Planning & Managing Schedule

Schedule management is about getting the project done on time. It involves defining activities, sequencing them, estimating durations, and developing a schedule that meets project objectives.

Schedule Management Processes

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Defining Activities

Activity Definition is the process of identifying and documenting the specific actions to be performed to produce the project deliverables.

Activity vs. Work Package

Activity Attributes

Each activity has attributes including:

• Activity ID and description
• Predecessor and successor activities
• Logical relationships
• Leads and lags
• Resource requirements
• Imposed dates
• Constraints and assumptions

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Sequencing Activities

Activity Sequencing determines the logical order in which activities should occur.

Precedence Diagramming Method (PDM)

PDM (also called Activity-on-Node) is the most common network diagramming technique. Activities are represented as nodes, and arrows show dependencies.

Dependency Types (Logical Relationships)

Finish-to-Start (FS) is the most commonly used relationship.

Leads and Lags

Dependency Categories

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Duration Estimation Techniques

Comparison of Estimating Techniques

Analogous Estimating

Uses historical data from similar activities or projects:

• Advantage: Quick and inexpensive
• Disadvantage: Less accurate, depends on similarity
• Best For: Early estimates when details are limited

Parametric Estimating

Uses statistical relationships between historical data and variables:

• Example: Cost per square foot x total square feet
• Example: 2 hours per requirement x 50 requirements = 100 hours
• Advantage: More accurate than analogous when good data exists
• Disadvantage: Requires valid historical data and relationships

Three-Point Estimating (PERT)

Uses three estimates to account for uncertainty:

Triangular Distribution: E = (O + M + P) / 3

Beta Distribution (PERT): E = (O + 4M + P) / 6

Standard Deviation (Beta): SD = (P - O) / 6

Bottom-Up Estimating

Estimates individual activities and aggregates them:

• Advantage: Most accurate
• Disadvantage: Time-consuming and expensive
• Best For: Detailed estimates when WBS is complete

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Critical Path Method (CPM)

The Critical Path Method identifies the longest path through the project network, determining the minimum project duration.

Key Concepts

CPM Calculations

Forward Pass (calculates Early Start and Early Finish):

• ES = Earliest an activity can start
• EF = ES + Duration

Backward Pass (calculates Late Start and Late Finish):

• LF = Latest an activity can finish
• LS = LF - Duration

Float Calculation:

• Total Float = LS - ES = LF - EF
• Activities with zero float are on the critical path

Example Network Calculation

Activity | Duration | ES | EF | LS | LF | Float | Critical?
---------|----------|----|----|----|----|-------|----------
A        | 3        | 0  | 3  | 0  | 3  | 0     | Yes
B        | 4        | 3  | 7  | 4  | 8  | 1     | No
C        | 5        | 3  | 8  | 3  | 8  | 0     | Yes
D        | 2        | 8  | 10 | 8  | 10 | 0     | Yes

Critical Path: A → C → D (Duration: 10 days)

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Schedule Compression

When the schedule must be shortened, use these techniques:

Crashing

Adding resources to critical path activities to reduce duration.

Fast-Tracking

Performing activities in parallel that were originally planned in sequence.

Comparison

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Schedule Presentation

Gantt Charts

Gantt charts display activities as horizontal bars against a calendar:

• Shows activity start and end dates
• Displays task dependencies
• Easy to understand and communicate
• Can highlight critical path activities

Milestone Charts

Show key dates and deliverables:

• High-level view for executives
• Focus on major achievements
• Simple and easy to communicate

Network Diagrams

Show activity relationships and sequences:

• Precedence Diagramming Method (PDM)
• Useful for analyzing dependencies
• Required for CPM calculations

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Resource Optimization

Resource Leveling

Adjusts the schedule based on resource constraints:

• May extend the critical path
• Resolves resource over-allocation
• Changes start and finish dates

Resource Smoothing

Adjusts activities within their float to reduce resource peaks:

• Does not extend the critical path
• Works within existing schedule constraints
• May not fully resolve over-allocation

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Key Takeaways

• Activity definition identifies actions needed to produce deliverables
• PDM uses FS, SS, FF, and SF relationships to sequence activities
• Duration estimation ranges from quick analogous to detailed bottom-up
• Critical path is the longest path and determines project duration
• Float indicates schedule flexibility for non-critical activities
• Crashing adds resources; Fast-tracking overlaps activities