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Sequencing and Scheduling

Sequencing and scheduling are key activities in project management that involve determining the order of tasks and defining their start and end dates to ensure that the project is completed on time and within scope.

Sequencing Activities:

  1. Identify Dependencies:
    • Finish-to-Start (FS): The predecessor task must finish before the successor task can start.
    • Start-to-Start (SS): The predecessor task must start before the successor task can start.
    • Finish-to-Finish (FF): The predecessor task must finish before the successor task can finish.
    • Start-to-Finish (SF): The predecessor task must start before the successor task can finish.
  2. Create the Task List:
    • Compile a comprehensive list of all project tasks, ensuring each task is clearly defined.
  3. Determine Task Durations:
    • Estimate the time required to complete each task based on historical data, expert judgment, and other estimation techniques.
  4. Identify Constraints:
    • Consider any constraints that may affect task sequencing, such as resource availability, external dependencies, or regulatory requirements.
  5. Develop the Sequence:
    • Arrange tasks in a logical order, taking into account dependencies and constraints, to form a coherent workflow.

Scheduling Activities:

  1. Define Milestones:
    • Identify key project milestones and set target dates for their completion.
  2. Assign Resources:
    • Allocate resources to tasks based on their availability and skill sets.
  3. Create the Schedule:
    • Develop a detailed project schedule using scheduling tools and techniques, such as Gantt charts or network diagrams.
  4. Optimize the Schedule:
    • Review the schedule for any potential bottlenecks or inefficiencies and make adjustments as necessary.
  5. Baseline the Schedule:
    • Establish a baseline schedule to serve as a reference point for monitoring and controlling project progress.
  6. Monitor and Update:
    • Continuously monitor the schedule against actual progress and update it to reflect any changes or deviations.

Network Planning Models

Network planning models are used to represent the sequence of activities in a project and to identify the most efficient path to complete the project. These models help in visualizing task dependencies, estimating project duration, and identifying critical tasks.

Key Network Planning Models:

  1. Critical Path Method (CPM):
    • Purpose: Identify the longest path of dependent activities (critical path) that determines the project duration.
    • Steps:
      1. List all tasks required to complete the project.
      2. Determine dependencies between tasks.
      3. Estimate the duration of each task.
      4. Draw a network diagram.
      5. Calculate the earliest and latest start and finish times for each task.
      6. Identify the critical path.
  2. Program Evaluation and Review Technique (PERT):
    • Purpose: Estimate project duration by considering uncertainty in task durations using three-time estimates (optimistic, most likely, pessimistic).
    • Steps:
      1. Define tasks and dependencies.
      2. Estimate three-time durations for each task.
      3. Calculate the expected duration for each task.
      4. Draw the network diagram.
      5. Identify the critical path.
  3. Precedence Diagramming Method (PDM):
    • Purpose: Represent project activities in a network diagram using nodes and arrows to show dependencies.
    • Steps:
      1. Identify tasks and dependencies.
      2. Create nodes for each task and connect them with arrows indicating dependencies.
      3. Use different types of dependencies (FS, SS, FF, SF) to accurately represent the sequence.

Formulating Network Model

Formulating a network model involves creating a visual representation of the project’s activities, showing their dependencies, and calculating critical project metrics like the critical path.

Steps to Formulate a Network Model:

  1. List Activities:
    • Create a list of all project activities with their respective durations and dependencies.
  2. Define Dependencies:
    • Identify and document the relationships between activities (e.g., which tasks must precede or follow others).
  3. Create Nodes and Arrows:
    • Represent each activity as a node in a network diagram.
    • Draw arrows between nodes to indicate the sequence of activities and their dependencies.
  4. Assign Durations:
    • Allocate the estimated duration to each activity.
  5. Calculate Earliest Start (ES) and Finish (EF) Times:
    • Begin at the start node and calculate the earliest times by adding the duration of each activity as you move through the network.
  6. Calculate Latest Start (LS) and Finish (LF) Times:
    • Begin at the end node and work backward, subtracting the duration to determine the latest times that activities can start and finish without delaying the project.
  7. Determine the Critical Path:
    • Identify the path with the longest duration through the network, which determines the minimum project completion time.
    • Activities on the critical path have zero slack (float) and are critical to project timing.
  8. Identify Slack Time:
    • Calculate slack time for each activity, which is the difference between the earliest and latest start times (or finish times).
    • Slack time indicates the flexibility in the start or finish time of activities without affecting the project completion date.
  9. Review and Validate:
    • Ensure that the network model accurately represents the project activities and their dependencies.
    • Validate the model with project stakeholders to confirm accuracy and completeness.

Example of Network Model Formulation:

  1. List of Activities and Durations:
    • A: 3 days
    • B: 2 days
    • C: 4 days
    • D: 2 days
  2. Dependencies:
    • A must finish before B and C can start.
    • B must finish before D can start.
    • C and D are the final tasks.
  3. Network Diagram:

scss

[A]---(3 days)---[B]---(2 days)---[D]---(2 days)

| |

+---(4 days)---[C]

  1. Critical Path Calculation:
    • ES and EF:
      • A: ES = 0, EF = 3
      • B: ES = 3, EF = 5
      • C: ES = 3, EF = 7
      • D: ES = 5, EF = 7
    • LS and LF:
      • A: LS = 0, LF = 3
      • B: LS = 3, LF = 5
      • C: LS = 3, LF = 7
      • D: LS = 5, LF = 7
    • Critical Path: A -> B -> D (Total Duration = 7 days)

Sequencing and scheduling, network planning models, and formulating network models are fundamental components of effective project management. These techniques help in creating a structured approach to managing project tasks, optimizing resource allocation, and ensuring timely project completion. Utilizing methods like CPM, PERT, and PDM enables project managers to visualize task dependencies, identify critical paths, and mitigate potential risks, thereby enhancing the likelihood of project success.