CDT505 Chap.9 Agile Planning and Critical Chain
Agile Planning and Critical Chain
Match the method to the source of uncertainty
Agile planning uses short iterations, ordered backlog work and frequent feedback when requirements become clearer through delivery. Critical chain addresses resource conflicts and task-level safety by identifying the resource-feasible controlling chain and pooling protection into feeder and project buffers. These approaches can coexist, but they solve different problems.
Iteration supports learning; buffer management protects flow and the promised finish.
Design the interface when methods coexist
Some work can iterate while external approvals, procurement or statutory requirements remain fixed. Define which increment supplies evidence to the fixed milestone, what can still change and which owner accepts the handoff.
Critical chain requires resource conflicts to be resolved before the chain is named, and buffer status must be compared with honest remaining-duration estimates. A useful recommendation therefore names the uncertainty, mechanism and operating condition. Without that link, Agile and critical chain become labels rather than controls.
What this chapter covers
- 01
Agile origins and use conditions
- 02
Product backlog and sprint cycles
- 03
Reviews, retrospectives and feedback
- 04
Theory of Constraints
- 05
Critical path against critical chain
- 06
Feeder, project and capacity buffers
Worked example · free
Combine feedback with bottleneck control
- 3Separate requirement uncertainty from resource scarcity.
- 2Assign an Agile mechanism to learning.
- 3Assign a flow and buffer mechanism to the bottleneck.
Key terms
- Sprint
- A short iteration in which selected backlog work is planned, delivered and reviewed.
- Product Backlog
- An ordered list of desired product work that changes as learning and priority change.
- Theory of Constraints
- An approach that improves system performance by identifying and managing the binding constraint.
- Critical Chain
- The resource-feasible sequence that governs project duration under critical chain scheduling.
- Feeder Buffer
- Schedule protection placed where a non-critical path feeds into the critical chain.
Agile Planning and Critical Chain FAQ
How should Agile work connect to a fixed milestone?
Map the backlog item and increment to the evidence required by the milestone, identify the scarce resource and relevant feeder or project buffer, and name the acceptance owner. When priority changes, state which delivery date or buffer status changes too. The interface must exchange usable planning evidence rather than merely combine terminology from two methods.
When is Agile project management useful?
It is useful when requirements can be refined through frequent delivery and meaningful user feedback, and when work can be divided into valuable increments. It does not remove dependencies, fixed approvals or scarce-resource constraints.
How is critical chain different from critical path?
Critical path is derived from dependency logic and durations. Critical chain also resolves resource constraints, then protects the controlling sequence with pooled buffers. The chain can differ from the original critical path when scarce resources force activities apart.
What does a project buffer do?
It places shared schedule protection after the critical chain to protect the promised completion date. Tracking how quickly that buffer is consumed compared with progress provides a management signal, though the escalation threshold depends on the project's policy.
Assessment move
Classify uncertainty before choosing a method. For several short cases, mark whether learning concerns requirements, estimates, dependency logic, external approvals or scarce resources. Use Agile practices only where an increment and feedback can change priority or design. Write a small product backlog, choose a sprint goal and define what a review can genuinely teach.
Add a fixed external dependency to see where iteration needs a plan-driven interface. For critical chain practice, begin with a normal network and identify resource conflicts. Resolve those conflicts before tracing the resource-feasible controlling sequence. Replace scattered task-level protection with a project buffer at the end and feeder buffers where side paths join.
Draw the result and explain which promised date each buffer protects. Compare buffer consumption with work progress and state an investigation trigger without pretending that one universal threshold applies. Build a combined case where frequent user feedback is valuable but one specialist serves several products.
Keep backlog reprioritisation for learning, limit work in progress at the bottleneck and manage the chain through visible protection. Explain why additional ceremonies do not create capacity and why freezing all requirements would discard useful feedback.
Review key terms by pairing each with its operating condition: empowered product ownership and frequent feedback for iterative planning, disciplined priorities and visible constraints for critical chain. End every recommendation with the mechanism, the constraint it addresses and the condition required for success. If the same sentence could recommend either method without changing a noun, the diagnosis is still too vague.
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