Construction Management for SSC JE Civil: CPM, PERT, Float, Bar Charts, Tenders, Contracts and Construction Equipment
Rahul Kumar
SSC Exam Expert & Content Editor
In this note
- 1.Project Planning and Scheduling
- 2.CPM and PERT
- 3.Network Terms
- 4.PERT Time Estimates
- 5.Contracts
- 6.Tender Procedure
- 7.Documents and Bills
- 8.Construction Equipment (Selected)
- 9.Safety on Construction Sites
- 10.Solved Examples
- 11.Quick Tips
- 12.Quick Revision Points
- 13.Practice Questions With Answers
- 14.How to Practise This Chapter
- 15.Frequently Asked Questions
PDF Notes: Construction Management for SSC JE Civil: CPM, PERT, Float, Bar Charts, Tenders, Contracts and Construction Equipment
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Construction management deals with the planning, scheduling and control of a project and with the contract system. SSC JE Civil asks questions on CPM and PERT, float, bar charts, the types of contracts and the tender procedure. This guide on construction management for SSC JE covers all of them, with solved examples, practice questions and FAQs.
Project Planning and Scheduling
| Technique | Features |
|---|---|
| Bar chart (Gantt chart) | Developed by Henry Gantt (1917); shows the activities as horizontal bars against time; simple but does not show the interdependence of activities |
| Milestone chart | Shows the key events of a project |
| Network techniques (CPM and PERT) | Show the logical relationships between activities; used for large projects |
| Line of balance | Used for repetitive work such as housing and roads |
CPM and PERT
| Feature | CPM | PERT |
|---|---|---|
| Full form | Critical Path Method | Programme Evaluation and Review Technique |
| Origin | DuPont, USA (1957) | US Navy, for the Polaris missile project (1958) |
| Time estimates | One estimate (deterministic) | Three estimates (probabilistic): optimistic, most likely and pessimistic |
| Orientation | Activity-oriented | Event-oriented |
| Use | Construction projects where time is well known | Research and development projects with uncertain time |
| Cost | Time–cost trade-off (crashing) is a part of it | Mainly concerned with time |
Network Terms
| Term | Meaning |
|---|---|
| Activity | A task that needs time and resources; shown by an arrow in the Activity-on-Arrow (AOA) network |
| Event (node) | The start or the end of an activity; consumes no time |
| Dummy activity | Has no duration; shown by a dashed arrow; used to show the logic |
| Critical path | The longest path through the network; it decides the minimum duration of the project; the activities on it have zero total float |
| Earliest start time (EST) | The earliest time an activity can start (forward pass) |
| Latest start time (LST) or latest finish time (LFT) | The latest time without delaying the project (backward pass) |
| Total float | LST − EST (or LFT − EFT); the time by which an activity can be delayed without delaying the project |
| Free float | The delay possible without affecting the earliest start of the next activity |
| Independent float | The delay possible without affecting any other activity, even if the preceding activity ends late |
| Slack | The float of an event in PERT |
| Crashing | Reducing the time of the activities by adding resources at a higher cost |
PERT Time Estimates
- Expected time te = (to + 4tm + tp) / 6 (beta distribution), where to is optimistic, tm the most likely and tp the pessimistic time.
- Variance = ((tp − to) / 6)² and the standard deviation = (tp − to) / 6.
- The standard deviation of the project is the square root of the sum of the variances of the activities on the critical path.
- The probability of completing the project by a given time is found using the normal distribution Z = (Ts − Te) / σ.
Contracts
| Type of Contract | Features |
|---|---|
| Lump sum (fixed price) | A fixed total price for the whole work; the contractor bears the risk |
| Item rate (unit price) contract | The contractor quotes a rate per unit of each item; payment is based on the actual quantities |
| Percentage rate contract | Quote as a percentage above or below the estimate |
| Cost plus contract | The contractor is paid the actual cost plus a fee (fixed, percentage or sliding scale); used when the work cannot be defined in advance |
| Labour contract | Only labour is supplied by the contractor; the material is supplied by the owner |
| Turnkey contract | The contractor does the design, construction and handing over of a ready-to-use project (EPC and design-build) |
| Piece-work contract | Payment per piece or unit of work |
| BOT (Build, Operate and Transfer) | The contractor builds, runs for a period and then transfers to the owner |
Tender Procedure
- Preparation of the estimate and the tender documents.
- Invitation of the tender (notice inviting tender, NIT) through newspapers or e-procurement.
- Submission of the tenders by the contractors with the earnest money deposit (EMD), generally 1–2% of the estimated cost.
- Opening of the tenders and comparison of the rates; selection of the lowest responsive bidder.
