Planner answers

What is a half-step (bifurcated) windows analysis?

Short answer: A half-step splits each window into two moves: first the previous update is re-scheduled with only the new progress, then the revised logic and durations of the new update are applied. The first step measures delay from progress; the second measures the effect of programme revisions.

In a contemporaneous windows analysis (AACE 29R-03 MIP 3.3) each window compares two consecutive updates. If the contractor also changed logic or durations in the later update, part of the movement of the finish date is caused by those revisions rather than by what happened on site. The half-step (MIP 3.4) separates the two:

  1. Previous update - finish A.
  2. Half-step: previous logic and durations with the progress (actual dates and remaining durations) of the current update - finish B. B − A is progress delay.
  3. Current update - finish C. C − B is the effect of revisions.

Engineers increasingly ask for the half-step programmes as XER files. Chronaxis produces them for every window, ready to import into P6.

Read the windows analysis guide →

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