4 The traditional, sequential methodologies

Learning Outcomes

  • Determine the importance of traditional project management methodologies.
  • Analyse the processes of Waterfall, Critical Path Method and Critical Chain Project Management
  • Assess the benefits and disadvantages of adopting traditional project management methodologies


Traditional or sequential project management methodologies are run in a linear fashion, following 5 common phases: initiation, planning, execution, monitoring, and closure. This process requires upfront planning, documentation, and prioritisation (Salameh 2014; Jovanovic and Beric 2018). Using this approach requires defining the scope up front and setting the project requirements at the start.

Therefore, traditional project management requires the use of a project manager or a Project Management Office that holds central responsibility over the project and is accountable for achieving outcomes (Salameh 2014; Jovanovic and Beric 2018). Once the scope has been agreed upon, and the initiation phase begins, changes must be managed through the change management process.

As these traditional project management methods rely on proper planning and analysis in the initiation phase, it is front heavy for the planning. The following process of development and design is streamlined, allowing the project manager to focus on the key tasks within the project and the project team to manage the remainder with minimal guidance. There are several tools and techniques as outlined by the Project Management Institute (PMI), including the Project Management Body of Knowledge (PMI 2017). Figure 11 shows some of the phases a traditional and sequential project may go through.

Figure 11.  Example of traditional and sequential project phases, by Carmen Reaiche and Samantha Papavasiliou, licensed under CC BY (Attribution) 4.0


Benefits of traditional project management methodology

There are several benefits of using the traditional and sequential approach, following pre-planned steps. These include (Salameh 2014; Jovanovic and Beric 2018):

  1. Clear direction. As everything is pre-planned, every project team member knows their roles and responsibilities, and follows the project requirements, allowing the project team to work efficiently and under minimum supervision.
  2. Control. The Project Management Office holds most of the power and the changes are managed by the project manager. As a result, deviations from the project scope are unlikely.
  3. Sole source of accountability. As the project manager holds the power, they are accountable for the project outcomes (either success or failure). As a result, they become the central accountability, and stakeholders know who to contact to make necessary updates.
  4. Proper documentation. This is the foundation of traditional project management methodologies. The documents are used to standardise the processes and provide guidance and support for future projects.

There are several types of traditional and sequential project management methodologies which will be discussed within this module.

Waterfall: do task A first, then task B, then task C

The most common traditional approach to project management is the Waterfall method. The method is based on completing tasks and phases in a linear manner, whereby each stage must be completed before the following begins (Kerzner 2009; PMI 2017; Lester 2021). The Waterfall method breaks down the project into several phases and tasks that are to be performed sequentially.

Common phases within Waterfall project management

Dividing a project into phases manages the project team’s focus, appropriately allocates resources, and aligns the project’s life cycle with clients and stakeholders (Kerzner 2009; PMI 2017; Lester 2021). The common phases are outlined in Figure 12. The phases may differ from project to project; however, they commonly include:

Figure 12.  Common project phases using the Waterfall method, by Carmen Reaiche and Samantha Papavasiliou, licensed under CC BY (Attribution) 4.0



1. Initiation phase

The initiation phase involves defining the new project scope or new phase of an existing project. This phase requires completing documentation to create and authorise the project, including developing the project charter, assigning the project manager, and identifying stakeholders (Kerzner 2009; PMI 2017; Lester 2021). The project charter should outline the scope statement, initiation project budget value, and primary stakeholders. Once initiated, the project manager will proceed to the planning phase.

