Disruption and lost productivity: the measured mile

Disruption is different from delay. A crew can finish on time and still cost far more than planned because it was stopped, restarted, resequenced or crowded. Disruption claims are about lost productivity, and they rise or fall on labour and quantity records. This lesson explains the measured mile, the method most widely accepted for proving lost productivity, and how both sides should test one.

Learning outcomes

• Distinguish disruption from delay.
• Calculate lost productivity using the measured mile.
• Describe earned value as an alternative method.
• Separate owner-caused disruption from the contractor's own inefficiency.

The lesson

Delay and disruption

Delay moves dates. Disruption reduces productivity. They often come together, but not always: a contractor can absorb a disruption with extra labour and still finish on time, and the extra labour is the claim. CCDC 2-2020 has no separate disruption clause; disruption costs are claimed under GC 6.6 as a change in Contract Price, with the same notice, record and detailed account requirements [1].

The measured mile

The measured mile compares productivity on the same kind of work in an unimpacted period with productivity in the impacted period. The difference, multiplied by the quantity installed in the impacted period, gives the lost hours. It is described as the most widely accepted method, and AACE RP 25R-03 is commonly cited for it; it needs labour hours and installed quantities on comparable work [2].

View the data

Item	Value
Week 1 (unimpacted)	1.22
Week 2 (unimpacted)	1.27
Week 3 (unimpacted)	1.26
Week 4 (unimpacted)	1.24
Week 5 (impacted)	1.55
Week 6 (impacted)	1.68
Week 7 (impacted)	1.62
Week 8 (impacted)	1.55

Earned value as an alternative

Where no clean unimpacted period exists, earned value compares earned hours (budgeted hours × percent complete) with actual hours in impacted and unimpacted periods [2]. Industry studies of productivity loss exist but carry less weight than project-specific evidence.

Testing a disruption claim

• Is the unimpacted period really unimpacted, and is the work comparable?
• Are labour hours and quantities from records made at the time?
• Has the contractor's own inefficiency (rework, crew turnover, learning curve) been removed?
• Is the labour rate the actual rate, not a billing rate?

Northgate worked example

Northgate Distribution Centre (fictional) is a 12,000 m² tilt-up warehouse in Vaughan, Ontario, built by Halvorsen Builders Ltd. (fictional) under CCDC 2-2020, with Ridgeline Architects Inc. (fictional) as Consultant. See the Northgate fact sheet. This course follows one delay claim from first notice to settlement. Ready-for-Takeover (M9) was due Friday, January 14, 2028 and was reached on Tuesday, March 14, 2028: 60 calendar days late. All events, dates and amounts are illustrative.

The mezzanine redesign disrupted Halvorsen's office framing and MEP rough-in crews. Halvorsen claimed 2,210 lost hours at $95 per hour, $209,950, based on the difference between budgeted and actual hours. The owner's representative applied a measured mile instead, using Halvorsen's own weekly labour and quantity records (Figure 1, above).

The first four weeks, before RFI-118, averaged 1.25 labour hours per unit. The four impacted weeks averaged 1.60 hours per unit. Over the 4,300 units installed in the impacted period, that is 0.35 × 4,300 = 1,505 lost hours. Halvorsen's own records then show 831 hours of rework on a framing error and of crew turnover, which are Halvorsen's risk. That leaves 674 hours × $95 = $64,030 (Figure 2).

View the data

Item	Value
Claimed: budget vs actual	2,210 h
Measured mile	1,505 h
Accepted after removing contractor causes	674 h

Your move

If you are the owner

• Require weekly labour and quantity reporting by area. It makes a measured mile possible.
• Ask for the unimpacted baseline. And check the work is comparable.
• Remove the contractor's own inefficiencies. Rework, turnover and learning curve.
• Reject budget-vs-actual claims. They assume the estimate was perfect.

If you are the contractor

• Track hours and quantities by area every week. Without them, no method works.
• Flag disruption as it happens. Notice under GC 6.6 with the first impacted week.
• Choose a clean comparison period. Explain why it is comparable.
• Own your inefficiencies. Removing them yourself makes the rest credible.

Common mistakes

1. Budget vs actual as proof. The estimate may have been wrong.
2. Comparing different work. The measured mile needs like-for-like.
3. No quantity records. Hours alone cannot show productivity.
4. Billing rates instead of cost. Use actual labour cost.
5. Late notice. Disruption is a GC 6.6 claim with the same notice rules.

Quick quiz

1. What is the difference between delay and disruption?

   1. None
   2. Delay moves dates; disruption reduces productivity
   3. Disruption is always owner-caused
   4. Delay is only weather

2. What does the measured mile compare?

   1. Bid and final cost
   2. Productivity in unimpacted and impacted periods on comparable work
   3. Two contractors
   4. Owner and Consultant estimates

3. Unimpacted 1.25 h/unit, impacted 1.60 h/unit, 4,300 units. Lost hours?

   1. 350
   2. 1,505
   3. 2,210
   4. 674

4. Why were 831 hours removed at Northgate?

   1. They were overtime
   2. They were Halvorsen's own rework and crew turnover
   3. They were weekends
   4. They were the owner's

5. What alternative method compares earned and actual hours?

   1. Impacted as-planned
   2. Earned value
   3. Hudson formula
   4. Windows analysis

Show answers and explanations

1. B. Disruption can cost money even when dates hold.
2. B. Same work, different periods.
3. B. 0.35 × 4,300 = 1,505 hours.
4. B. The contractor's own inefficiency is its risk.
5. B. Earned hours = budgeted hours × percent complete.

Key terms

Disruption

Loss of productivity caused by interference, resequencing or interruption.

Measured mile

Comparison of productivity in unimpacted and impacted periods on comparable work.

Earned hours

Budgeted hours multiplied by percent complete.

Productivity rate

Labour hours per unit of work installed.

Unimpacted period

A period of comparable work not affected by the disruption.

References

1. Canadian Construction Documents Committee, CCDC 2-2020 Stipulated Price Contract, GC 6.4 to 6.6 and Part 8. Clause content checked against a publicly posted tender copy; buy the form from CCDC.
2. FTI Consulting, Assessing loss of productivity in construction: the importance of contemporaneous documentation (March 17, 2025), citing AACE RP 25R-03.
3. Miller Thomson LLP, Ontario Court underlines the evidence and analysis required to establish critical path delays (July 2021).
4. BRC, Northgate fact sheet (fictional case study, v1, November 4, 2026).

Verified on November 9, 2026.

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