Description

Collapsed as Built, also known as but-for analysis as built but for, is a modelled technique based on scenario simulation. This simulation is carried out in critical path calculation software such as MS Project or Primavera P6. With this method, it is possible to determine the earliest date on which milestones could have been completed if the delays of one of the parties had not occurred.

It is a static logic method because the relationships in the model do not change during the different stages of analysis. Methods with dynamic logic are considered the most suitable for an expert report. This method is based on as-built logic, so it can be used to carry out a forensic analysis.

The difficulty of this method lies in creating a properly linked model with the as-built dates and all delay events that occurred. It is not advisable for very long projects with many activities and without very clear and defined construction logic.

To carry out a delay analysis using this methodology, the following steps should be followed:

  • Locate the as-built programme and identify delays, activity durations and start and finish dates.
  • Start creating the model in CPM software using the actual activity durations and the delay events that occurred, identifying who was responsible for them. A seven-day calendar can be used so that all calculations are directly in calendar days. In addition, it is common for activities to be carried out outside the originally planned working period. It must be considered that anomalous results sometimes occur; for example, when an activity started on a Friday and finished the following Monday, the assigned duration will be four days, even though work actually took place on only two days. The system tends to balance itself, because other activities may be scheduled, once collapsed, in a period that the project calendar considered non-working.
  • Once the model has been created with the delay events, the duration of the delays that are the responsibility of one of the parties is changed to zero in order to calculate the earliest completion date if those delays had not occurred.
  • The same process must be carried out for the delays of the other party.

Strengths

  • It is a robust method that, if carried out correctly, allows good expert analyses to be prepared.
  • It considers all delays that occurred on the project, making it possible to assess the impact of subcritical paths.
  • An electronic baseline or contemporary updates are not required.
  • It is conceptually easy to understand and present.
  • It allows concurrent delays to be analysed and the impacts of each party's delays to be identified once the model has been created.
  • Few delay analysis specialists apply this method.
  • It is a technique that can be applied while the project is still in progress to calculate extensions of time or penalty forecasts.

Weaknesses

  • It does not consider the contemporary programmes of the project.
  • Creating the model requires a great deal of work, a high level of detail in the as-built information and very experienced specialists in software use and delay analysis.
  • Creating the logic to replicate the as-built conditions requires subjective decisions that may not coincide with the contemporary schedules.
  • It is susceptible to intentional or unintentional manipulation during the modelling process.
  • It ignores the prospective critical paths in contemporary programmes and the critical decisions that may have been made based on them.