Schedule Compression: Crashing vs. Fast Tracking for Exam

PMBOK v8 Definition

Schedule compression is a technique used to shorten the schedule duration without reducing the project scope. Schedule compression techniques are used to meet schedule constraints, imposed dates, or other schedule objectives. A helpful technique is the negative float analysis.

Two primary schedule compression techniques exist:

• Crashing: A schedule compression technique used to shorten the schedule duration for the least incremental cost by adding resources.
• Fast tracking: A schedule compression technique in which activities or phases normally done in sequence are performed in parallel for at least a portion of their duration.

Why It Matters for the Exam

Schedule compression questions appear frequently in PMI exams, particularly in the Planning and Monitoring & Controlling process groups. The exam tests your ability to distinguish between crashing and fast tracking, identify when each technique is appropriate, and recognize their respective risks and trade-offs. Expect scenario-based questions where you must select the correct technique based on cost, risk, or schedule constraints.

Key Points to Remember (for the exam)

• Crashing Definition: Shortens schedule duration for the least incremental cost by adding resources. Examples include approving overtime, bringing in additional resources, or paying to expedite delivery.
• Crashing Constraint: Works only for activities on the critical path where additional resources will shorten the activity's duration.
• Crashing Risks: Does not always produce a viable alternative and may result in increased risk and/or cost.
• Fast Tracking Definition: Activities or phases normally done in sequence are performed in parallel for at least a portion of their duration.
• Fast Tracking Example: Constructing the foundation of a building before completing all of the architectural drawings.
• Fast Tracking Risks: May result in rework and increased risk. Fast tracking only works when activities can be overlapped to shorten the project duration on the critical path.
• Common Confusion: Crashing adds resources (cost increase), fast tracking overlaps activities (risk increase). Both are used when the critical path has negative float.

Typical PMI Exam Example

Your project has a critical path duration of 12 months, but the customer requires completion in 10 months. The project sponsor approves overtime pay for the critical path team members. This is an example of crashing, because you are adding resources (overtime) to shorten the schedule duration for the least incremental cost.

PMI Exam Traps

• Trap: Confusing crashing with fast tracking

• Reality: Crashing adds resources (cost-focused), fast tracking overlaps activities (risk-focused)

• Trap: Thinking crashing works on any project activity

• Reality: Crashing works only for activities on the critical path where additional resources will shorten the activity's duration

• Trap: Believing fast tracking has no cost impact

• Reality: Fast tracking may result in rework and increased risk, which can lead to cost increases

• Trap: Assuming schedule compression reduces project scope

• Reality: Schedule compression techniques are used to shorten the schedule duration without reducing the project scope

Important PMI Connections

Quick Review Questions

1. A project manager needs to shorten the project duration by 3 weeks. The team decides to pay for expedited delivery of materials on the critical path. Which schedule compression technique is being used?

2. Your project is behind schedule, and you decide to start testing activities before all development is complete. What schedule compression technique are you applying, and what is the primary risk?

3. A sponsor asks you to shorten the project duration without increasing costs. Can you use crashing? Why or why not?

4. The critical path has negative float of -2 weeks. What does this indicate, and which schedule compression technique would you consider first if cost is the primary constraint?

5. Fast tracking and crashing both aim to shorten schedule duration. What is the fundamental difference in how each technique achieves this goal?

PMBOK v8 Reference

Section 5.20 - Schedule Compression (Figure 5-20: Schedule Compression Comparison)