There are different schedule life cycle types (often called project life cycle). The project manager will choose the best that suits the project requirements. The life cycles are explained below:

Predictive: The entire work is planned and scheduled in the beginning of the project.


Iterative/agile: One or more specific task is planned to be done in periods (iterations) e.g. Three one-week periods. When done, another activity is planned/worked on. This cycle continues.


Adaptive: Same as iterative/agile. However, work is planned in many more and smaller iterations. Hence, there are frequent outcomes coming out from iterations. Adaptive is used in complicated/complex projects.


Rolling Wave Planning: It is iterative planning in which near term work is planned in detail, while the work in future is also planned but at a lower level of detail.


Incremental: Portion of entire work is planned and completed. Then next portion of entire work is planned/completed and this cycle continues.


Hybrid: A combination of approaches for different projects or sub-projects.

Scheduling methodology is set of rules and methods used to develop schedule. Various scheduling methodologies that exists include:

  • Critical Path Method (CPM): Schedule is created by looking at activity duration and activity relationship.

  • Critical Chain Method: It is CPM, with effect of assigning resources to activities.

  • Location-based scheduling (LBS): It develops a schedule that shows:

    • Location and time of the activity,
    • Movement of the crews through time and location.
    • LBS focuses on optimizing resource utilization and their production rates.
    • LBS is also known as vertical production method, linear scheduling, repetitive scheduling method, flow production and flow-line scheduling.

  • On-Demand Scheduling:

    • Activities are defined with duration and dependencies. 
    • Each activity is pulled for execution when the resource is available. 
    • The purpose of on-demand scheduling is to limit a team's work-in-progress (WIP) in order to balance the demand against a team's delivery throughput. 
      It is usually used in adaptive life cycle.

  • Lean Scheduling:

    • It is same as On-Demand Scheduling, with focus on minimizing waste (lags, delays, extra time) in order to maximize value. The project team collaborates in pull planning sessions and performs these steps:

      • Master scheduling:  Identifies key milestones, key activities, and phases. 
      • Phase scheduling. Identifies phases from master schedule:

        • Determines duration, sequences, constraints for each phase.
        • Phase schedule is used to generate look-ahead schedules (work to be done in next periods)

      • Look-ahead planning: By considering resource capacity, detailed plans for work to be done in next weeks are established.

  • Intelligent Systems:

    In software, assumptions and activity requirements, such as constraints, hard logic (mandatory dependency), resources, and conditions (IF-THEN-ELSE) are entered.
    Schedule model learns from progress made and proposes a new sequence of relationships for remaining work. Another option is that the software learns from other projects’ schedule models and based on that, it reserves materials, equipment and workers.

  • Line of balance:

    It focuses on production rates over time for repetitive activities. The main objective is to find the required resources for each activity. It calculates productivity along with time in an easy graphical representation.

What is performance threshold? Performance thresholds are conditions of activities. Once these conditions are met, further analysis and action is required.

Performance threshold examples:

Finish date variance threshold of -2:  It means activity can finish 2 days later than its planned finish date. If as per current status, it is finishing more than 2 days late, an action is required to prevent it from delaying further or to fast-track or crash activity to bring make it finish earlier.

Start date variance threshold of -1:   It means activity can start 1 day later than its start date.

Other thresholds could be set for SPI, CPI, Total Float, Free Float.  The schedule analyst, after discussing with stakeholders decide performance thresholds to use and their limits to set.

The schedule model development approach includes tasks such as:

Selecting data for:

  • Creating activities
  • Resources
  • Calendars
  • Work Breakdown Structure (WBS)
  • Milestones
  • Lags
  • Dependencies
  • Activity duration

This data can be gathered in team meetings, BoQs (Bill of quantity), etc.  

Further, we also choose:

  • Schedule model presentation forms e.g. Gantt Chart, table, milestones, network diagram, simple list.
  • Schedule life cycle type. Schedule Life cycles are explained here.

Various sources can be referred to for help when defining schedule development approach, explained here.

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