Until recently it was unmistakably the Critical Path Method (CPM) and Waterfall (phase-wise compartmentalized approach) that was the most preferred construction scheduling approach. This trend is changing due to the rapid changes happening around the project enterprise.

The first and foremost change is the redefinition of a project’s success criteria. The new success criteria emphasize the achievement of the project’s business goals apart from the triple constraints of time, cost and scope. This forces project teams to deliver value faster, rather than blindly sticking to time, cost and scope as the sole criteria.

Another change is connected with the project’s changed environment where co-located teams are replaced by distributed teams, with team members working from home and a growing preference for gig workers over permanent employees. This has resulted in a wider adoption of Scrum (the most popular among the agile family of frameworks) best practices like shorter planning cycles, daily team meetings, transparent progress monitoring etc, due to their relevance to succeed in today’s distributed and concurrent work environments.

These changes are complemented by occurrences like the Project Management Institute (PMI) leading the way with Hybrid project management (merging predictive and agile methods), and other bodies like AACE, PRINCE2 following the trend.

In a nutshell, project life cycles and scheduling approaches have changed across all domains of project management, including EPC projects. This post explores this phenomenon further and ends by offering a conclusion about which is the best project life cycle and scheduling approach for construction / EPC projects.   

The best-known project life cycles

• Predictive life cycle – Predictive life cycles are appropriate when the degree of change is low and the frequency of delivery is also low. Predictive life cycles are also known as The Waterfall. In predictive life cycles, the phases of the project are well compartmentalized. For example: scope definition, high level design, detailed design, construction, commissioning, and hand over. The end of each phase is highlighted by a formal closure of the phase and a formal handover to the subsequent phase. This was and continues to be the predominant style in EPC projects.

• Iterative life cycle – Iterative life cycles are ideal when the degree of change is high, and the frequency of delivery is low. You start with a proof of concept and iterate it further by soliciting and incorporating feedback, and you do this until it reaches a satisfactory level of detailing. This approach is primarily used in the architecture phase where one start with a rough sketch and then elaborate the details further through iterations.

• Incremental life cycle – This is ideal when the frequency of delivery is high, and the degree of change is low. In this model, the team designs, builds, reviews, and transfers artifacts incrementally. For example, during the engineering phase of EPC projects, engineering drawings are completed and sent for approval on a continuous basis.

• Adaptive life cycle – This is suitable when the degree of change and frequency of delivery are both high. A combination of iterative and incremental is widely used in information technology products where the product is incremented in iterations, which is the backbone of all agile frameworks. This is getting adopted by concurrent engineering teams working remotely. 

• Hybrid life cycle – This is a combination of predictive and adaptive. Some phases of the project may follow adaptive, while others may follow predictive life cycles. For example, in construction projects, up until the completion of engineering work adaptive models are the right fit whereas during the construction phase the predictive life cycle is ideal as the frequency of delivery is low and the rate of change is low and difficult.

Scheduling Approaches

• Critical path method (CPM) – also known as the Precedence Diagramming Method (PDM), this is the most widely used approach used to create the schedule model. In the PDM, activities are represented as nodes and connected by arrows.
  • Critical chain can be used within the CPM. Critical chain project management is advocated by Goldratt. The critical chain starts with a CPM schedule model but differs with CPM on the following points.
    • Critical chain assumes that risks that were unforeseen will materialize during a project.
    • The focus is on the critical chain of resources and buffer management
    • Instead
    • In critical chain, activities are scheduled without buffers and buffer of buffers is created at the end of paths. This helps to accelerate projects, by only using buffers when only really required.
  • Rolling Wave Planning or Moving Window Planning is also used within CPM. A milestone-level schedule is prepared for the complete duration of the project but the detailed activity level schedules are prepared only for the immediate window of work. As the project progresses, the schedule gets decomposed further.
    
• Integrated Master Scheduling (IMS) – Interdependencies of schedules of various stakeholders and sub-projects are integrated into IMS

• Adaptive / Agile scheduling – Helps the project teams adapt to changes quickly. The central theme of all adaptive styles is the iteration. The total lifecycle of the project is broken down into smaller iterations. Iterations are planned in detail, just before starting that iteration.

• Location based scheduling (LBS) – Developed to help project managers in the construction industry with workflows and planning. LBS is also known as Vertical Production Method, with linear scheduling, repetitive scheduling method, even flow production and flowline scheduling. The LBS scheduling approach develops a schedule which shows the location and time of an event.

• On demand scheduling – Used in adaptive environments, this method is based on pull-based scheduling concepts. The purpose is to limit the team’s work in progress.

• Lean Scheduling – Based on theprinciples of lean project delivery. The project teams collaborate in pull planning sessions where the key activities, durations and hand offs between trades to complete milestones are defined. The key steps of lean scheduling are:
  • Master scheduling
  • Phase scheduling
  • Look ahead planning

• Line of Balance (LOB) – Line of balance (LOB) is a management control process used in construction where the project contains blocks of repetitive work activities, such as roads, pipelines, tunnels, railways and high-rise buildings. LOB collects, measures and presents information relating to time, cost and completion, and presents it against a specific plan.

• Building Information Modelling (BIM) – Integrating the project’s 3D design model and the schedule model allows the identification of work sequences for the design objects. Time is considered as the fourth dimension among the other dimensions such as height, width, depth.

Mapping of Scheduling approaches and project life cycle

From the mapping table above;

• Most of the scheduling approaches find a place holder in the hybrid project management, as parts of the project are more aligned to predictive project management whereas others are more aligned towards to adaptive, iterative, and incremental.
• While critical path method is the most preferred in the predictive segment, other approaches like the rolling wave planning, integrated master scheduling, location-based scheduling, LOB and BIMs co-exist with CPM, based on the nature of projects.
• BIM fits well for predictive, incremental and hybrid.
• Lean scheduling and rolling wave scheduling approaches suits well for all project life cycles

Based on this observation, the recommended project life cycle for EPC projects is ‘Hybrid Project management’ and the preferred construction scheduling approach is ‘Lean scheduling’.

This combination will help EPC projects to harness the best of Hybrid life cycle (combination of both predictive and adaptive approaches) to the fullest, during the execution phase of the project.