- Award of the contract, security deposit (generally 5–10% of the contract value, which includes the performance guarantee), and signing of the agreement.
- Issue of the work order and starting the work.
Documents and Bills
| Document | Purpose |
|---|---|
| Measurement Book (MB) | Records the measurements of the work done; the basis of payment |
| Muster roll | Attendance and wages of the daily labour |
| Running Account (RA) bill | Interim payments during the work |
| Final bill | Payment after completion of the work |
| Completion certificate | Issued after the work is complete |
| Defect liability period | The period after completion in which the contractor must repair the defects |
| Retention money | A part of the bill kept back as a security |
| Arbitration | Settlement of disputes through an arbitrator under the Arbitration and Conciliation Act, 1996 |
Construction Equipment (Selected)
| Equipment | Use |
|---|---|
| Bulldozer | Pushing and levelling the earth |
| Scraper | Excavating, hauling and spreading the earth |
| Grader | Finishing and levelling surfaces; used in road construction |
| Dragline | Excavation below the machine level and underwater |
| Power shovel | Excavation above the machine level |
| Backhoe (hoe) | Digging trenches and below the ground level |
| Roller | Compaction of soil and bituminous layers |
| Transit mixer | Carries ready-mix concrete |
| Tower crane | Lifting materials in high-rise buildings |
Safety on Construction Sites
- Use of helmets, safety shoes and harnesses.
- Scaffolding and barricading of excavations.
- Safety rules are given in the Building and Other Construction Workers Act, 1996 and the BIS codes (IS 7969).
- The use of the first aid box and fire-fighting equipment.
Solved Examples
Example 1. For an activity, the optimistic time is 4 days, the most likely 6 days and the pessimistic 14 days. Find the expected time.
te = (4 + 24 + 14)/6 = 7 days.
Example 2. Find the variance of the same activity.
((14 − 4)/6)² = (1.667)² = 2.78.
Example 3. An activity has an EST of 5 days and an LST of 9 days. Find its total float.
9 − 5 = 4 days.
Example 4. What is the total float of the activities on the critical path?
Zero.
Quick Tips
- Memorise the PERT formulas te and the variance.
- Remember that the critical path has zero float and is the longest path.
- Learn the difference between CPM and PERT.
- Learn the main types of contracts with one feature each.
Quick Revision Points
- The critical path is the longest path with zero float.
- Total float = LST − EST.
- PERT: te = (to + 4tm + tp)/6.
- CPM is deterministic; PERT is probabilistic.
- EMD is usually 1–2% and security deposit 5–10%.
Practice Questions With Answers
- What does the critical path represent?
Answer: The longest path and the minimum project duration - What is the total float of critical activities?
Answer: Zero - What is the formula for the expected time in PERT?
Answer: (to + 4tm + tp)/6 - Who developed the bar chart?
Answer: Henry Gantt - Which contract pays the actual cost plus a fee?
Answer: Cost plus contract - What is the EMD?
Answer: Earnest money deposit - Which book records the measurements of work done?
Answer: Measurement Book - Which technique uses three time estimates?
Answer: PERT - Which machine is used for digging below the machine level (trenches)?
Answer: Backhoe (or dragline) - What is the total float?
Answer: LST − EST
How to Practise This Chapter
Practise 10 questions every day and write the steps on paper. Then attempt timed sets from our practice papers and the previous year papers page. See all topics on the Civil Engineering notes page, read the previous topic Irrigation Engineering and Hydrology.
Frequently Asked Questions
What is CPM?
The Critical Path Method, a network technique with a single time estimate for each activity.
What is PERT?
Programme Evaluation and Review Technique, a network technique with three time estimates.
What is the critical path?
The longest path in the network which decides the minimum project time.
What is float?
The spare time available to an activity without delaying the project.
What is a dummy activity?
An activity with zero duration used to show the logical dependence.
What is a bar chart?
A chart showing the activities as bars against time, developed by Henry Gantt.
What is a lump sum contract?
A contract at a fixed total price for the whole work.
What is an item rate contract?
A contract in which rates are quoted for each item and payment is for the quantities actually done.
What is EMD?
Earnest money deposit paid with the tender as a guarantee.
What is the Measurement Book?
The record of measurements of the work done by the contractor.
Is this topic asked in SSC JE?
Yes. Construction management is asked in SSC JE Civil.
What is crashing?
Reducing the project time by increasing the resources at extra cost.
Rahul Kumar
SSC Exam Expert & Content Editor
Rahul is a senior SSC exam strategist with 8+ years of experience helping aspirants crack CGL, CHSL and MTS exams. He writes in-depth notification breakdowns, exam pattern guides and preparation strategies.