--- title: "Method of quantity estimate for road" subject: "Estimating and Costing" chapter: 6 key: "semester_7/estimating_and_costing:road-method-quantity-explain" source: https://www.bctengineer.com/q/semester_7/estimating_and_costing/road-method-quantity-explain site: BCT Engineering --- # Method of quantity estimate for road Estimating and Costing · Chapter 6: Detailed Estimate - Asked in: 2079 Bhadra, 2 marks - Video: [Road Estimation-1# Method used in road estimation.](https://www.youtube.com/watch?v=q3yaF-two8U) — TECHNICA ONLINE LECTURES - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_7/estimating_and_costing/road-method-quantity-explain - Whole chapter: https://www.bctengineer.com/md/semester_7/estimating_and_costing/chapter-6 ## Question Briefly explain the method of quantity estimate for road construction. ## Short answer Take cross-sections at regular intervals, finding cut/fill depths from ground and formation levels. Calculate sectional areas using formation width and side slopes, then compute volumes by mean area or prismoidal method and add pavement layers. ## Answer Quantities of road earthwork are found from the longitudinal section and cross-sections. 1. Take cross-sections at regular intervals (e.g. 10–30 m, closer on curves) and at points where the ground changes. 2. Find the depth of cutting or height of filling at the centre line from the ground level and formation level; the formation level follows the design gradients. 3. For each section calculate the area of cutting and filling from the formation width and side slopes ($A = (B + s h)h$ for level ground; side-hill formulae when the ground has a cross slope). 4. Find the volume between consecutive sections by the **mean sectional area** method ($V = \tfrac{A_1 + A_2}{2} \times L$), or the prismoidal formula for greater accuracy. 5. Add the quantities of pavement layers (area × thickness), drains, culverts and protection works, and put everything in a bill of quantities. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Road earthwork quantities are found mainly from: A. Longitudinal section and cross-sections B. Only the plan C. Only the bill of quantities D. Market rates Answer: A. Depths from the longitudinal section and areas from cross-sections give the earthwork. (Key point: Data source) 2. The usual method to get volume between two cross-sections is: A. Mean sectional area x distance between them B. Smaller area x distance C. Sum of areas x distance D. Product of areas Answer: A. V = (A1 + A2)/2 x L; the prismoidal formula is used for greater accuracy. (Key point: Volume method) 3. Where should cross-sections be taken? A. At regular intervals, closer on curves, and wherever the ground changes B. Only at the start and end of the road C. Only at bridges D. At 1 km intervals Answer: A. Sections at regular intervals (10-30 m), closer on curves and at changes of ground, represent the ground properly. (Key point: Section spacing) 4. After earthwork, what else is added to the quantities of a road estimate? A. Pavement layers, drains, culverts and protection works B. Only labour rates C. Only overhead D. Nothing Answer: A. Pavement layers (area x thickness), drains, culverts and protection works are added and listed in a bill of quantities. 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