Project Schedule Classification System
Context
In construction project management, while scope and cost often receive significant attention, the project schedule is equally critical in determining a project's success. Yet, scheduling can sometimes be undervalued, leading to costly delays and client dissatisfaction. This article advocates for effective schedule planning and classification throughout a project’s lifecycle. It explores the various levels of project schedules, the critical path methodology (CPM), and best practices for schedule development. By understanding the role of scheduling and its impact on the overall project, construction managers can enhance coordination, improve timelines, and better meet client expectations.
The Degree of Definition for Scope, Cost, and Schedule
As a project idea matures, more information becomes available, and specifications become clarified. The idea gradually moves from concept to product with the support of Architects and engineers. They usually label their drawings following the 30-60-90 issued for construction (IFC) approach, with each number representing a progress percentage to complete project definition—schematic design, design development, and construction documents.
If we look at another primary project objective, the budget, it follows a similar classification. Recognized in the construction industry, there are five classes of cost estimates: Class 1, Class 2, Class 3, Class 4, and Class 5, as defined by ASTM E2516. In Canada, it is common to see Class A, Class B, Class C, and Class D. These classes are based on the project's level of definition.
But what about the third primary project objective—the schedule? The schedule often receives less attention compared to project scope and budget. However, one of the major client dissatisfactions relates to delayed projects and their associated costs. Planning and execution for success are required. When construction managers, such as Xenofan Consultants, offer preconstruction expertise, they focus not only on effective coordination and planning but also on critical aspects like Cost estimation, schedule constructability reviews, and schedule development. There are also five classes of project schedules.
Project Schedule Classification System
Drawings, cost estimates, and schedules are communication tools that provide project stakeholders with essential information. AACE Recommended Practice No. 37R-06 defines five schedule levels:
Level 0: A single bar spanning from project start to finish, indicating the major milestones throughout the key project scope.
Level 1: The project is represented by its major components, with each component including its key milestones. This is a primary bar chart, with multiple bars or multiple Level 0 schedules on the same graph.
Level 2: Each major project component is further subdivided into work packages—smaller and more manageable components. The same approach is applied, with a bar showing a component's start and finish and its key milestones.
Level 3: At this level, each work package is subdivided into activities required to complete them. This is the first level where critical path methodology (CPM) can be effectively and efficiently used for monitoring and controlling project duration.
Level 4: At this point, the schedule can be further developed or refined, depending on how the concept of activity is defined.
Delays Analysis and CPM Methodology
Delays in construction projects may result from contractor or subcontractor failures, neutral events, or owner-related issues. The contractor is entitled to a time extension for neutral events and both a time extension and compensation for owner-caused delays. However, if the delay is due to the contractor's shortcomings, they must find ways to accelerate the schedule to get back on track or risk liquidated damages.
It is in the best interest of all parties to have at least a Level 3 schedule developed before project kick-off. Level 3 relies on the critical path methodology (CPM), where the critical path is the longest sequence of tasks that dictates the overall project duration. Any delay to an activity on the critical path will delay the entire project. In the case of disputes, courts often prefer delay analyses based on CPM or network scheduling. Various software tools like MS Project and Primavera assist in planning, developing, and managing schedules in complex projects.
Schedule Planning vs. Schedule Development
The schedule management plan, sometimes referred to as schedule design, is part of the execution strategy, providing a framework for planning, developing, and managing the project schedule. Schedule planning and schedule development are two distinct but interrelated activities. Schedule planning typically comes first, identifying and documenting the relationships between project activities to create a network diagram. This stage does not account for resource availability.
Schedule development, as defined by the PMBOK, is “the process of analyzing activity sequences, durations, resource requirements, and schedule constraints to create the project schedule model for project execution, monitoring, and controlling.” This means that schedule development is a resource-driven iterative process aimed at optimizing project sequencing and creating a baseline schedule for the project.
Schedule Communications
The project schedule itself is a communication tool. In practice, one might question the value of sending a six-page Level 4 project schedule to the owner. What is the intent or purpose of providing such detailed information? Perhaps only a specific portion of a Level 4 schedule would be useful to a subcontractor. Schedules should be communicated based on the information needs of each stakeholder. Sometimes, owners simply want to see a summarized Level 1 schedule baseline and progress updates for a high-level overview.
Now, do we share source files, such as .mpp (Microsoft Project) files, with clients and project stakeholders? This issue is probably similar to past ones related to sharing .dwg (AutoCAD) files or today's sharing of Building Information Modeling (BIM) files. Ultimately, it is important to accommodate stakeholders' information needs that can improve project efficiency and transparency.
Take aways
The integration of scope, cost, and schedule management is crucial to the successful delivery of construction projects. While much emphasis is often placed on scope definition and budget alignment, schedule development and classification must not be overlooked. A well-structured project schedule, particularly when developed to at least Level 3, allows for detailed activity breakdowns and the use of critical path methodology (CPM) to monitor project timelines effectively. Each level of schedule—from high-level milestones (Level 0) to more detailed activity sequencing (Level 4)—serves specific communication needs for different stakeholders. By employing these structured levels of scheduling, construction managers can mitigate risks, minimize delays, and improve overall project efficiency. Ultimately, a balanced focus on all three primary project objectives leads to better project outcomes and increased client satisfaction.
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Reference
ASTM E2516-11. Standard Classification for Cost Estimate Classification Systems. ASTM International, 2011.
AACE RP 37R-06. Schedule Levels of Detail as Applied in Engineering, Procurement, and Construction. AACE International, 2006.
Revay, Steve. "Delay Analysis Revisited." The Revay Report, Vol. 13, No. 2, June 1994. Revay and Associates Limited.
PMI (Project Management Institute). A Guide to the Project Management Body of Knowledge (PMBOK® Guide), 6th ed. Newtown Square, PA: Project Management Institute, 2017.
AACE. "A Framework for Schedule Design: Planning for Schedule Development." Presented at the AACE 52nd Annual Meeting & ICEC 6th World Congress, June 2008.