Schedule Compression Techniques: Crashing and Fast-Tracking

Schedule Compression Techniques: Crashing and Fast-Tracking - Complete Guide

Why Schedule Compression Techniques Are Important

Schedule compression techniques are critical tools in project management that help teams meet deadlines when faced with schedule constraints. As a PMI-SP (Scheduling Professional) candidate, understanding these techniques is essential because:

• Projects frequently face time pressures and deadline challenges
• Effective schedule compression can save projects from failure
• These techniques represent a core competency for scheduling professionals
• They demonstrate your ability to make strategic trade-offs between time, cost, and risk

What Are Schedule Compression Techniques?

Schedule compression refers to strategies used to shorten the project schedule duration while maintaining the original project scope. The two primary methods are:

1. Crashing: Adding resources to critical path activities to reduce their duration at an additional cost.

2. Fast-Tracking: Performing activities in parallel that would normally be done in sequence.

How Crashing Works

Crashing involves:

• Identifying critical path activities that can be shortened
• Adding resources (people, equipment, etc.) to these activities
• Calculating the cost-per-time unit saved (crash cost)
• Selecting activities with the lowest crash cost first for maximum efficiency
• Continuing until the desired schedule duration is achieved or no more crashing is possible

Key considerations for crashing:

• Always increases direct project costs
• May lead to diminishing returns (adding more resources doesn't always yield proportional time savings)
• Requires careful resource management
• May introduce quality risks if rushed

How Fast-Tracking Works

Fast-tracking involves:

• Identifying activities that can be overlapped or performed in parallel
• Restructuring the network diagram to reflect these overlaps
• Starting subsequent activities before predecessor activities are fully complete
• Monitoring closely for increased risks

Key considerations for fast-tracking:

• Typically doesn't increase direct costs
• Significantly increases risk due to dependencies between parallel activities
• Can lead to rework if problems occur in predecessor activities
• Has limits based on logical dependencies between activities
• Works best when activities are independent or have minimal overlap requirements

Comparing Crashing and Fast-Tracking

Crashing:
• Increases cost
• Maintains sequential relationships
• Lower risk than fast-tracking
• Subject to resource constraints

Fast-Tracking:
• Minimal cost impact
• Changes sequential relationships to parallel
• Higher risk of rework
• Limited by logical dependencies

How to Apply Schedule Compression in Practice

1. Analyze the network diagram to identify the critical path
2. Evaluate activities for compression potential
3. Calculate compression costs and risks for each approach
4. Apply compression strategically, focusing on activities with highest benefit-to-cost ratio
5. Re-analyze the critical path after each compression (as critical path may change)
6. Monitor and control the compressed schedule closely

Exam Tips: Answering Questions on Schedule Compression

For Multiple Choice Questions:

• Look for keywords like "lowest cost method" (likely crashing) or "highest risk method" (likely fast-tracking)
• Pay attention to whether the question focuses on cost, schedule, or risk impacts
• Remember that crashing always increases direct costs while fast-tracking generally doesn't
• Note that crashing has limits based on resources while fast-tracking has limits based on dependencies

For Calculation Questions:

• Calculate crash cost per time unit for each activity: (Crash Cost - Normal Cost) ÷ (Normal Duration - Crash Duration)
• Always crash activities with lowest cost slope first
• Remember to recalculate the critical path after each activity is crashed
• Watch for questions with resource constraints that limit crashing options

For Scenario-Based Questions:

• Identify whether time, cost, or risk is the primary constraint
• If time is most critical with budget flexibility, crashing may be preferred
• If budget is tight but schedule must be reduced, fast-tracking may be preferred
• If both time and cost are constrained, a combination approach may be necessary

Common Exam Traps:

• Assuming fast-tracking has no cost impact (it may have indirect costs from risk and coordination)
• Forgetting that crashing non-critical activities may not reduce overall duration
• Missing that after crashing activities, the critical path may change
• Not recognizing that both techniques have practical limits

Final Exam Preparation Tips

• Practice drawing network diagrams and identifying compression opportunities
• Work through sample calculations for crashing costs
• Memorize the key differences between crashing and fast-tracking
• Study real-world examples where these techniques were applied
• Review how these techniques integrate with other knowledge areas (cost, risk, etc.)

By mastering schedule compression techniques, you'll demonstrate your ability to handle one of the most challenging aspects of project scheduling: adapting to time constraints while managing costs and risks effectively.