A measured mile analysis is a method of quantifying lost labour productivity on a construction project. It compares the productivity achieved on comparable work during an unaffected (or less affected) period or area with the productivity achieved on the same work while it was disrupted. The difference shows how many extra labour hours the disruption appears to have cost. On its own it measures the loss; it does not prove what caused it or that the loss is recoverable.
Why it carries weight
A properly prepared measured mile analysis is widely accepted as one of the most reliable ways to quantify productivity loss, where the project has records good enough to support it. Its strength is that it uses the project’s own data rather than industry factors or another project’s performance.
The SCL Delay and Disruption Protocol (2nd edition, 2017) generally prefers project-specific productivity studies, such as the measured mile, over comparisons with other projects or published industry studies. AACE International Recommended Practice 25R-03, Estimating Lost Labor Productivity in Construction Claims, also discusses the measured mile as a leading project-specific method, while recognising that there is no single method the whole industry agrees on. In practice the right method depends on the records available.
The measured mile formula
- Baseline rate = labour hours in the comparison period ÷ quantity installed in the comparison period
- Expected hours = quantity installed in the disrupted period × baseline rate
- Excess hours = actual hours in the disrupted period − expected hours
- Net hours claimed = excess hours − hours caused by matters that are not the other party’s responsibility
The same scope of work and the same categories of labour hours must be used on both sides of the comparison. Where the work mix differs materially, calculate separately for each type of work rather than using one blended rate.
How a measured mile analysis is done
- Choose the work. Pick an activity with a clear unit of measure, such as metres of cable, tonnes of steel or square metres of blockwork, that was carried out both with and without the disruption.
- Collect the records. Timesheets or labour allocation by activity, installed quantities, daily reports and site diaries, week by week.
- Select the comparison period or area. It does not have to come before the disruption. It can be earlier, later or in a different part of the site. What matters is that the work is comparable and the data are reliable.
- Test that it is representative. Check that the sample is long enough and large enough, that crew size and skill, access, complexity, methods and working conditions are similar, that the learning curve has passed, and that it is not an unusually productive spell. Explain any differences.
- Calculate the rates and the excess hours using the formula above.
- Adjust. Remove hours caused by the contractor’s own problems, weather it carries the risk for, its own rework, and any other causes that are not the other party’s responsibility.
- Demonstrate causation. Link each disruption event, such as late design information, restricted access, resequencing or congested work areas, to the affected weeks through contemporaneous records.
- Price the net hours. Use the costs actually incurred, which may include wages, employer on-costs and verified overtime, on the basis the contract allows. Check that the same hours are not already paid through variations, acceleration, preliminaries or prolongation costs.
A worked example
Before the disruption a contractor pulled 4,000 m of cable in 2,000 labour hours: 0.50 hours per metre. During the disrupted period it pulled 6,000 m in 4,500 hours: 0.75 hours per metre.
- Expected hours: 6,000 m × 0.50 = 3,000 hours
- Excess hours: 4,500 − 3,000 = 1,500 hours
- Less contractor-caused rework (illustrative): 200 hours
- Potentially claimable: 1,300 hours
The hours per metre rose by 50%, which is the same as output per labour hour falling by a third. The two percentages describe the same loss in different ways and should not be mixed up. The 1,300 hours are recoverable only if causation, contractual entitlement and the costs incurred are proved, and only if the rework hours were not already excluded from the data.
Measured mile and delay analysis are different questions
A measured mile analysis measures inefficiency: the extra resources used to do the work. Delay analysis measures time: whether events moved the critical path and the completion date. Work can be disrupted without delaying completion, and a project can be delayed without productivity falling. A measured mile does not, by itself, support an extension of time.
Evidence checklist
- Timesheets with labour allocated to activities or cost codes
- Installed quantity records for the same activities and periods
- Daily reports, site diaries and photographs
- Instructions, RFIs, design issue registers and variation registers
- Access, sequencing and work-front records
- Notices and correspondence about the disruption events
Common challenges
- No clean period. A least-impacted period can be used, but it is not the same as an unaffected one. Because some loss may already be in the comparator, the result is likely to understate the total loss. Heavy theoretical adjustments to fix this reduce reliability.
- Learning curve. Early productivity is usually low, so the choice of comparison period can distort the result.
- Different work. Comparing straight runs with congested areas, or different trades, invites the reply that the work itself caused the difference.
- Poor allocation of hours. If timesheets do not separate the activity’s hours from other work, the figures will not survive scrutiny.
- Causation. The analysis shows that productivity fell, not why.
What contractors, employers and lawyers should test
- Contractors: whether labour and quantity records are traceable to the same activities, and whether the comparison period will stand up to challenge.
- Employers: whether the baseline is representative, whether contractor-caused losses have been removed, and whether the hours are already paid elsewhere.
- Lawyers: how the loss is linked to specific events, whether notice requirements were met, and whether the contract allows recovery of the costs claimed.
When a measured mile is not possible
If there is no usable comparison, other methods include earned value based comparisons, work sampling, programme-based analysis, comparison with a similar completed project, cost-based approaches and, as a last resort, published industry studies. Each has evidential limits, and those relying on assumptions rather than the project’s own records generally carry less weight. The choice depends on the records available and the circumstances.
Frequently asked questions
What is a measured mile analysis in construction?
It compares labour productivity on comparable work in unaffected or less affected conditions with productivity during disrupted work. The difference is used to estimate the extra labour hours the disruption appears to have cost.
How do you calculate lost productivity using the measured mile method?
Divide the comparison period’s labour hours by its installed quantity to get hours per unit. Multiply that rate by the quantity installed during the disruption, subtract the result from the actual hours, then remove hours caused by matters that are not the other party’s responsibility.
Can a measured mile be used without an undisrupted period?
Yes. A least-impacted period or a comparable work area can be used, but any loss already in the comparator means the result may understate the total loss, and adjustments must be explained.
Does the measured mile period have to be before the disruption?
No. It can be before, during or after the disrupted work, or in another location, provided the work and conditions are comparable and the records are reliable.
Does a measured mile analysis prove an extension of time?
No. It quantifies productivity loss. Entitlement to more time depends on a delay analysis showing an effect on the critical path and completion.
How Solvix can help
Solvix International prepares and independently reviews measured mile analyses, including selection and testing of the comparison period, productivity calculations, causation links and pricing of the net hours, as part of our disruption analysis and quantum analysis services. Where time is also in dispute, we combine it with delay analysis. Send a short brief or book a free 30-minute call.
