The half-step technique answers one question better than any other schedule analysis: when the completion date moved this month, was it because the work went slower, or because the plan was rewritten?
It does that by building an intermediate schedule. Take last month's update, apply only this month's progress (actual starts, actual finishes, remaining durations driven by progress), and recalculate. Compare last month to that half-step schedule and you see the effect of progress alone. Compare the half-step schedule to this month's update and you see the effect of everything else: added activities, changed logic, changed durations, new constraints. AACE Recommended Practice 29R-03 describes it as MIP 3.4, a bifurcated version of the contemporaneous period analysis. Our earlier article, The Half-Step: Telling Real Delay from Creative Scheduling, walks through the mechanics.
CPM Pros has run half-step analysis for both sides: for a general contractor on vertical hospital construction and biomedical tenant improvement work, and for owners on a major transit agency's light rail upgrade and a major airport renovation. The method is the same on both sides. What each side needs from it is not.
What a contractor needs from it
A contractor uses half-step analysis to show that delay was experienced in the work, not manufactured in the schedule.
- Separate the owner's revisions from your own. When the owner adds scope or changes a sequence, the revision half of the analysis shows its effect on the finish. That is the entitlement. Your own revisions, such as compressing a downstream duration to hold a date, show up there too, and they are mitigation, not delay.
- Show the delay in the month it happened. A half-step result for each window, built from updates submitted at the time, is far more persuasive than a reconstruction at closeout. The updates were accepted by the owner; the analysis uses the owner's own record.
- Watch for paper recovery. If an update "recovered" time because durations were shortened, not because work went faster, the half-step shows it. Better to find that yourself than have the owner find it in your request.
On hospital and biomedical work, the revisions that move dates are often outside the contractor's control: owner equipment decisions, design changes in occupied areas, inspection and licensing sequences. Half-step analysis isolates them cleanly.
What an owner needs from it
An owner uses half-step analysis to check whether a contractor's claimed delay is real progress delay or a schedule that was changed to produce one.
- Look for revisions labeled as delay. Added logic, lengthened remaining durations or new constraints in the same update as a delay claim deserve a close look. The half-step separates them from progress so they can be questioned on their own.
- Look for hidden recovery. A contractor who compressed later work to absorb its own early delay, then claims a later owner delay in full, may be double counting. The month-by-month record shows it.
- Check concurrency. When owner and contractor delays fall in the same window, the order of analysis matters. Smaller windows, or stepping through the period, keep one side's delay from masking the other's.
On transit and airport work, with many contractors, operating constraints and owner-controlled interfaces (track access, operational cutovers, agency approvals), the owner's review has to be just as disciplined as the contractor's claim. Half-step analysis gives both a common record to argue from.
What it takes
- The native P6 updates (XER files) for the windows in question, not PDFs.
- The project record for each window: daily reports, RFIs, change orders, correspondence.
- Consistent scheduling options from update to update, or a documented reason when they changed.
Software helps. SmartPM and other tools now run a half-step comparison automatically, and we use SmartPM on large programs. The judgment is still human: which windows to analyze, how to treat concurrency, and which party owns each day.
Where CPM Pros fits
CPM Pros performs half-step analysis for contractors supporting time extension requests and for owners reviewing them, in Primavera P6, fully remote. Send the schedule updates for the period in question, and we will send back a written quote, typically within 3 business days.