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IND6132A — Planning et suivi de projets technologiques · Polytechnique Montréal

Critical Path Scheduling: Bike-Shop Renovation

A scheduling exercise built around a real-world brief: a client wants to convert a former restaurant in Montréal into a specialty shop for selling and repairing electric bikes. The job was to plan the entire renovation using the Critical Path Method (CPM), from first principles through to a working Microsoft Project schedule.

CPMWBSAONMS ProjectGantt chart

Done in pair with Olivier B. — IND6132A, Sept. 2023

How this schedule came together

Step 1 of 5 — click a milestone to explore it

Reading the briefWeek 1

Unpacked the client's ask — converting a former restaurant into an e-bike sales-and-repair shop — into clear needs, a budget envelope, and a rough sense of how long the renovation should take.

Figure 1 — Work Breakdown Structure (WBS) for the bike-shop conversion, organized into 5 top-level work packages.
Figure 2 — Layout sketch of the renovated space: sales floor, workshop, stock, counter, and storefront terrace.
Figure 3 — Activity-on-Node (AON) network with early/late start & finish times — the basis for our hand-calculated critical path.
Figure 4 — Resulting Gantt chart generated in Microsoft Project, confirming a 76-working-day critical path.
Figure 5 — How we organized ourselves as a team: read & split the brief, build the WBS, validate it, and loop back until the result held up.

The brief

The bike sector in Canada has been growing steadily, with revenues approaching $1.5 billion. A market study identified a strong opportunity in Montréal to convert an old restaurant space into a shop specializing in electric bikes — sales and repair. Our task was to take the architect's sketch of the renovated space and turn it into a realistic, defensible project schedule.

Work breakdown structure (WBS)

We split the renovation into 7 work packages, each documented in a WBS dictionary describing scope, dependencies, and deliverables:

  • 1
    Plans & studies — Defining the client's needs, budget, and estimated project duration.
  • 2
    Design & preparation — Pre-construction activities, including first costs engaged with subcontractors.
  • 3.1
    Site preparation — Everything needed to ready the restaurant for the construction crews.
  • 3.2
    Interior & exterior works — The bulk of the work — the shop physically takes shape.
  • 3.3
    Fit-out — Final interior/exterior finishing and decoration to welcome staff, stock, and customers.
  • 4
    Project management — Coordinating contractors, scheduling resources, and reporting at three key milestones.
  • 5
    Store opening — Everything outside of construction needed to launch — staff training through pre-opening advertising.

Applying the CPM algorithm

With the WBS in place, we built an Activity-on-Node (AON) network, working under the standard CPM assumptions — deterministic environment, no resource constraints, and uninterrupted activities. We calculated task durations, predecessors, and total float by hand, then cross-checked the result against Microsoft Project.

Result

Our manual critical-path calculation and MS Project both converged on a minimum project duration of 76 working days. MS Project's calendar view showed a longer elapsed duration because it excludes weekends — a small but important detail in reconciling theoretical and tool-based results. Based on a target completion of March 28, 2025, this placed the ideal start date at December 13, 2024.

What this taught me

  • How to translate a vague client brief into a structured, defensible WBS
  • Building and reading an AON network, and computing the critical path and total float by hand
  • Reconciling manual calculations against software output — and explaining the gap (calendar vs. working-day assumptions)
  • Why the WBS has to double as shared vocabulary for the whole project team, not just a planning artifact for the manager

Reference

Our WBS approach was grounded in Shlomo Globerson's "Impact of various work-breakdown structures on project conceptualization" — the idea that the WBS is the skeleton of a project, and that getting it right shapes everything that follows.

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