Crashing
Crashing is a project schedule compression technique used to shorten the schedule duration for the least incremental cost by adding resources. It involves analyzing activities on the critical path to determine which ones can be expedited by allocating additional resources, such as adding more staff, approving overtime, or bringing in additional equipment. The primary goal of crashing is to achieve the project’s deadline without altering the scope or compromising quality. In the context of the PMI Scheduling Professional course, understanding crashing is essential because it provides a methodical approach to schedule compression when projects are behind schedule or when the completion date is accelerated. By focusing on the critical path—the sequence of activities that dictates the project’s duration—project managers can identify the activities where accelerating delivery will have the most significant impact on the overall schedule. However, crashing is not without its drawbacks. Increasing resources can lead to higher costs, and there is often a diminishing return on investment. For example, adding more personnel to a task may lead to coordination issues, reduced efficiency, or resource overallocation. Therefore, it is crucial to conduct a cost-benefit analysis to ensure that the additional costs incurred align with the value gained from the reduced schedule duration. Moreover, crashing may introduce risks like decreased quality or increased potential for errors due to the accelerated timelines. It requires careful planning and communication with stakeholders to manage expectations and ensure that the project objectives are met without unintended consequences. In summary, crashing is a deliberate strategy to compress project schedules by adding resources to critical path activities. It requires balancing the trade-offs between cost, time, and quality, and necessitates thorough analysis and stakeholder engagement to implement effectively.
Crashing: A Comprehensive Guide for PMI-SP
Why Crashing is Important in Project Management
Crashing is a critical schedule compression technique in project management that helps teams meet deadlines when projects fall behind schedule. Understanding crashing is essential for the PMI-SP exam because:
- It demonstrates your ability to make cost-effective decisions under time constraints
- It's a fundamental technique for recovering delayed schedules
- It showcases your understanding of the relationship between project cost and duration
- It's frequently tested on PMI-SP exams as a key schedule management concept
What is Crashing?
Crashing is a schedule compression technique that involves adding resources to critical path activities to reduce their duration. The primary goal is to shorten the overall project schedule while minimizing the cost increase. It's based on the principle that for many activities, there's a trade-off between time and cost.
Key characteristics of crashing:
- Always focuses on critical path activities (since only they affect the project end date)
- Involves a cost-time trade-off analysis
- Requires additional resources (people, equipment, etc.)
- Aims for the most cost-effective schedule reduction
- Maintains the original project scope
How Crashing Works
Step 1: Identify all activities on the critical path
Step 2: Calculate the crash cost per unit time for each critical path activity
Crash Cost Per Time Unit = (Crash Cost - Normal Cost) ÷ (Normal Duration - Crash Duration)
Step 3: Select the activity with the lowest crash cost per unit time
Step 4: Crash this activity to the extent needed or possible
Step 5: Recalculate the critical path (as crashing may change which activities are on the critical path)
Step 6: Repeat the process until the desired project duration is achieved or no further crashing is economically feasible
Example:
Activity A:
- Normal: 10 days at $1,000
- Crashed: 7 days at $1,900
- Crash cost per day = ($1,900 - $1,000) ÷ (10 - 7) = $300 per day saved
Activity B:
- Normal: 8 days at $1,200
- Crashed: 6 days at $2,000
- Crash cost per day = ($2,000 - $1,200) ÷ (8 - 6) = $400 per day saved
In this case, Activity A would be crashed first as it has the lower crash cost per day.
Key Considerations When Crashing
- Diminishing returns: As you add more resources, the benefit per additional resource typically decreases
- Resource limitations: Consider the availability of skilled resources
- Quality implications: Rushing work may affect quality
- Management complexity: More resources require more coordination
- Multiple critical paths: When parallel critical paths exist, all must be crashed to reduce the schedule
Crashing vs. Fast Tracking
It's important to distinguish crashing from fast tracking:
- Crashing: Adds resources to reduce activity durations; increases cost
- Fast Tracking: Performs activities in parallel that would normally be done in sequence; increases risk but not necessarily cost
Exam Tips: Answering Questions on Crashing
1. Identify the critical path first: Questions will often include network diagrams or activity lists. Always identify the critical path before determining what to crash.
2. Calculate crash cost efficiency: Look for questions that test your ability to determine which activities provide the most schedule reduction for the least cost.
3. Watch for changing critical paths: After crashing an activity, the critical path may change. The exam may test your understanding of this concept.
4. Consider resource constraints: Some questions may include resource availability limitations that affect your crashing options.
5. Understand the limits of crashing: Be aware that each activity has a maximum possible compression (crash duration).
6. Remember overhead costs: Some questions may include daily project overhead costs, which should be factored into the total cost analysis.
7. Pay attention to constraints: Questions may include deadlines or budget constraints that limit crashing options.
8. Look for distractors: Exam questions may include non-critical activities as options to test if you understand that crashing these won't affect the schedule.
9. Consider the question context: Some questions may ask for the most cost-effective approach to meet a specific deadline rather than the maximum possible compression.
10. Remember the formula: Be prepared to calculate crash cost per unit time = (Crash Cost - Normal Cost) ÷ (Normal Duration - Crash Duration).
By mastering the concept of crashing and practicing these exam strategies, you'll be well-prepared to tackle PMI-SP exam questions on this important schedule compression technique.
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