Critical path method (CPM) scheduling was first developed in 1956, overThe first published legal decision involving experts testifying on CPM scheduling came out in 1963, over In the 1960's, a total of 39 legal decisions opining on CPM scheduling were published by courts and Likewise, five major categories of methods for comparing schedule delay analysis were all identified by the early
- Time impact analysis
- As-planned versus as-built
- Impacted as-planned
- As-built critical path
- Collapsed as-built
Over the last few decades, the number of variations or subsets of published schedule delay analysis methods increased to eight inand 17 in
Simultaneous to the proliferation of different methods, it has been well established by at least eight published industry studies from 1990 through 2016 that, mathematically, different methods come to different conclusions when applied to the same exact
It is also widely accepted by authorities that courts and boards prefer time impact analysis methods, in other words, methods that utilize the contemporaneous CPM schedule updates as opposed to otherFor example, in a 2008 study, Arditi and Pattanakitchamroon reviewed 64 schedule delay analysis method references in legal cases and ranked them according to legal acceptance, amongst other Arditi and Pattanakitchamroon found that time impact analysis methods had a significantly higher acceptance rate than any other In a similar but more comprehensive study, Dale and D'Onofrio reviewed 180 case references to specific schedule delay analysis methods, but came to a similar conclusion in that time impact analysis was accepted at a rate three times that of any other
However, as a result of the clear industry preference for methods in the time impact analysis category utilizing the schedule updates, the term time impact analysis is frequently applied to a variety of methods. Combining broad use of the term, without any explicit identification of which variation of the method was preferred, created a void in the industry, and the need for an industry standard that identifies best practices. With that in mind, in 2014, the American Society of Civil Engineers (ASCE) Construction Institute formed a committee to prepare a consensus industry standard for schedule delay analysis in accordance with the American National Standards Institute (ANSI). As part of the ASCE/ANSI standard process, the committee included an independent and balanced group of members including owners, contractors, subcontractors, designers, academics, and consultants representing different facets in the industry. The twelve committee members' collective experience includes publication of four books and over 150 publications on the subject. In accordance with ASCE/ANSI policies and procedures, the committee included broad industry participation, with no more than one individual voting member from a firm or organization. Firms and institutions with individuals participating as members of the standard committee include: AECOM, Altran, Berkeley Research Group, Capital Project Management, Inc., Delta Consulting, Exponent, Hill International, Illinois Institute of Technology, The Kenrich Group, Navigant Consulting, Secretariat International, and the Virginia Polytechnic Institute. The standard committee included participation by members from a variety of relevant industry organizations including AACEI, ASCE, the Construction Industry Institute, PM College of Scheduling, and the Society of Construction Law.
The final version of the three-year standard effort included two public comment periods in which 356 public comments were addressed and resolved by the committee. The final version of the standard was approved for publication, and will be available in 2017. The industry consensus standard sets out its aim in the introduction, identifying thatThe standard proceeds to identify 35 guidelines covering principles of CPM schedule delay analysis in eight
- Critical path;
- Early completion;
- Chronology of delay;
- Concurrent delay;
- Responsibility for delay;
- Changing schedules after the fact; and
The guidelines do not apply to any specific method, but represent standard industry practice applicable to any specific delayExamples of industry guidelines in the standard include Guideline 4.1 "Because the critical path is dynamic, delays should be evaluated based on the critical path during each delay," Guideline 7.1 "Delays should be evaluated as they occur in chronological sequence," and Guideline 10.1 Each guideline has commentary associated with it further explaining the guideline.
The standard acknowledges that although its guidelines reflect standard industry practice, they are still subject to exceptions specific to the facts and conditions of an individual project:
The 35 guidelines included in this standard generally reflect best engineering principles associated with schedule delay analysis and reflect standard of practice in the United States construction industry. However, individual cases may not follow the general standard. Parties should check the construction contract carefully for notice provisions, exculpatory clauses, and requirements for proof of delays. \u2026 The application of [the standard guidelines] should be based on the terms of the contract, contract administration, consistency in application, and
In summary, the new ASCE and ANSI national standard fills an industry need by compiling a formal standard of practice that did not previously exist in the industry. It is likely to be used or brought up when there is a question over the standard industry practice in the industry. Now everyone will have a reference to answer that question. In that way, the standard will help the construction industry by minimizing and helping to resolve disputes over CPM schedule delay analysis concepts without requiring judicial determination, leaving parties to focus on factual entitlement disagreements as opposed to analysis method disagreements. It may have taken 60 years, but the construction industry finally has an industry standard governing the use of CPM scheduling in schedule delay analysis.