--- title: "Macadam versus Telford construction" subject: "Transportation Engineering I" chapter: 1 key: "semester_6/transportation_engineering_i:macadam-vs-telford" source: https://www.bctengineer.com/q/semester_6/transportation_engineering_i/macadam-vs-telford site: BCT Engineering --- # Macadam versus Telford construction Transportation Engineering I · Chapter 1: Introduction to Transportation Planning and engineering - Asked in: 2066 Magh (old course); 2065 Chaitra (old course), 6 marks (asked 2 times) - Video: [Evolution of Roads: Roman, Telford, Macadam & Tresaguet Pioneering Road Designs| Transportation](https://www.youtube.com/watch?v=QP2vUW2iYvo) — OPengineer - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_6/transportation_engineering_i/macadam-vs-telford - Whole chapter: https://www.bctengineer.com/md/semester_6/transportation_engineering_i/chapter-1 ## Question Compare the main features of Telford and Macadam construction (why is Macadam road superior to Telford construction?). Make sketches of those road sections. ## Short answer Telford used a heavy hand-packed stone foundation (400–450 mm) on a flat subgrade; Macadam used thinner (250 mm) compacted angular stone on a cambered, drained subgrade with no special foundation. Macadam is superior because it is cheaper, faster, and its principle of a dry subgrade carrying load remains fundamental today. ## Answer Both are early-19th-century methods of road construction. **Telford** (Thomas Telford, 1757-1834) used a heavy stone foundation; **Macadam** (John McAdam, 1756-1836) used compacted broken stone laid directly on the subgrade. #### Sketches ```text Telford section Macadam section ~~ 40 mm wearing coat ~~~~ ~~ 50 mm top: 20-25 mm stone ~~ == 100 mm broken stone === == 100 mm layer: 50 mm stone == == 100 mm broken stone === == 100 mm layer: 50 mm stone == ## hand-set foundation ### ## stones 170-250 mm ##### ---- flat subgrade ------- ---- cambered subgrade (kept dry) ---- ``` (Typical thicknesses: Telford about 400-450 mm in total; Macadam about 250 mm.) #### Comparison | Basis | Telford | Macadam | |---|---|---| | Foundation | Large hand-packed stones, 170-250 mm | No special foundation; natural subgrade | | Thickness | About 400-450 mm | About 250 mm | | Subgrade | Flat (level) subgrade | Subgrade given a camber and drained | | Cost | High | Much lower | | Construction | Slow, needs skilled labour | Fast and simple | | Surface | Two layers of broken stone with a wearing coat | Angular stones compacted, binding with their own dust | | Principle | Load spread by a strong base | Load carried by a well-drained, dry subgrade | #### Why Macadam is superior - Needs much less material and labour, so it costs less. - Quicker to build and easier to repair. - Its principles (good drainage, camber, compacted angular aggregate) are still the basis of modern roads; Telford's heavy base is unnecessary when the subgrade is dry and well drained. - It was easily improved to bituminous macadam by adding tar or bitumen. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. How do the foundations of Telford and Macadam roads differ? A. Both use heavy hand-set stones B. Telford has no foundation; Macadam has heavy stones C. Telford has a hand-set stone foundation (170-250 mm); Macadam uses the natural subgrade D. Both use concrete Answer: C. Telford used large hand-packed stones; Macadam placed broken stones directly on the subgrade. (Key point: Foundation difference) 2. What are the approximate total thicknesses of Telford and Macadam roads? A. Telford about 250 mm, Macadam about 400-450 mm B. Both about 250 mm C. Both about 400 mm D. Telford about 400-450 mm, Macadam about 250 mm Answer: D. Telford is about 400-450 mm thick, Macadam about 250 mm. (Key point: Thickness comparison) 3. What is the principle of Macadam's design compared with Telford's? A. Load carried by well-drained, dry subgrade versus load spread by strong base B. Load carried by a heavy base versus by the subgrade C. Both rely on heavy bases D. Both rely on bitumen Answer: A. Macadam relies on a dry well-drained subgrade; Telford relies on a strong stone base. (Key point: Governing principle) 4. Why is Macadam construction considered superior? A. It is slower but stronger B. It needs less material and labour, is cheaper and quicker, and can be improved to bituminous macadam C. It needs skilled hand-setting D. It needs a thicker foundation Answer: B. It is cheaper, faster, easier to repair, and its principles underlie modern roads including bituminous macadam. (Key point: Why Macadam is superior) ## Related in Transportation Engineering I - [Macadam road construction method](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Amacadam-construction) — Transportation Engineering I, chapter 1 - [Short note: Telford construction](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Atelford-note) — Transportation Engineering I, chapter 1 - [Railway versus road transportation](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Arailway-vs-road) — Transportation Engineering I, chapter 1 ## Related in other subjects - [Water bound macadam materials and construction](https://www.bctengineer.com/question.md?key=semester_7%2Ftransportation_engineering_ii%3Awbm-construction-procedure) — Transportation Engineering II, chapter 3, asked 4× - [Auxiliary winding construction differs from main winding](https://www.bctengineer.com/question.md?key=semester_4%2Felectrical_machines%3Aaux-winding-construction-true-false) — Electrical Machines, chapter 7 - [Hill road earthwork with cross sections](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Ahill-road-u-cross-sections) — Estimating and Costing, chapter 6 - [Road construction equipment and mass haul characteristics](https://www.bctengineer.com/question.md?key=semester_7%2Ftransportation_engineering_ii%3Amass-haul-diagram-equipment-plants) — Transportation Engineering II, chapter 3, asked 3×