Recovering a Slipping Schedule Without Cutting a Witness Hold Point
Your firm is the owner's engineer on a 24-month, USD 18.6 million expansion. At the end of month 9 the controls report shows PV = USD 7.2 M, EV = USD 6.1 M and AC = USD 6.8 M. The critical path runs through mechanical completion of the utility building, which has 4 working days of total float.
Two events land in the same week. The switchgear factory acceptance test is pushed back five weeks by the vendor; that switchgear is needed before energization and before any HVAC commissioning. The owner simultaneously adds an analyzer shelter worth roughly three weeks of work on the same path.
The contractor proposes to recover by moving the electrical crews to 6 x 10-hour shifts, and by deleting the Level-2 owner witness hold point on the 11 kV cable hi-potential and partial-discharge tests, arguing that the contractor's own quality assurance will cover it. The contractor's QA manager supports the proposal. The owner's operations team is under pressure to hit a contractual start-up date that carries liquidated damages.
1. Calculate CPI, SPI, two EAC forecasts and TCPI, then state what those figures do and do not tell you about this project.
Read the worked answer
CPI = 6.1 / 6.8 = 0.90, so about 10 percent cost-inefficient. SPI = 6.1 / 7.2 = 0.85, about 15 percent behind on the cost-weighted schedule measure. Percent complete is EV / BAC = 6.1 / 18.6 = 33 percent.
Forecast 1, budget-based: EAC = BAC / CPI = 18.6 / 0.90 = 20.7 M, a variance at completion of about -2.1 M. Forecast 2, both cost and schedule performance persisting: EAC = AC + (BAC - EV) / (CPI x SPI) = 6.8 + 12.5 / (0.90 x 0.85) = 6.8 + 16.3 = 23.1 M. Reported as a range, 20.7 to 23.1 M, is the honest answer.
TCPI against the budget: (18.6 - 6.1) / (18.6 - 6.8) = 12.5 / 11.8 = 1.06, so the remaining work must run about 6 percent more efficiently than budget, which is possible but not consistent with current trends.
What the figures do not tell you: SPI is a cost-weighted ratio and is unreliable at one-third complete, and it says nothing about which activity is late. The real schedule signal is the five-week switchgear slip against four days of float, which is roughly 21 working days of negative float before the owner's added scope.
2. Evaluate the two proposed recovery measures: the 6 x 10 shift pattern and the deletion of the Level-2 witness hold point.
Read the worked answer
On the shift pattern: sustained 10-hour days over several months increase fatigue-related errors and incident rates, and productivity per hour falls, so the crew does not deliver 50 percent more output. It also raises cost against a project already at CPI 0.90, and may conflict with the contract's working-hour provisions and local labor rules. It is defensible for a short, well-defined campaign on the true critical path with a fatigue management plan, not as a blanket remedy.
On the hold point: a Level-2 owner witness point is a contractual quality control, not an optional courtesy. Deleting it changes the inspection and test plan and requires a formal concession, approved by the owner and, where relevant, the insurer and the authority having jurisdiction. On an 11 kV hi-potential and partial-discharge test the risk is dielectric failure at energization, which is an arc-flash and fire hazard to people, not a paperwork issue. The contractor's QA cannot substitute for the witness function that the contract assigned to the owner.
As owner's engineer I would not instruct a contractor to skip a hold point. The alternatives are to resequence testing per circuit, add a second test crew with weekend working, or bring the witness in earlier, not to remove the control.
3. What do you recommend, and what do you put in writing?
Read the worked answer
Recommend a combined response, and put the whole of it in the weekly report and the decision log.
Schedule: treat the switchgear slip as the dominant event. Submit a time-impact analysis and an extension-of-time claim if the vendor or owner carries that risk, rather than trying to absorb five weeks into four days of float. Resequence the analyzer shelter so it runs off the critical path, for example pre-assemble the shelter off site and tie in later. Commission the HVAC on temporary power if that is technically and safely feasible. Add a second test crew to run the cable tests in parallel, with the owner's witness present for each.
Quality: refuse the deletion of the hold point in writing, cite the inspection and test plan clause, and state that any concession would need a documented deviation approved by the owner and, where applicable, the authority having jurisdiction.
Reporting: give the owner a forecast completion date, a cost at completion range of 20.7 to 23.1 M, the options with their cost, schedule gain and risk, and a clear recommendation. Record the switchgear slip date, the notice date and the correspondence reference, because the notice timing drives the contractual entitlement. Do not re-baseline without a formally approved change.