---
title: "When to use bar chart, CPM, PERT"
subject: "Project Engineering"
chapter: 3
key: "semester_7/project_engineering:bar-chart-cpm-pert-situations"
source: https://www.bctengineer.com/q/semester_7/project_engineering/bar-chart-cpm-pert-situations
site: BCT Engineering
---

# When to use bar chart, CPM, PERT

Project Engineering · Chapter 3: Project Planning and Scheduling

- Asked in: 2079 Baisakh
- Video: [ARE 5.0 -  Critical Path Method and Gantt Charts](https://www.youtube.com/watch?v=MylEHNnc3ho) — Hyperfine Architecture
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/project_engineering/bar-chart-cpm-pert-situations
- Whole chapter: https://www.bctengineer.com/md/semester_7/project_engineering/chapter-3

## Question

In which situations do we have to use a bar chart, CPM and PERT for scheduling of a project?

## Short answer

Bar chart: small, simple projects (e.g., house) needing a quick, easy schedule. CPM: large, familiar projects (roads, bridges) with certain durations, needed for critical path and resource scheduling. PERT: novel, uncertain projects (hydropower tunnels, R&D) with three duration estimates, for finding completion probability.

## Answer

The method is chosen according to the size of the project, nature of the activities and the certainty of the time estimates.

#### Bar chart
Use it when:
- the project is small, simple or has few activities (a house, a small culvert);
- a quick, easy-to-read schedule is needed for site staff or for a presentation to top management;
- the work is at the preliminary stage and the logic is not yet detailed;
- progress is to be shown to people without technical training.

#### CPM (Critical Path Method)
Use it when:
- the project is large and complex, with many inter-related activities, but the durations can be estimated with fair certainty from experience (roads, buildings, bridges, canals);
- the critical path and floats are needed;
- time-cost trade-off (crashing) and resource scheduling are required;
- the project is repetitive or similar projects were done before.

#### PERT (Programme Evaluation and Review Technique)
Use it when:
- the work is new, research-type or has no past data (first-of-its-kind hydropower, tunnelling, software, defence projects);
- activity durations are uncertain and three estimates (optimistic, most likely, pessimistic) are needed;
- the probability of finishing the project by a given date is to be found;
- the main interest is time, not cost.

| Basis | Bar chart | CPM | PERT |
|---|---|---|---|
| Project | Small, simple | Large, familiar | Large, new, uncertain |
| Time estimate | Single | Single (deterministic) | Three (probabilistic) |
| Logic shown | No | Yes | Yes |
| Critical path | No | Yes | Yes |

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. When is a bar chart suitable?
   A. For first-of-its-kind research projects needing probabilities
   B. For small, simple projects or preliminary stage where an easy-to-read schedule is needed
   C. For large projects needing time-cost trade-off
   D. For finding the chance of finishing by a date
   Answer: B. Bar charts suit small projects and presentations to non-technical people. (Key point: Bar chart use)

2. Which situation calls for CPM?
   A. Large complex project with fairly certain durations from experience, needing critical path and crashing
   B. A new project with no past data
   C. A project needing three time estimates
   D. A very small culvert shown to site staff
   Answer: A. CPM is deterministic and supports critical path, floats, crashing and resource scheduling. (Key point: CPM use)

3. Which situation calls for PERT?
   A. Repetitive projects done many times before
   B. A simple house shown on one page
   C. New, research-type work with uncertain durations where probability of meeting a date is needed
   D. Work where only cost matters
   Answer: C. PERT uses optimistic, most likely and pessimistic estimates and gives probabilities. (Key point: PERT use)

4. Which statement about time estimates is correct?
   A. All three use three estimates
   B. Only the bar chart uses three estimates
   C. CPM uses three and PERT uses one
   D. Bar chart and CPM use a single estimate; PERT uses three
   Answer: D. CPM is deterministic with a single estimate; PERT is probabilistic with three. (Key point: Comparison)

## Related in Project Engineering

- [Planning, scheduling; linked bar chart](https://www.bctengineer.com/question.md?key=semester_7%2Fproject_engineering%3Aplanning-scheduling-linked-bar-chart) — Project Engineering, chapter 3
- [Bar chart of irrigation project with milestones](https://www.bctengineer.com/question.md?key=semester_7%2Fproject_engineering%3Abar-chart-irrigation-milestones) — Project Engineering, chapter 3
- [Difference between CPM and PERT](https://www.bctengineer.com/question.md?key=semester_7%2Fproject_engineering%3Acpm-vs-pert-difference) — Project Engineering, chapter 3, asked 2×
- [CPM and PERT and their uses](https://www.bctengineer.com/question.md?key=semester_7%2Fproject_engineering%3Acpm-pert-uses) — Project Engineering, chapter 3
- [CPM vs PERT; te and variance for x, y](https://www.bctengineer.com/question.md?key=semester_7%2Fproject_engineering%3Acpm-pert-te-variance-x-y) — Project Engineering, chapter 3
- [Planning in dynamic environment; linked bar chart](https://www.bctengineer.com/question.md?key=semester_7%2Fproject_engineering%3Aplanning-necessary-dynamic-linked-bar) — Project Engineering, chapter 3

## Related in other subjects

- [Bar chart vs CPM/PERT as planning tool](https://www.bctengineer.com/question.md?key=semester_8%2Fconstruction_management%3Aplanning-tool-choice) — Construction Management, chapter 2, asked 3×
- [Difference between CPM and PERT](https://www.bctengineer.com/question.md?key=semester_7%2Fict_project_management%3Acpm-vs-pert) — ICT Project Management, chapter 8
- [Difference between CPM and PERT](https://www.bctengineer.com/question.md?key=semester_6%2Findustrial_engineering_and_management%3Adifference-between-cpm-and-pert) — Industrial Engineering and Management, chapter 3
- [Chart vs table; bar vs pie graph](https://www.bctengineer.com/question.md?key=semester_5%2Fcommunication_english%3Adifferences-chart-table-bar-pie) — Communication English, chapter 4