2.  Planning

This stage involves establishing the project scope and objectives and defining how to meet objectives (Kerzner 2009; PMI 2017; Lester 2021). The primary project management plan document is created during this phase. It contains the following information:

  • Scope statement. This outlines the work that will be completed as part of the project, establishes boundaries, and considers the assumptions and constraints. A scope statement should also include what is not in scope.
  • Deliverables. What will be produced, created, or developed as part of the project need to be listed.
  • Success factors. The project success is defined, linked back to the budget and schedule required; however, additional factors around quality, stakeholder engagement, etc., should also be incorporated.
  • Schedule/timeline. The project is broken into key tasks and activities (within a work breakdown structure). Timeframes are determined for key tasks, supporting the development of the timeline and deadlines for each project deliverable and the end-to-end project.
  • Budget. This includes the estimated cost of each task and deliverable, which is collated to develop the overall project budget.
  • Human resource plan. This documents the roles and responsibilities of the project team members, and the resource acquisition processes.
  • Quality management plan. This is the development of quality requirements for each deliverable, including quality assurance and controlling processes.
  • Risk management plan. This plan identifies the potential risks, analyses their likelihood and consequence, and analyses mitigation processes and documentation within a broader plan.
  • Procurement management plan. This documents the process for acquisition and control of vendors outside the organisation.
  • Change processes. This records the methods and documentation of the change request process of the project management plan.

A project management plan needs to be distributed to the project sponsor and key decision-makers, to ensure they endorse or approve the implementation or execution of the phase (Kerzner 2009; PMI 2017; Lester 2021). Once the execution phase begins, the change control process will need to be followed for any deviations from the plan for approval.

3.  Execution/implementation

The execution/implementation phase is where the defined work from the planning phase is completed. In this phase, the project manager is responsible for work distribution, management, and assurance of the work underway (Kerzner 2009; PMI 2017; Lester 2021). The deliverables are undertaken and provided to the stakeholders for assessment. The project manager and team are responsible for:

  • Project status updates: regular updates of the status are provided to key stakeholders. As part of these status updates the project manager monitors the timelines, ensures the budget remains on track and within the schedule. Quality assurance processes should be undertaken for each deliverable.
  • Stakeholder communication and engagement: stakeholders need to be communicated with specific information and updates. This is as documented within the project management plan.

This phase is based on the steps and tasks as outlined within the project management plan, and all the steps should be working towards the project scope as outlined in initiation.

4.  Monitoring and controlling

This phase requires monitoring and controlling the process, including tracking, reviewing, and regulating and responding to the different challenges as they arise (Kerzner 2009; PMI 2017; Lester 2021). The phase is completed concurrently with the execution phase.

Within this phase the project manager needs to measure the project execution outcomes in comparison with what was planned within the project management plan. This involves reviewing the budget, and ensuring the processes are on schedule.

Many project managers use the Earned Value Analysis process to support their monitoring and controlling phase (Kerzner 2009; PMI 2017; Lester 2021). This requires calculating the schedule and cost, including several variables:

  • Planned Value (PV): budgeted amount for each task at a point of time.
  • Earned Value (EV): actual completion amount for each task compared to task budget.
  • Actual Cost (AC): actual cost for each task.
  • Cost Variance (CV): value of the cost overrun or underrun (CV = EV – AC).
  • Cost Performance Index (CPI): relative amount in which the project is over or under budget (CPI = EV / AC).
  • Schedule Variance (SV): amount the project is behind or ahead of schedule (SV = EV – PV).
  • Schedule Performance Index (SPI): relative amount the project is ahead or behind schedule (SPI = EV / PV).

Additional variables that can be analysed include:

  • Budget at Completion (BAC)
  • Estimate at Completion (EAC)
  • Variance at Completion (VAC)
  • Estimate to Complete (ETC)
  • To Complete Performance Index (TCPI).

Earned value analysis provides a snapshot of the project’s schedule and budget status at a point in time.

Where project monitoring shows changes from the project management plan, the change control process should be implemented.

5.  Closure/maintenance

The closure phase is when the project is formally closed. This is where the project manager and team determine how the project was completed (for example, was it within budget, schedule, quality parameters), and perform all the necessary due diligence to close out contracts or tasks that remain unfinished. In some instances, this phase is referred to as handing over to business as usual (Kerzner 2009; PMI 2017; Lester 2021). Within this phase, there are several key components that need to be documented within a final closure report. These include:

  • Formal closure: finalise contracts and agree that the project is completed.
  • Funding/budget: confirm final project budget and release any leftover funding.
  • Procurements: finalise vendor contracts and issue completion certificates.
  • Final details: document the work performed, and other details that need to be recorded to support future projects and provide governance as to what was completed.
  • Liabilities: clarify any warranties, insurance requirements or coverage, and bonds that either need to be established or maintained.
  • Resource release: return or release project team members, and other resources and equipment.
  • Lessons learned: document the lessons learned throughout the project to support future projects.

