(and the two types that are used…)
Delay analysis is the practice of investigating why construction projects are late.
Construction projects are well known for falling behind schedule and being subjected to lengthy delays. These delays can have a significant impact on all parties involved in the project and often have severe financial implications. From the late issue of construction drawings, building materials arriving late, other contractors preventing access, and poor weather conditions, there are many factors that can lead to delays on site.
Unfortunately, even small delays to critical tasks can have a major impact on a construction project. Establishing the cause of the delay and understanding who is responsible can be a complicated process. Independent Delay Experts and Claims Consultants are often engaged to assess the circumstances of the delay and to establish which party is liable. To reach their decision there are several tools available, the analysts select a delay analysis methodology to apply to the case.
The Society of Construction Law’s Delay and Disruption Protocol states that there are six main delay analysis types, these are:
- Impacted As Planned Analysis
- Time Impact Analysis
- Longest Path Analysis
- As-Planned Vs As-Built Windows Analysis
- Time Slice Windows Analysis
- Collapsed as Built
Impacted As Planned and Time Impact Analysis are considered prospective methodologies, as they examine the delays when they occur. As-planned vs as-built windows, longest path, time slice windows, and collapsed as-built delay analyses are classed as retrospective methodologies. In construction disputes and claims, retrospective methodologies are the most commonly used types of delay analysis; we’ll examine each in more detail below.
As-Planned Vs As-Built Windows Analysis
The as-planned vs as-built windows analysis is the most used delay analysis method in the UK and Ireland, it is favoured by tribunals due to its fact-based approach utilizing cold hard evidence. This method arguably delivers the best results as it dives deep into the project records, carefully examining the contemporaneous details of the project.
As its name suggests, this delay analysis compares the events that occurred during the construction project with the events that were planned at the start of the project. So, the actual events are compared with the planned version of events. This enables analysts to establish precisely where the actual critical path was contemporaneous with the delay events.
This method closely examines the delays by breaking the project down into time periods or windows. Unlike other types of delay analysis, this method doesn’t rely heavily on programming software. However, despite being the most commonly-used method, it does have drawbacks. The biggest issue experienced using the as-planned vs as-built windows analysis is data availability. Accurate project records such as progress meeting minutes, contractor weekly reports and payment valuations are essential when using this evidence-based approach to investigate delays.
Time Slice Windows
The time slice windows approach breaks the entire project down into small windows or slices of time. Like the As Planned vs As Built analysis the expert determines the actual critical path through the project. Examining each window of time, the delay expert establishes any changes to the critical path and the extent of delay to completion. The analyst can measure the delays and review of the contemporaneous project records allows for a better understanding of the events that led to the delay, and their impact on the rest of the project. The time slice method requires a well-developed baseline programme and progressed programmes throughout each windows slice period. It can be very time consuming and costly method of analysis.
Collapsed As-Built
When an as-planned programme isn’t available for the project, a collapsed as-built delay analysis may be used. This method takes the as-built programme (which often needs developed first) and removes the delay events from the timeline one by one showing the impact of each event on a ‘but for’ basis. This helps to determine a theoretical completion date that would have been met if the delay events hadn’t occurred. This approach is rarely used as it is time-consuming and has limited reliability due to the subjective approach required.
Time Impact Analysis
The Time Impact Analysis method, also referred to as TIA, is a technique that forecasts or predicts the effect of a delay event on a project’s completion date. This method involves the insertion of a ‘ Fragnet’ (group of new activities indicating delays or changes) into the most recent programme update prior to the delay event’s occurrence. This allows the team to determine the impact of a delay activity or series of delay activities on the project’s completion date.
The TIA is a prospective methodology and thus is typically used by Contractors Teams during the project to forecast the effect of the delay just before or as it is happening in order to receive an extension of time to the Completion date. This contrasts with a retrospective method described above, which analyzes delays after they have occurred or after project completion.
Final Thoughts
Delays in construction are common and can cause significant issues, including financial losses, for everyone involved in the project. The SCL Delay & Disruption Protocol provides six types of delay analysis that can be applied to establish the cause of delays, but choosing the right delay analysis method is crucial. As outlined above in my opinion, there are only two methods used, Time Impact Analysis and a Retrospective Windows Analysis.
During live projects the site team (planner or scheduler) will utilize a Time Impact Analysis ‘TIA’ to apply for an extension of time under the contract. This prospective form of analysis is also prescribed by the NEC form of contracts.
Forensic Delay Experts, whom are typically involved in dispute resolution after project completion favour a retrospective analysis. Due to its robust, evidence-based approach, and precise analysis of time windows, as-planned vs as-built windows analysis is the most widely used and accepted method.