AEC definitions
A baseline schedule is the contractor's logic-based plan, accepted by the owner, that becomes the measuring stick for progress and delay. Dates and relationships are frozen in that version. Monthly updates copy it and add actuals. A baseline that was never reviewed is a weak baseline when a claim arrives.
Definition
Specifications usually require a critical path schedule within a set number of days after notice to proceed, with a narrative, calendars, and resource logic the spec names. The architect or owner returns comments. The accepted version is the baseline. Changing it later without agreement is not an update. It is a new plan. Recovery schedules and revised baselines happen after major changes, and they should be labeled as such. The look-ahead the superintendent uses each week is a window on the baseline, not a replacement for it.
In depth
A finish on or before the contract date, logic that a builder recognizes, procurement for long-lead items, and ties to the schedule of values if the spec requires cost loading. A pretty bar chart with every activity linked only to the finish is not reviewable.
Constraints and lags should be explained in the narrative. Hidden constraints are how float is manipulated.
The baseline file is stored and not overwritten. Each update is a copy with actual start and finish dates and remaining duration. Logic changes are listed. Without that discipline, there is no as-planned versus as-built comparison.
Rejection comments should be closed before the team treats the schedule as approved. Using an unaccepted schedule for months helps no one in a dispute.
Cost-loaded baselines tie activities to the schedule of values. Percent complete should match the pay application. Two different percent-complete stories is a controls failure.
A schedule that shows work complete and a pay app that does not, or the reverse, needs a reconciliation before the owner certifies.
After a large change order or a recovery plan, the parties may adopt a revised baseline. Label the revision.
Do not call it update 14 if the logic was rebuilt. Time extensions belong in the same record.
Examples
The contractor submits a CPM 30 days after notice to proceed. Comments are resolved. That file is saved as the baseline.
Update 4 records actuals. The original baseline file is unchanged and is the comparison.
A major owner change resets the plan. The parties approve a revised baseline and stop measuring against the first one.
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