Benefits of Waterfall project management

There are several benefits to using Waterfall project management methods:

  • Consistent and clear documentation: documentation is created at every stage and supports a better understanding of where errors or mistakes may be made. It also makes for an easily repeated process.
  • Progress tracking is simple: using a Gantt chart (or similar) it is easy to track project progress.
  • Team members manage their time effectively: due to the level of upfront planning and documentation, stakeholders can estimate how much time each task is likely to take.
  • Simplicity: it is straightforward process that is logical and sequential in nature. Every team member is clear on what they need to be doing and when.
  • Discipline: disciplined planning, scheduling, designing, and structuring is required for all projects. Waterfall requires phasing, milestones, and deadlines.
  • Early adjustments: easy adjustments and alterations occur at the planning phase. However, it becomes difficult to make changes later in the project.

Cons of the Waterfall model

There are several cons or challenges that can arise from using Waterfall project management methods:

  • Roadblocks drastically affect timelines: due to the linearity, when a task is delayed, the entire timeline is altered.
  • Linear progress makes backtracking difficult: it is difficult to go back to a completed phase.
  • Quality assurance happens late in the project: the review stage in Waterfall occurs towards the end of the project, making it costly to fix defects.
  • Rigidity: it lacks adaptability and responsiveness.
  • Lack of user involvement: the level of client or end-user engagement is often low.

Therefore, where your project may require iteration or seeking out the best end-state, Waterfall may not be the most appropriate approach. Where a project is likely to change, requirements are unclear or testing is required throughout the project, Waterfall may not provide the best outcomes for a project.

In sum, Waterfall project management is a traditional and sequential form of project management, and the most common version within the industry according to the Project Management Body of Knowledge (PMI 2017). Waterfall requires project managers and teams to follow a linear process and sequence of activities and tasks, where they are unable to move to the next phase until the previous is completed. There are many diverse types of projects which will excel in this space, especially those which are easy to define from the start and do not require the flexibility of a cyclical approach.


Critical Path Method: string dependent tasks together from start to finish

Critical Path Method (CPM) (also referred to as critical path analysis) is used to identify and schedule the most critical tasks within a project, along with dependencies. The critical path becomes the longest sequence of critical tasks within the project. This critical path will be used to support your schedule development (Stelth and Le Roy 2009; Ahmed 2018; Nassar 2018; Atin and Lubis 2019). Within the critical path, milestones need to be documented as they are used to ensure that one task (or phase) is complete and that the project can move to the next.

How to apply critical path

There are several steps which can be followed to find the critical path and apply this method to a project (Stelth and Le Roy 2009; Ahmed 2018; Nassar 2018; Atin and Lubis 2019).

Step 1: List activities. Using a work breakdown structure, list all the project tasks and activities which need to be completed to reach the end-state. The development of this list (as outlined in Figure 13) supports the development of the next step.

Figure 13.  Work breakdown structure example, by Carmen Reaiche and Samantha Papavasiliou, licensed under CC BY (Attribution) 4.0


Step 2: Identify dependencies. Through the work completed within the work breakdown structure, consider what the dependencies are between tasks. For example:

  • Task 1B is dependent on 1A
  • Task 2A is dependent on 1A
  • Task 1C is dependent on 1B
  • Task 2B is dependent on 2A
  • Task 2C is dependent on 3A
  • Task 3C is dependent on 3B
  • Task 3C is dependent on 3C

These dependencies outline the project sequence and help determine the critical path.

Step 3: Create the network diagram. Transfer the work breakdown structure into a flowchart or network diagram which shows the linearity of activities. Each box should contain 1 task and arrows are used to outline dependencies.

