on the critical path, which this calculator does not attempt to model.

Tunnel Boring & Heavy Civil Equipment calculator

Downtime Cost Calculator

When a tunnel boring machine stops, the meter never does. This calculator translates a TBM stoppage into a dollar figure by combining lost tunneling hours, the standby burn rate for crew, cutterhead lease and logistics, the share of the delay actually attributable to the failure, and the fixed cost of restarting and re-mobilizing. Project controls managers, TBM superintendents and claims teams use it to price delay events, support extension-of-time claims, and decide whether a spare-parts stockpile is cheaper than a shutdown. On heavy civil jobs where a single day of standby can eclipse six figures, getting this number right is the difference between a defensible claim and a swallowed loss.

What this calculator does

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.
Use it when quantifying a delay claim or evaluating a maintenance window to translate stopped hours into the standby and restart dollars at risk.
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.

Formula used

Total = lost hours x standby burn rate x (attributable share ÷ 100) + restart cost
Per hour = total cost ÷ lost tunneling hours

Inputs explained

Lost Tunneling Hours:
Standby Burn Rate:
Attributable Downtime Share:
Restart & Mobilization Cost:

How to use the result

Use it immediately after a stoppage to quantify the delay for daily cost reports, delay claims, or root-cause reviews, and beforehand to justify redundancy investments.
The attributable share is a judgment call; if fault is contested (e.g. concurrent delay between ground conditions and machine failure) the percentage drives the answer more than any other input and should be evidenced, not guessed.

Current U.S. benchmarks

Steel mill PPI stands at 348.53 (BLS, May 2026), up 6.7% from a year earlier. New factory orders are up 2.3% year over year (Census).

Common questions

How do you calculate TBM downtime cost? Multiply lost tunneling hours by the standby burn rate, then by the attributable downtime share as a decimal, and add the restart and mobilization cost. With 36 hours at $2,800/hr, 80% attributable, plus $18,000 restart, that is 36 x 2,800 x 0.80 + 18,000 = $98,640 total.
What is a good standby burn rate to use for a tunnel boring machine? It should capture everything that keeps running while the cutterhead does not: idle crew, TBM lease or amortization, backup power, muck logistics on standby, and supervision. On mid-size EPB and slurry machines $2,000 to $4,000 per hour is common; large-diameter urban drives can exceed that.
Why include an attributable downtime share instead of the full hours? Not every idle hour is chargeable to one cause. If ground grouting was going to overlap the repair anyway, only the net delay is attributable. The 80% share in the default reflects a stoppage that is mostly, but not wholly, driven by the equipment failure.
What is the difference between the variable cost and the restart adder? The variable cost ($80,640 in the example) scales with how long you are down. The restart adder ($18,000) is fixed: re-pressurizing, re-crewing, and re-mobilizing happen once regardless of whether you lost 12 or 36 hours.
How much does one hour of TBM downtime cost here? Divide total cost by lost hours: $98,640 divided by 36 hours is $2,740 per hour. That per-hour figure is useful for comparing events of different lengths and for pricing risk in the schedule.

Last reviewed 2026-05-12.