Zoo Relocation Project—Part 3: WBS, Schedule and Critical Path

18 months, a zero-casualty mandate, a reuse-enclosures instruction, and a staged-closure strategy that overlaps planning with execution. Part 3 builds the WBS, network diagram, and critical path.

Series recap. Parts 1–2 produced the Charter, Stakeholder Engagement Plan, and Communications Plan. Part 3 enters the technical heart of project planning: scope decomposition and schedule construction.

The Challenge

The CEO's letter contains requirements that, on paper, do not fit in the available time:

These requirements are not all satisfiable under a naive waterfall schedule. The project must be broken into overlapping workstreams — fast-tracking in PMBOK language, phased delivery in heavy-engineering practice.

The PM Framework Applied

Step 1: Scope Baseline — Scope Statement → WBS → WBS Dictionary

PMBOK's Scope Management (Chapter 5) makes the sequencing explicit. The scope baseline consists of three artefacts:

1. Project Scope Statement — a prose document of scope, deliverables, acceptance criteria, exclusions, constraints, and assumptions.
2. WBS — hierarchical decomposition of scope into deliverables and work packages.
3. WBS Dictionary — detailed information per WBS element.

The scope statement must name what is out of scope: ongoing operation of the new site beyond opening, long-term animal husbandry training programs, capital fundraising beyond sale proceeds, legal disputes from the site handover. Declaring exclusions is how the PM prevents the project absorbing tasks that belong to business-as-usual.

Step 2: Build the WBS

A WBS decomposes project deliverables into progressively smaller components until each bottom-level element (a work package) is small enough to be estimated, assigned, and tracked. The 8/80 rule: no work package under 8 hours or over 80 hours.

1.0 Zoo Relocation Project

1.1 Project Management

1.2 Old Site Sale

1.3 New Site Acquisition

1.4 Design & Construction

1.5 Salvage & Asset Transfer

1.6 Animal Relocation

1.7 Staff Transition

1.8 Opening & Commissioning

1.9 Project Closure

1.1.1 Planning & Control

1.1.2 Stakeholder & Comms

1.1.3 Risk Management

1.1.4 Governance Reporting

1.6.1 Welfare Protocols

1.6.2 Transport Procurement

1.6.3 Regulatory Approvals

1.6.4 Staged Species Moves

1.6.5 Quarantine & Monitoring

Relationship details

From	Relationship	To
1.0 Zoo Relocation Project	leads to	1.1 Project Management
1.0 Zoo Relocation Project	leads to	1.2 Old Site Sale
1.0 Zoo Relocation Project	leads to	1.3 New Site Acquisition
1.0 Zoo Relocation Project	leads to	1.4 Design & Construction
1.0 Zoo Relocation Project	leads to	1.5 Salvage & Asset Transfer
1.0 Zoo Relocation Project	leads to	1.6 Animal Relocation
1.0 Zoo Relocation Project	leads to	1.7 Staff Transition
1.0 Zoo Relocation Project	leads to	1.8 Opening & Commissioning
1.0 Zoo Relocation Project	leads to	1.9 Project Closure
1.1 Project Management	leads to	1.1.1 Planning & Control
1.1 Project Management	leads to	1.1.2 Stakeholder & Comms
1.1 Project Management	leads to	1.1.3 Risk Management
1.1 Project Management	leads to	1.1.4 Governance Reporting
1.6 Animal Relocation	leads to	1.6.1 Welfare Protocols
1.6 Animal Relocation	leads to	1.6.2 Transport Procurement
1.6 Animal Relocation	leads to	1.6.3 Regulatory Approvals
1.6 Animal Relocation	leads to	1.6.4 Staged Species Moves
1.6 Animal Relocation	leads to	1.6.5 Quarantine & Monitoring

Two deliberate choices: Project Management (1.1) is itself a WBS element — PM activities consume real resources and must be visible in the WBS. Animal Relocation (1.6) is a top-level element — on a project where welfare is the dominant quality constraint, hiding it inside "Operations" is how zero-casualty commitments become 98% casualty rates.

Step 3: Decompose to work package level

Taking branch 1.6:

Each row passes 8/80, has a single named responsible party, and has a measurable completion criterion.

Step 4: Sequence into a network diagram

The WBS says what. It says nothing about when. Scheduling begins by identifying dependencies. The four dependency types from PMBOK are Finish-to-Start (most common), Start-to-Start, Finish-to-Finish, and Start-to-Finish (rare).

Charter Signed

Site Selection

Old Site Sale

Lease Signed

Permits

Design

Salvage

Construction

Staff Transition

Stage 1 Move

Public Closure

Stage 2 Move

Commissioning

Opening

Relationship details

From	Relationship	To
Start	leads to	Charter Signed
Charter Signed	leads to	Site Selection
Charter Signed	leads to	Old Site Sale
Site Selection	leads to	Lease Signed
Lease Signed	leads to	Permits
Lease Signed	leads to	Design
Old Site Sale	leads to	Construction
Design	leads to	Construction
Salvage	leads to	Construction
Permits	leads to	Stage 1 Move
Construction	leads to	Stage 1 Move
Charter Signed	leads to	Staff Transition
Stage 1 Move	leads to	Public Closure
Public Closure	leads to	Stage 2 Move
Stage 2 Move	leads to	Commissioning
Staff Transition	leads to	Commissioning
Commissioning	leads to	Opening
Opening	leads to	End

Red nodes are the critical path — the longest chain of dependent activities, which determines minimum project duration. A one-day delay to any critical-path activity delays the project by one day.

