---
title: "Rate analysis: 10 cm compacted gravel subgrade"
subject: "Estimating and Costing"
chapter: 4
key: "semester_7/estimating_and_costing:rate-gravel-subgrade-10cm"
source: https://www.bctengineer.com/q/semester_7/estimating_and_costing/rate-gravel-subgrade-10cm
site: BCT Engineering
---

# Rate analysis: 10 cm compacted gravel subgrade

Estimating and Costing · Chapter 4: Analysis of Rates

- Asked in: 2081 Baisakh, 5 marks
- Video: [How to calculate Granular Sub-Base (GSB) quantity with Compaction Factor](https://www.youtube.com/watch?v=tCs8D_NWFzg) — Civil Field Engineer
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/estimating_and_costing/rate-gravel-subgrade-10cm
- Whole chapter: https://www.bctengineer.com/md/semester_7/estimating_and_costing/chapter-4

## Question

Prepare analysis of rates for providing, laying and consolidation of 10 cm thick compacted gravel for sub grade per square meter.

## Short answer

Compacted volume is 0.1 m3/m2, loose volume factor 1.30. For 100 m2, gravel 13 m3, unskilled 4 md, skilled 0.5 md, roller 0.5 hr. Rate = Rs 529.58 per m2, excluding VAT.

## Answer

#### Basis
Rate for **providing, laying and consolidating 10 cm thick compacted gravel in the sub-grade**, worked out for **100 m²** and divided for 1 m². Assumptions (illustrative, in the style of Department of Roads norms):
- Compacted volume = 100 x 0.10 = 10.0 m³; loose volume = compacted x 1.30 (compaction factor) = 13.0 m³.
- Water for compaction = 12% of compacted volume = 1.20 m³.
- Labour 0.4 unskilled md per m³ and 0.05 skilled md per m³ of compacted gravel; roller 0.05 hr per m³.

#### Analysis (per 100 m²)
| Description | Qty | Unit | Rate (Rs) | Amount (Rs) |
|---|---|---|---|---|
| Gravel (sub-base grade), loose 13.00 m³ | 13 | m³ | 3,000.00 | 39,000.00 |
| Labour: spreading, levelling (unskilled) | 4 | md | 900.00 | 3,600.00 |
| Labour: skilled (grade checker / roller operator helper) | 0.5 | md | 1,200.00 | 600.00 |
| Water for compaction (1.20 m³) | 1.2 | m³ | 500.00 | 600.00 |
| 10-t vibrating roller, 0.50 hr | 0.5 | hr | 4,500.00 | 2,250.00 |
| **Sub-total** | | | | **46,050.00** |
| Contractor's overhead and profit | 15% | | | 6,907.50 |
| **Total per 100 m²** | | | | **52,957.50** |

**Answer: Rate = 52,957.50 / 100 = Rs 529.58 per m²** (excluding VAT).

## Check yourself

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

1. For 100 m^2 of 10 cm compacted gravel, how much loose gravel is paid for?
   A. 10.0 m^3, equal to the compacted volume
   B. 7.7 m^3, as 10.0/1.30
   C. 13.0 m^3, as compacted 10.0 m^3 x 1.30
   D. 1.2 m^3, from the water allowance
   Answer: C. Gravel is bought loose, so compacted volume is multiplied by the compaction factor 1.30 to give 13.0 m^3. (Key point: Loose vs compacted volume)

2. How is the water quantity found?
   A. 12% of the loose volume = 1.56 m^3
   B. 12% of the compacted volume = 1.20 m^3
   C. 1.30 x 10.0 = 13 m^3
   D. 0.05 m^3 per m^3 of gravel
   Answer: B. Water is taken as 12% of the compacted volume of 10.0 m^3, which is 1.20 m^3. (Key point: Water for compaction)

3. The total per 100 m^2 is Rs 52,957.50 including 15% overhead and profit. What is the rate per m^2?
   A. Rs 529.58, dividing by 100
   B. Rs 5,295.75, dividing by 10
   C. Rs 46,050 / 100 = Rs 460.50
   D. Rs 52,957.50 x 100
   Answer: A. The rate for 100 m^2 is divided by 100 to give Rs 529.58 per m^2. (Key point: Per m^2 rate)

## Close variants set in other exams

- [Rate analysis: 30 cm compacted gravel subgrade](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Arate-gravel-subgrade-30cm) — Estimating and Costing, chapter 4, asked 2×