Mastering Delay Analysis in Construction: Critical Path, Concurrency, and Gantt Charts Explained

What is a Project Schedule/Program?

Example:

Imagine a construction project to build a small office building. The critical path includes key tasks like laying the foundation, erecting steel beams, and installing the roof. If the foundation work is delayed by 5 days, every subsequent task on the critical path, like installing the steel beams and roofing, is also delayed by 5 days, ultimately delaying the project's completion.

A project schedule, also known as a program, outlines the tasks necessary to complete a construction project within a specified timeframe. It breaks the project down into smaller tasks, each with a start and finish date, and includes resource allocation such as labour, equipment, and materials.

One of the most commonly used methods in project scheduling is a Gantt chart and the Critical Path Method (CPM). The critical path is the longest sequence of activities that must be completed on time for the entire project to meet its deadline. Tasks on the critical path have zero slack, meaning that if any of them are delayed, the overall project is delayed by the same amount of time.

Therefore, every project must understand the program and the critical path that drives the finish date. Several commonly available software tools can help develop a project program, identify the critical path(s), and manage the changes.

Why is Project Schedule and Program Important?

The importance of a project schedule in construction cannot be overstated. It serves multiple essential functions:

Coordination and Communication: The project schedule provides a single source of truth for all stakeholders, including contractors, subcontractors, clients, and suppliers. By outlining deadlines, dependencies, and milestones, it ensures that everyone understands their roles and responsibilities.

Progress Tracking: The schedule serves as a benchmark for comparing actual progress with planned progress. When deviations occur, project managers can pinpoint delays and adjust resources to prevent further disruption.

Claim Support: The project schedule becomes a key piece of evidence in disputes or claims. It demonstrates whether delays were caused by external factors, client actions, or contractor inefficiencies.

Example:

In the office building project, if the delivery of steel beams is delayed due to a supplier issue, the project schedule will show that this delay affected the critical path. Although this event impacts the critical path task, i.e. the activity “Steel structure L1”, it is the Contractor’s risk to manage and mitigate. Therefore, the finish date will not be impacted.

A strong project schedule is essential to effective project management, mitigating risks, ensuring accountability, and fostering transparent communication between all parties involved.

What is Concurrency in Most Contracts?

Concurrency occurs when two or more delay events, one caused by the employer and one by the contractor, overlap in time and impact the project's completion. These delays run simultaneously and create a complex situation regarding the responsibility for the delay and the entitlement to an Extension Of Time (EOT) or other compensatory relief.

Let’s consider an example from an office building project:

Suppose there is a delay caused by the contractor due to the late delivery of structural steel, while, at the same time, the employer issues a significant design change that further delays the project. Both of these delays overlap, causing what is known as a concurrent delay.

In most construction contracts, when delays from both parties occur concurrently, it is generally accepted that the contractor is responsible for mitigating and recovering from these delays. This might involve resequencing the work, accelerating tasks, or adjusting resources. During full concurrency, the contractor is usually not entitled to an EOT. The rationale is that both the employer's delay and the contractor's delay offset each other during the concurrent period.

However, the situation changes once the employer's delay exceeds the contractor's delay. When the employer’s delay lasts longer than the contractor’s delay, the contractor becomes entitled to an EOT for the duration of the employer's delay that exceeds the contractor's delay.

Example:

Returning to the office building project example, let’s say the contractor experiences a delay of 5 days due to the late delivery of steel, while the employer’s design change causes a delay of 12 days. During the first 5 days, the delays are concurrent, so the contractor is not entitled to an EOT for that period.

However, once the contractor's delay has run its course (after five days), the remaining seven days of the employer’s delay become the contractor's entitlement to an EOT, as the employer's delay is now the sole cause of the extended delay.

Thus, the contractor can apply for an EOT of 7 days (12 days of employer delay minus 5 days of contractor delay). While the contractor still bears responsibility for the initial delay, they will be protected from the employer-caused delay for the remaining period, ensuring that they are not penalised for delays beyond their contracted obligations. 

This principle highlights the importance of clearly distinguishing between full concurrency (where delays from both parties overlap completely) and partial concurrency (where the employer's delay extends beyond the contractor's delay). In the latter case, the contractor’s entitlement to an EOT arises as soon as the employer's delay extends beyond the contractor's own delay.

For concurrent delays, contracts often require the contractor to focus on mitigation and recovery strategies, but also protect the contractor’s rights by acknowledging any employer-caused delays that extend beyond their own. This helps ensure that the project’s timeline remains fair and equitable.

Managing Changes in a Project Program

Regularly and accurately updating the project schedule is crucial for the success of any construction project. It ensures that progress is tracked effectively and any potential issues are identified early, allowing for timely corrective actions. Equally important is maintaining a comprehensive record of all program changes, including delays, variations, and other disruptions.

When delays occur, having accurate and detailed records becomes the foundation for a reliable delay analysis. These records help project teams model the delays and their impact on the critical path, enabling a thorough understanding of the root causes. Accurate documentation is also essential for identifying concurrent delays and ensuring compliance with contract requirements, which can lead to a smoother resolution process and fewer disputes between contractors and employers.

Ultimately, keeping up-to-date records and maintaining a disciplined approach to schedule management helps project teams stay on track, reduce risks, and deliver successful outcomes, even in the face of delays.

Conclusion

Accurate and regular updates to the project schedule are essential for managing construction projects effectively, as they help identify potential risks early and maintain project momentum. Equally important is maintaining a comprehensive record of all program changes, such as delays, variations, and acceleration requests. These records form the backbone of any reliable delay analysis.

When delays occur, accurate and well-maintained records allow for precise modelling and analysis of their impact on the critical path. This not only ensures compliance with contractual requirements but also helps identify concurrent delays, allowing for fair and objective dispute resolution. By using tools like Gantt charts and modern scheduling software, project managers can visually track progress and changes, ensuring clear communication among stakeholders and reducing the risk of disputes.

Ultimately, mastering delay analysis helps contractors and employers navigate delays more efficiently, mitigate risks, and maintain project schedules, even when challenges arise.