Concurrent Delay Analysis: Part 3
By: Charles Choyce
In parts 1 and 2, I discussed the definitions and general standards set forth by the Association for the Advancement of Cost Engineering International (AACEI) Recommended Practice to determine concurrent delay. In this post, I will illustrate challenges confronted in attempting to apply those concepts, which are by their nature very fact intensive.
Let us use as an example a typical office building with concrete foundations and a structural steel superstructure. The baseline schedule provided that the critical path ran through the construction of the foundations, followed by the start of structural steel erection. However, due to delays in resolving structural steel design problems by the owner’s structural engineer, the project’s critical path shifted to the structural steel design. The delay in resolving the design issues delayed by 100 days the fabrication of steel necessary to commence the erection, resulting in the project completion being delayed by 100 days. At the same time, the contractor completed the foundations 20 days later than planned.
In this example, the 20-day delay by the contractor in completing the foundations is not a concurrent delay. Here, the owner’s design delay created relative float, or slack time, for the foundations against the new critical path driven by the design and fabrication of the steel. Instead of being a critical path delay with 20 days of negative float, the foundations have 80 days of relative float against the new critical path of 100 days as a result of the steel design delay. At the end of the period under analysis, the critical path as depicted in the schedule would be driven by the design, fabrication, delivery, and start of structural steel erection. Assuming no further delays, the project would be delayed 100 days, and the contractor would be entitled to a compensable 100-day time extension for the entire period of delay.
In the above example, it is apparent what was delaying the critical path. The example is relatively easy to understand because of the large amount of relative float created by the steel design delay, which delays the start of steel erection to August 9, 2010, as compared to the May 20, 2010, completion of the foundations.
Longest Path Theory
The above example illustrates what is commonly referred to as the “longest path theory,” as noted in AACEI Recommended Practice 29R-03 for Forensic Schedule Analysis. Under this theory, only delays on the critical path should be considered in determining concurrent delay. With the evolution of CPM scheduling, it is possible to analyze what path or chain of activities is the critical path to project completion. Thus, in our above example, applying the longest path theory, no matter when the foundations completed, whether on schedule or in actuality 20 days late, the project would not have completed any earlier because of the owner’s design delay.
In an unreported decision in a bench trial in Baltimore, the court determined that although the owner had caused 100 days of delay to the project on what was determined to be the critical path, a secondary path of delay caused by the contractor would have delayed the project 98 days. Despite the fact that the critical and secondary paths of activities were nearly identical, and one could suggest that the delays were therefore concurrent, the court—using the longest path approach—held that the contractor was entitled to the full 100-day time extension, despite its own delays that were nearly equal to the critical path delay. In this case, the court apparently ruled that even slight adjustments to the schedule determine the outcome. This case illustrates the challenges in determining whether a delay is concurrent or not using the longest path theory.
In the next post, I will discuss other analytical techniques that may be utilized in determining concurrent delay.
The views expressed in this article are those of the authors and do not necessarily reflect the position or policy of Berkeley Research Group, LLC.