Step 4: Task duration estimation. Critical path is calculated by determining the longest sequence of critical tasks. To achieve this, each task’s duration must be estimated. To help make educated estimates, use:

  • experience and knowledge
  • previous project or historical data
  • industry standards.

There are also forward and backward pass techniques which can be used in the following ways:

  • Forward pass: calculates the earliest start (ES) and earliest finish dates (EF). This uses previously stated start dates. The ES is the highest earliest finish EF dates from their closest predecessors. While EF is the ES in addition to duration (outlined in each task).
    • Within the calculation, ES is the first activity and proceeds through each task based on the estimated timeframes allocated, until you reach the EF value.
  • Backward pass: calculates the latest start (LS) and latest finish (LF) dates. The LS is calculated as the LF minus the duration, while the LF is calculated from the lowest LS value from the immediate successor task.
    • The schedule is developed by working backwards through the entire process.

These values can be used to calculate the float or allocation of scheduling flexibility which can be added to each task.

Step 5: Critical path calculation. The critical path can be calculated both manually and through an algorithm.

To calculate the critical path:

  • Document start and end times for each activity.

Activity 1 starts at 0 and the end time is the duration of the activity.

The following activity starts at the end time of the previous activity, the end date/time is the duration from the start.

Complete for each activity.

  • Identify the end time of the last activity of each sequence – this will help determine the duration of the whole sequence.
  • The activity sequence with the longest duration is the critical path. This is outlined in Figure 14.

Figure 14.  Critical Path example, by Carmen Reaiche and Samantha Papavasiliou, licensed under CC BY (Attribution) 4.0

Critical Path method example

Step 6: Float calculation. Slack or float is defined as the flexibility of a task schedule; that is, how long a task can be delayed without impacting later tasks.

Float can be used for:

  • project risks
  • unexpected issues
  • delays
  • resourcing constraints.

Floats are calculated manually. There are two types of floats (Atin and Lubis 2019):

  • Free float: how long an activity can be delayed without delaying the subsequent activity. Free float only occurs when two or more activities have the same successor. Free float equals next task ES minus current task EF.
  • Total float: amount of time an activity can be delayed without impacting the project end date. The total float equals LS minus ES or LF minus EF.

Where critical tasks have no float, they have no flexibility. Positive float tasks should not be in the critical path, as they can be delayed without affecting the project end date. Therefore, as a result, non-critical tasks can have resources reallocated from them to critical tasks.

Advantages of a CPM

The application of CPM provides several advantages, including:

  • improved future planning by comparing expected to actual progress
  • improved resource management by prioritising tasks and identifying where resources need to be
  • decreased bottlenecks by outlining the dependencies between tasks so that there is a straightforward way to view the flow in the project.

Disadvantages of CPM

There are several potential disadvantages of CPM:

  • estimating the end date of an activity can be difficult
  • the critical path can be unclear
  • networks can be complex due to the size of the project
  • resource allocation is not documented within the critical path.

How to decide whether to use CPM

CPM can be especially useful in the following circumstances:

  • for large-scale, complex projects
  • for projects with numerous dependencies
  • to support planning through visualising tasks and dependencies
  • to identify critical tasks that require attention and resourcing
  • when the project has strict deadlines.

CPM might not be appropriate when:

  • the project is simple
  • the project requires flexibility or agility
  • deadlines, timings, and duration are unclear.

In sum, the CPM is a traditional and sequential form of project management. CPM can also be used as a tool to support project planning and scheduling. Using CPM, a project manager and team can see the dependencies between tasks, the criticality of different sequences of tasks and the resource requirements. The method is used to help keep projects on track and within budget as it provides visibility.

Critical Chain Project Management: reserve resources for the most critical tasks

Critical Chain Project M anagement (CCPM) is defined as a method of project management and planning which emphasises the need for resources (including people, materials, equipment) which are needed to complete the project tasks (Leach 1999, 2000; Raz et al. 2003; Updegrove 2014). The CCPM method follows the CPM but then includes further steps. The CCPM seeks to address issues within the CPM. These issues include requiring the time duration for each task, and the duration from the beginning to the end of the project (Leach 1999, 2000; Raz et al. 2003; Updegrove 2014). Due to the requirement for estimates, some of the timeframes are unrealistic when applied.