Step 5: Calculate the critical path

Definition — Critical Path. The sequence of activities that determines the minimum project duration. Critical-path activities have zero total float.

Formally, via forward and backward passes:

$$TF_{i} = LS_{i} - ES_{i} = LF_{i} - EF_{i}$$

For large projects the arithmetic is done by scheduling software (Primavera P6, MS Project). What the PM must understand is the implication: critical-path activities demand disproportionate management attention, and adding resources to non-critical activities is usually a waste of money.

Step 6: Fast-track or crash where required

• Fast-tracking — overlapping sequential activities. Costs nothing but increases rework risk.
• Crashing — adding resources to critical-path activities. Costs money, yields diminishing returns.

For the Zoo, fast-tracking might mean beginning salvage of low-risk assets before public closure. Crashing might mean running two construction crews in parallel. Both decisions must be logged against risk.

Step 7: Baseline the schedule

Workstream	Activity	Type	Timing / dependency / duration
Initiation	Charter & Stakeholder	Activity	done · init · 2025-01-01 · 30d
Finance & Site	Old Site Sale	Activity	active · sale · 2025-01-15 · 330d
Finance & Site	New Site Selection	Activity	active · site · 2025-02-01 · 90d
Finance & Site	Lease Execution	Milestone	milestone · lease · after site · 0d
Finance & Site	Regulatory Permits	Activity	crit · perm · after lease · 120d
Design & Build	New Site Design	Activity	crit · des · after lease · 90d
Design & Build	Construction Phase 1	Activity	crit · b1 · after des · 150d
Design & Build	Construction Phase 2	Activity	crit · b2 · after b1 · 120d
Animal Relocation	Welfare Protocols	Activity	wp · 2025-03-01 · 90d
Animal Relocation	Stage 1 Moves	Activity	s1 · after b1 · 60d
Animal Relocation	Public Closure	Milestone	milestone · closure · after s1 · 0d
Animal Relocation	Stage 2 Moves	Activity	crit · s2 · after closure · 120d
Animal Relocation	Quarantine	Activity	quar · after s2 · 60d
Commissioning	Commissioning	Activity	crit · comm · after quar · 60d
Commissioning	Public Opening	Milestone	milestone · open · after comm · 0d

Work Breakdown Structure

1.0 Project

1.1 Design

1.2 Procurement

1.3 Build

1.4 Test

Derived Schedule

Design Task

Procurement Task

Build Task

Test Task

Relationship details

From	Relationship	To
1.0 Project	leads to	1.1 Design
1.0 Project	leads to	1.2 Procurement
1.0 Project	leads to	1.3 Build
1.0 Project	leads to	1.4 Test
Design Task	leads to	Procurement Task
Procurement Task	leads to	Build Task
Build Task	leads to	Test Task
1.1 Design	leads to	Design Task
Design Task	leads to	link
1.2 Procurement	leads to	Procurement Task
Procurement Task	leads to	link
1.3 Build	leads to	Build Task
Build Task	leads to	link
1.4 Test	leads to	Test Task
Test Task	leads to	link

The Result

Four additional controlled artefacts: Scope Statement, WBS, WBS Dictionary, Baselined Project Schedule. Together with the charter and stakeholder plan, these constitute the performance measurement baseline for scope and schedule.

The Pitfalls

• Skipping the scope statement. Leaves the WBS with no textual anchor.
• Decomposing by department rather than deliverable. A WBS organised by "Engineering, HR, Finance" is an org chart, not a WBS.
• Omitting project management from the WBS. PM is work; work must be in the WBS.
• Wrong work package sizing. Over 80 hours cannot be estimated accurately; under 8 hours generates tracking overhead exceeding its value.
• Confusing the WBS with the schedule. The WBS has no time dimension.
• Fast-tracking without risk analysis. Overlapping previously sequential activities always increases risk.
• Treating the baseline as unchangeable. The baseline is the reference for measuring change, not a prohibition against it.

Knowledge Check

1. The site sale takes 14 months instead of 12. Which downstream activities are affected, and does the critical path change?
2. The lead transport contractor goes into administration two weeks before Stage 2. Which work packages are affected, and what are your options?
3. During the forward pass you discover construction has 45 days of float but the permit activity has 0. The construction manager asks for an additional crew. How do you respond?

Key Takeaways

• The scope baseline comprises the Scope Statement, WBS, and WBS Dictionary — all three required.
• The WBS decomposes into deliverables, not activities.
• Work packages must obey the 8/80 rule.
• Project management itself is a WBS element.
• The critical path is the longest chain of dependent activities through the network.
• Schedule compression is achieved through fast-tracking or crashing — both carry risk implications.

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References

• Project Management Institute 2017, A Guide to the Project Management Body of Knowledge (PMBOK Guide), 6th edn, PMI, Newtown Square, PA.
• Kerzner, H 2017, Project Management: A Systems Approach, 12th edn, Wiley, Hoboken, NJ.
• Burke, R 2013, Project Management: Planning and Control Techniques, 5th edn, Wiley, Chichester.
• Lewis, JP 2011, Project Planning, Scheduling and Control, 5th edn, McGraw-Hill, New York.
• University of South Australia 2015, MPM411 Zoo Relocation Project Brief, UniSA, Adelaide.