Delay Analysis
Using the schedule to prove what caused a delay and how much time it cost.
Quick Answer
Delay analysis is the use of the project schedule to determine which events delayed completion, by how much, and who was responsible. Common methods include time impact analysis, windows analysis, as-planned versus as-built comparison, and collapsed as-built. The results support time extensions, delay claims, and defenses against liquidated damages.
The Full Picture
Delay analysis exists because a late project usually has many causes, and the contract assigns responsibility for each differently. Owner changes may earn time and money, severe weather may earn time only, and contractor-caused delays earn nothing. To allocate time and cost fairly, the parties need an objective way to measure which events actually moved the completion date.
Mechanically, most methods measure effects on the critical path. A time impact analysis (TIA) inserts a fragnet, a small network of activities representing the delay event, into the current schedule update and recalculates to show the effect on completion; it is prospective and common for time extension requests. A windows analysis divides the project into periods and examines how the critical path and completion date moved within each, using contemporaneous schedule updates. As-planned versus as-built compares the baseline with actual performance. Collapsed as-built starts from the as-built schedule and removes delay events to show when the work would have finished 'but for' them.
In practice, the choice of method depends on the contract's requirements, the quality of the schedule record, and whether the analysis is prospective or retrospective. AACE International's Recommended Practice 29R-03 on forensic schedule analysis and the Society of Construction Law's Delay and Disruption Protocol are widely cited frameworks, and ASCE has published a standard on schedule delay analysis. Different methods applied to the same project can produce different answers, which is why method selection is often contested.
Preconstruction sets up every future delay analysis. A baseline schedule with complete logic, realistic durations, and few hard constraints, together with a specification requiring regular updates and a defined TIA procedure, makes delays measurable. A GC that accepts a weak baseline or a vague schedule specification in precon will struggle to prove entitlement later.
Real Examples
Common Misconceptions
People assume: Every delay analysis method gives the same answer.
Actually: Methods differ in whether they are prospective or retrospective and in which schedule data they rely on, so they can allocate delay differently on the same project. The contract, the available records, and accepted protocols guide which method is appropriate.
People assume: Any delayed activity means the project was delayed.
Actually: Only delays to the critical path, or delays large enough to consume available float and become critical, affect completion. An activity with float can slip without moving the finish date.
Frequently Asked Questions
What is a time impact analysis (TIA)?
A TIA models a specific delay event as a fragnet of activities, inserts it into the most recent schedule update before the event, and recalculates the schedule to show the projected effect on completion. It is the most common method for requesting time extensions during a project.
What is a windows analysis?
A windows analysis breaks the project into time periods, usually matching schedule updates, and examines how the critical path and forecast completion changed in each. Delay in each window is attributed to the events that drove the critical path during that period.
What is a collapsed as-built analysis?
It starts with the as-built schedule and removes, or collapses, the activities representing delay events to estimate when the project would have finished without them. It is retrospective and depends on a reliable as-built record.
Which delay analysis method is best?
No single method is best in all cases. Contract requirements, the availability and quality of schedule updates, and whether the analysis is done during or after the project determine the appropriate method. AACE RP 29R-03 and the SCL Protocol discuss the tradeoffs.
Why does delay analysis matter in preconstruction?
Delay analysis relies on the baseline schedule and the schedule specification, both set in preconstruction. A sound baseline and clear update and TIA requirements make later delays measurable and entitlement easier to prove.