Using CCPM allows for additional time for the human components of the project, including resourcing issues and delays (Updegrove 2014). Buffers are built into the project to account for different events happening.

The focus of this method requires the project manager to determine the critical chain. This includes the resource and activity dependencies, which inform the longest sequence of tasks (Leach 2000; Updegrove 2014). Therefore, critical project resources need to be balanced to support the critical path.

CCPM provides greater control over the project and schedules; however, it is a complex method to apply. Project teams require considerable training and capability development (Leach 1999, 2000) and this can be especially challenging when it comes to adapting to the constraint-based methodology.

Components of CCPM

There are several components of the CCPM approach (Updegrove 2014):

  • Critical path: the longest sequence of dependent tasks required to complete a project.
  • Feeding chain: the secondary chain of dependent tasks that run concurrently with the critical path.
  • Project buffers: safeguards built into the project.

There are 3 key types of buffers:

  • Resource buffers: resources set aside to support critical chain.
  • Project buffers: extra time allocated to the final task and the end of the project.
  • Feeding buffers: extra time allocated to the feeding chain.

Steps in CCPM

This process involves 7 steps (Leach 2000; Raz et al 2003; Updegrove 2014):

Step 1: Identify the critical chain. Outline critical tasks that will sequentially take the longest to complete. Figure 15 shows an example of the critical chain.

Figure 15. Critical chain example, by Carmen Reaiche and Samantha Papavasiliou, licensed under CC BY (Attribution) 4.0



Step 2: Outline resource constraints. Consider the limitations that may affect how tasks are completed.

Step 3: Specify team focus. Ensure that the project team are focused on completing their activities. This will support efficiency and collective problem-solving.

Step 4: Discourage multitasking. This can encourage project team members to focus specifically on their tasks.

Step 5: Utilise 50/50 time estimates. Decrease time estimate by 50% – this will encourage the team to be more efficient with scheduling. Buffers are still required.

Step 6: Develop buffers. Use the 50% removed in the previous step to create a buffer.

Step 7: Develop a detailed project plan. Track the project to understand how work is progressing and whether the buffers are needed, and to identify any risks.

Advantages of CCPM

Applying CCPM offers several advantages:

  • promotes concentration on work
  • encourages team morale and performance
  • decreases float mismanagement
  • outlines minimum time required to finish
  • speeds up project completion
  • reduces expenditure.

Disadvantages of CCPM

Some of the disadvantage of applying CCPM are:

  • project team dedication is required
  • if the team is not working toward a common goal, outcomes can be clouded
  • it does not support big planning requirements
  • it is new method which requires more documentation and support.

When CCPM might not be appropriate

There are instances in which CCPM might not be the best choice, including when:

  • the critical path method sounds good in theory, but more realistic measurements are required
  • overestimated task durations to document a buffer have not been clearly calculated, therefore the CCPM doesn’t support accurate data and we are unable to have accurate projections.

In sum, CCPM is a traditional and sequential project management methodology. The critical chain outlines the longest path of tasks with dependencies within a project, including the resource requirements and potential impacts on the scheduling. Therefore, the critical chain approach focuses on the schedule, which supports the different activities which are critical to the outputs, especially when delays in activities or tasks could have an impact on the end date of the project.

Test your knowledge

Key Takeaways

  • Traditional project management requires engaging a project manager or the Project Management Office to hold central responsibility over the project.
  • The Waterfall method is based on completing tasks and phases in a linear manner, whereby each stage must be completed before the following begins.
  • The CPM (also referred to as critical path analysis) is used to identify and schedule the most critical tasks within a project, along with dependencies. It’s the most used methodology for everyday project management.
  • The CCPM provides greater control over the project and schedules. However, it is a complex method to apply.


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Updegrove D (2014) The critical chain implementation handbook, Being Company, Ltd., United States.


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Management Methods for Complex Projects by Carmen Reaiche and Samantha Papavasiliou is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.