Scheduling methods: bar chart / Gantt, CPM, milestone chart compared

One-line orientation

Scheduling tools differ in whether they show task dependencies and the critical path — CPM is the exam-relevant method because it identifies exactly which activities control the project completion date.

Key points

• Bar chart / Gantt chart:
  • Tasks listed vertically, time horizontally; each task shown as a bar.
  • Shows what is happening at any point in time and the sequence of tasks.
  • Easy to create, easy to read; suitable for projects of any size.
  • A plain Gantt chart does not show task dependencies or the critical path. Modern scheduling software may add dependency links to a Gantt display.
• Milestone chart:
  • Plots only key milestone events (phase completions, permit dates, owner approvals) on a timeline.
  • No task bars or logic; suitable for short projects with few tasks or for executive-level reporting.
• Critical Path Method (CPM):
  • The Critical Path Method (CPM) links tasks by their dependencies, then shows which sequence controls the earliest completion date.
  • Each task is represented by an arrow (solid); numbered circles mark the beginning and ending points of each activity.
  • A task cannot start until all tasks leading into its start node are complete.
  • Dependency: a relationship where one task must finish before another can start.
  • Critical Path: the longest sequence of dependent activities from start to finish. The sum of durations on this path equals the minimum project duration.
  • Float (slack): the amount of time a non-critical activity can slip without delaying the project. Critical-path activities have zero float.
  • Dummies: dashed arrows showing dependency relationships only — no duration, no work. Used in arrow-diagramming method networks to preserve unique activity numbering.
  • Delays to any critical-path task delay the project; delays to non-critical tasks may not (as long as they stay within their float).
  • Essential for CMc delivery and fast-track projects; typically software-generated on large jobs.

Gantt timing vs CPM (critical path method) topology

The same schematic nine-day schedule: neutral bars above, dependency arrows below

View diagram Hide diagram

Scroll horizontally to explore →

A plain Gantt chart does not prove dependencies or identify the critical path.

A dummy carries a logical dependency only — no duration, no work — so each activity keeps unique node numbers.

Confusions / comparison

	Bar chart / Gantt	CPM network	Milestone chart
Shows dependencies / logic?	No	Yes	No
Shows critical path / float?	No	Yes	No
Level of complexity	Simple	Detailed	Minimal
Best for	Any project; easy communication	Large, complex projects; fast-track / CMc	Short projects; executive summaries

Related

→ pp-fast-track-scheduling (this module): fast-track projects require CPM to manage overlapping design and construction packages · pp-construction-payment-basis (this module): CMc/GMP delivery commonly uses CPM · ProPractice — work plan and fee monitoring: design schedules are commonly shown as Gantt charts; CPM is for construction.