Develop Schedule 

Developing schedule process begins with planning schedule management, where guidelines, tools, and level of detail are defined. Next, project activities are identified and sequenced, establishing logical relationships such as dependencies (finish-to-start, start-to-start, etc.). This is followed by estimating activity durations, considering resource availability, productivity, and uncertainty.

Once durations are estimated, the schedule is developed using techniques such as network diagrams, critical path method (CPM), or iterative approaches in Agile environments. This step determines the overall project timeline, identifies the critical path, and highlights schedule flexibility (float/slack). Resource optimization and schedule compression techniques like crashing or fast tracking may also be applied to meet deadlines.

The schedule is then baselined, forming a reference point for performance measurement. Finally, throughout the project, the schedule is monitored and controlled, ensuring progress aligns with the plan and enabling timely corrective actions.

Schedule development is iterative, adaptable, and closely aligned with value delivery and stakeholder needs.

Step#1 Define activities by Decomposing the Work Packages into Activities

• The Work packages, which are the lowest level in the Work Breakdown Structure (WBS) are decomposed into activities, to form the activity lists.

• The activities are then sequenced based on their dependencies to arrive at the activity sequences.

• These activity lists are then integrated to form the schedule network diagram 

Step#2 Determine sequence with the help of Schedule Network Diagrams 

• • There are two types of schedule network diagrams;

    • Activity On Arrow (AOA) diagrams where activities are represented as arrows and are connected at nodes. Activity on Arrow diagrams are also known as Arrow Diagramming Method (ADM). ADM can show only Finish to Start (FS) dependencies, hence not widely used. 

    • Activity On Node (AON) diagrams, which are also known as Precedence Diagramming Method (PDM) represents activities on the nodes and are connected by arrows. AON can represent all the four types of dependencies like Finish to Start (FS), Finish to Finish (FF), Start to Start (SS) and Start to Finish (SF). 

Step#3 Estimate effort and duration 

Activity Duration Estimation is the process of predicting the number of time periods required to complete each project activity using available resources. It is a key step in schedule development, as it directly influences the overall project timeline.

Common techniques:

• Expert Judgment: Using experience of knowledgeable individuals

  • •   Delphi technique 

      • Planning poker (Discussed in detail in Agile section)

• Analogous Estimating: Based on durations of similar past projects

• Parametric Estimating: Using statistical relationships (e.g., units per hour)

• Three-Point Estimating: Uses Optimistic (O), Most Likely (M), and Pessimistic (P) values to calculate expected duration

• Bottom-Up Estimating: Estimating at detailed activity level and aggregating

• Story points (Discussed in detail in Agile section)

• T-shirt sizing

Reserve Analysis 

Reserve analysis in scheduling is a technique used to determine the amount of buffer (time reserves) required in a project schedule to address uncertainty and risks. In any project, activity durations are subject to variability due to unknowns. Reserve analysis helps the project manager add time contingencies to improve the reliability of the schedule.

Types of reserves:

Contingency Reserve: Added for identified risks (known-unknowns). It is included within the schedule baseline and is allocated to specific activities or phases.

Management Reserve: Set aside for unforeseen risks (unknown-unknowns). It is not part of the schedule baseline but is controlled by management and used when needed.

Step#4  Adjust by performing Schedule Network Analysis 

• Once the schedule network diagrams are ready, schedule network analysis is performed.

  • Forward pass to calculate the Early Start (ES) and the Early Finish (EF)

  • Backward pass to calculate the Late Start (LS) and the Late Finish (LF)

  • Float is calculated 

    • Float which also called Slack is the amount of time an activity can be delayed without affecting the project end date. 

      • LS - ES 

      • LF - EF 

Critical Path

• • Critical path - Is the longest path in the network, or the shortest possible time in which the project can be completed.

  • Activties on the critical path will have zero float, In other words, we arrive at the critical path by connecting all actvities whose float or slack = 0. 

  • Activities on the critical path should not slip. If they slip by 1 day, the project will slip by 1 day.

  • It is quite possible for a project to have multiple critical paths (which have the same duration and is the longest)

  • Within the project network, there can be paths with very less float. Hence they are very close to the critical path. Such paths are known as Near Critical Paths. 

  • Critical path can change during project execution. In other words, they are dynamic in nature, hence must be monitored and controlled regularly. 

  • Schedule networks are continuously optimized by;

    • • Fast tracking - Trying to do things in parellel, which were originally scheduled sequentially

      • Crashing - Trying to compress the duration of an activity by adding more resources to it. The additional concepts to be understood about crashing are;

        • • Crash duration is always lower than the Normal duration 

          • Crash cost is always higher than the Normal Cost 

      • Schedule optimization or catchup is achieved by doing both fasttracking and crashing activities on the critical path. 

Law Of Diminishing Returns 

Law of diminishing returns. When one factor (e.g., a resource) used to determine the effort required to produce a unit of work is increased while all other factors remainfixed, a point will eventually be reached at which additions of that one factor start toyield progressively smaller or diminishing increases in output

Leads & Lags 

Leads and lags are scheduling concepts used to fine-tune the timing of activities by adjusting the relationship between dependent tasks.

Lead - A lead allows a successor activity to start before its predecessor is fully completed. It represents an overlap between activities and helps to shorten the schedule.

Example:

In construction, interior painting may start 2 days before plastering is fully completed.

This is a lead of 2 days.

Lag - A lag introduces a delay between two dependent activities, meaning the successor starts after a certain time gap once the predecessor is completed.

Example:

After pouring concrete, you may need to wait 7 days for curing before starting the next task.

This is a lag of 7 days.

Resource leveling 

Resource leveling is a schedule optimization technique used to adjust the project schedule based on resource constraints. It ensures that resources (people, equipment, materials) are not over-allocated or used beyond their capacity. In many projects, certain resources may be assigned to multiple activities at the same time, causing overallocation. Resource leveling resolves this by delaying or extending activities until the required resources are available. As a result, the project schedule may change, and the project duration can increase.

Critical Chain 

Instead of identifying only the longest path of activities (critical path), CCM identifies the critical chain—the sequence of tasks that determines the project duration after accounting for both dependencies and resource limitations.

Key features:

Resource dependency considered - Activities are scheduled based on resource availability, not just logical sequence.

Buffers instead of safety margins in tasks - Individual task safety times are removed and consolidated into buffers.

Rolling wave Planning (Moving window)

Rolling Wave Planning is an iterative planning technique used in project schedule development where near-term work is planned in detail, while future work is planned at a higher level. As the project progresses, upcoming activities are progressively elaborated into more detailed plans.