Time, money is linked to building a construction project. Construction projects schedules are a budget or estimate for how a contractor expects to spend time building a project. Since the 1960s, critical path analysis (CPA) has grown in use in the construction industry as a tooling contractor to plan and budget the time available to construct a project.

Construction is not a time and costs fixed industry. Like budget or plan, there is always the risk that unexpected eventsdisrupt the plan and result in an overrun—a construction schedule delay in the context of the construction schedule.

Construction schedule delays, in turn, can lead to disputes and claims. Disagreements about the causes of delays, their impact on the construction process, and which contracting party must bear the consequences can become contentious. However, by working with and analysing CPA construction schedules, often it is possible to quantify and determine with reasonable certainty the cause of and responsibility for delays occurring on a project. Courts, boards, and agencies in many jurisdictions favour using CPA construction schedule analysis in deciding legal claims for construction delays.

Forensic Construction Schedule Delay Methods

The growth in CPA construction schedule for the past fifty years has brought several different methodologies for analysing construction delays. It also has given rise to a specialised discipline—forensic construction schedule delay analysis. Forensic schedule delay analysis is the study and investigation of events using CPA scheduling methods to establish the cause and extent of delays and resolve construction delay claims through negotiations or legal proceedings. It is a field for experts trained and experienced in CPA scheduling.

Various approaches to analysing construction schedule delays have evolved over the years, but no standard method has emerged.  AACE International (formerly the Association for the Advancement of Cost Engineering), in its Recommended Practice 29R-03 Forensic Schedule Analysis (2011), sets out basic technical principles and guidelines for CPA scheduling in forensic schedule analysis.  It offers nine “method implementation protocols” for analysing delays. 

Although there is not a consensus, forensic schedule delay analysis methods can be grouped into four prominent families to measure delay days.

As-planned vs as-built

The measure of delays that occur on the days they occur and delays that have accrued at a specific point compared to the plan.

Contemporary period analysis (Windows)

Measured combination of accrued delay to the start of an evaluation period and projected delays through the project’s end.

Retrospective time impact analysis

Measures projected delays at the start of an evaluation period as reflected in CPA schedule updates and calculate additional delay at the end of the project by inserting a fragnet (a network fragment, or a portion of the project schedule that relates to the specific delay) into the evaluation period, and

Collapsed as built.

Compares actual dates and events with after-the-fact assumptions about what hypothetically should have been planned.

Selecting the method of evaluating a delay is essential because various forensic schedule delay analysis methods will produce different results even when applied to the same set of facts. Moreover, each method has its strengths and weaknesses.  Further, practical considerations may render an analytical method of useless or infeasible in each situation.  For instance, contractual constraints, such as a contract clause requiring the use of a particular method to analyse project delays,  the project records and source schedules available, the cost and time to prepare a forensic schedule delay analysis, or the forum in which the delay analysis will be presented can make one method more suitable than another.

Pros and Cons of General Methods of Forensic Schedule Delay Analysis

Because no consensus exists regarding a single method of analysing schedule delays to be followed in every situation, selecting the analytical method most appropriate for a given situation is vital. The general strengths and weaknesses of the primary methods of analysing schedule delays always should be weighed.  Using the four general methods of delay analysis as a framework, some basic pros and cons for each analytical approach can be identified.

As-planned vs as-built

Comparison of an as-built schedule to an as-planned schedule

• Relatively easy to perform.
• Susceptible to manipulation through the selection of as-built data
• Simple to present and easy to understand.
• Not generally accepted by many courts
• It can be persuasive if performed correctly.
• Causation based on experts’opinions.
• Useful when data is limited.
• Does not measure concurrent delays.

     Not suitable for complicated projects or projects built significantly different than planned.

Contemporaneous period analysis (Windows)

Measures accrued delay at the start of the evaluation period and projected delays to the end of the project.

• Accurate when there are regular CPA schedule updates.
• It can be challenging to present and is expensive and time-consuming to perform.
• Measures each delay and documents causation.
• CPA updates may not be accurate.
• It can be performed on an ongoing project.
• May not adequately consider concurrent delays.
• Difficult to manipulate and accepted by many courts and agencies.

Retrospective time impact analysis

Measures projected delay as reflected in CPA schedule updates and inserts fragnet into evaluation period to calculate delay at the end of the project.

• Useful for analysing complicated CPA schedules.
• It can be challenging to present and is expensive and time-consuming to perform.
• Measures each delay and documents causation.
• Can be subject to excessive decision making by analyst.
• Can be performed on an ongoing project and measure evolving delay.
• Can be susceptible to manipulation.
• Can determine concurrent delays.

Accepted by many courts and agencies.

Collapsed as built.

Compares actual dates and events with after-the-fact assumptions about what should have been planned or could have been done.

• Easy to present and understand “but for”analysis.
• Reconstructing an as-built schedule is costly and time-consuming and may be after-the-fact analysis.
• Theoretically measures concurrent delays by separate “collapse runs” for contractor delays and owner delays.
• Limited acceptance by many courts or agencies
• Offers documented evidence of causation.
• Susceptible to manipulation
• Requires substantial decision making by analyst.

Conclusion

Deciding which method of CPA schedule delay analysis is the most suitable for evaluating a construction delay is crucial in evaluating the cause and impact of a given delay.  While no consensus exists regarding a standard analytical method appropriate for every situation, the pros and cons of various methods should be kept in mind.  When an unexpected event disrupts and delays a construction project, using a sound analytical method to identify the cause and quantify the extent of the delay will be essential for negotiating a fair result or for obtaining a fair outcome in arbitration or litigation.

CIBER  performs a whole range of forensic cost and time analysis for arbitration, adjudication, and mediation, including.

• audit of construction costs,
• analysis of historical costs,
• development of cost models for alternatives.
• examination of disallowed cost
• Cost loaded schedules.
• Production rate analysis
• Cost to completion analysis
• Trend forecasting
• Cross-examination of entitlement against all common contract forms#
• Filtering out duplicated or miss allocated costs,
• analysis and identification of disallowed costs.
• Examination of unit costs and production rates for various construction activities
• Tracing and validation of time and expense claims over above contractedsums.