---
title: "Short note: Telford construction"
subject: "Transportation Engineering I"
chapter: 1
key: "semester_6/transportation_engineering_i:telford-note"
source: https://www.bctengineer.com/q/semester_6/transportation_engineering_i/telford-note
site: BCT Engineering
---

# Short note: Telford construction

Transportation Engineering I · Chapter 1: Introduction to Transportation Planning and engineering

- Asked in: 2063 Kartik (old course), 4 marks
- Video: [Telford road construction ](https://www.youtube.com/watch?v=iKCEokVrbrE) — Civion
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/transportation_engineering_i/telford-note
- Whole chapter: https://www.bctengineer.com/md/semester_6/transportation_engineering_i/chapter-1

## Question

Write a short note on Telford construction.

## Short answer

Telford construction places large hand-set stones on edge as a foundation, covered by layers of broken stone, totaling about 400-450 mm. It provides a very strong road on weak soil but is slow and expensive, replaced by Macadam's method.

## Answer

**Telford construction** was developed by the Scottish engineer Thomas Telford (1757-1834) in the early 1800s. It builds the road on a strong foundation of large stones to carry the load and keep out moisture from the subgrade.

#### Features
- **Foundation layer:** large stones (about 170-250 mm), set by hand on edge with the broader face down and narrower end up; gaps are filled with small stones and well rammed.
- **Middle layer:** about 100 mm of broken stone (about 65 mm size) over the foundation.
- **Top layer:** about 40 mm of smaller stone (about 25 mm) with binding material.
- The subgrade is nearly **flat or slightly cambered;** the cross slope is made by the varying thickness of the stones; the crown is about 1 in 45 to 1 in 60, with side drains.
- **Total thickness** about 400-450 mm.

```text
   ___ 40 mm top layer ___
   === 100 mm broken stone ===
   ##### hand-set stones #####
   ------ flat subgrade ------
```

#### Merits and demerits
- Strong, durable and good for weak soil.
- But costly and slow because of skilled hand-setting, so Macadam's cheaper method replaced it.

## Check yourself

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

1. How is the Telford foundation laid?
   A. Loose stones dumped randomly
   B. Large stones (170-250 mm) set by hand on edge with the broader face down and gaps filled with small stones
   C. Concrete poured
   D. Sand layer
   Answer: B. Telford's foundation uses large hand-set stones on edge with gaps filled and rammed. (Key point: Foundation layer)

2. What is the approximate total thickness of Telford construction?
   A. About 100 mm
   B. About 250 mm
   C. About 400-450 mm
   D. About 1000 mm
   Answer: C. The total is about 400-450 mm. (Key point: Total thickness)

3. How is the cross slope achieved in Telford construction?
   A. Strongly cambered subgrade
   B. By the varying thickness of the stones, with a nearly flat subgrade
   C. By steep side slopes
   D. Not provided at all
   Answer: B. The subgrade is nearly flat and the crown (1 in 45 to 1 in 60) is formed by varying stone thickness. (Key point: Camber of subgrade)

4. Why was Telford construction replaced by Macadam's method?
   A. It was weak
   B. It was too cheap
   C. It was costly and slow because of skilled hand-setting
   D. It could not carry traffic
   Answer: C. Telford was strong but costly and slow, so Macadam's cheaper method replaced it. (Key point: Demerit)

## Related in Transportation Engineering I

- [Macadam versus Telford construction](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Amacadam-vs-telford) — Transportation Engineering I, chapter 1, asked 2×