--- title: "Route location in hill road design" subject: "Transportation Engineering I" chapter: 5 key: "semester_6/transportation_engineering_i:hill-route-location" source: https://www.bctengineer.com/q/semester_6/transportation_engineering_i/hill-route-location site: BCT Engineering --- # Route location in hill road design Transportation Engineering I · Chapter 5: Hill Roads - Asked in: 2064 Shrawan (old course), 8 marks - Video: [U6L2- Alignment survey of hill roads](https://www.youtube.com/watch?v=YDCFkidd1ks) — GPC Online Learning - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_6/transportation_engineering_i/hill-route-location - Whole chapter: https://www.bctengineer.com/md/semester_6/transportation_engineering_i/chapter-5 ## Question Explain briefly about the route location in hill road design. ## Short answer Route location identifies control points, studies maps and aerial photos, and conducts ground reconnaissance. The alignment is chosen on stable, sunny slopes, with gradient near 5%, minimal stream crossings, balanced earthwork, and avoidance of unstable zones. Ridge, mid-slope or valley routes are compared for cost and stability. ## Answer Route location in hill roads is the process of choosing a stable, economical alignment between the fixed end points over difficult, steep and unstable terrain. #### Steps 1. **Identify control points** - the end points, mountain passes, saddles, bridge sites on rivers, settlements and market centres, and points to avoid (landslide zones, unstable slopes, forests, religious sites). 2. **Study of maps and photographs** - topographical maps, aerial photographs, satellite imagery and geological maps give possible routes. 3. **Reconnaissance** - walk the corridor to assess slope, geology, drainage, water sources and construction material. 4. **Selection of route** - the choice between a ridge, a mid-hill or a valley (river) route according to the following. | Route | Merit | Demerit | |---|---|---| | Ridge | stable, few drains | long, hard to serve villages | | Mid-slope | balanced and common | needs walls and cuts | | Valley | gentle gradient | flood, bank erosion, many tributary crossings | #### Main principles of hill road location - Prefer **sunny, stable and dry slopes**; avoid shaded, wet slopes. - Gradient near the ruling gradient (5%; limiting 6%); use hairpins only to gain height (spaced well, on stable ground). - Keep the **cross-drainage crossings** as few as possible and at the best sites (right angle to the flow). - Keep **cut and fill balanced** and the cutting height lower than the stability limit; avoid deep cuts and high fills. - Avoid **landslides, scree, rock falls, springs and unstable geology**. - Take **minimum land and environmental damage**, and keep the cost low for construction and maintenance. - Provide for **future widening** and stage construction (NRS 2070 recommends the engineering survey followed by a detailed geotechnical study). ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Which of the following is a control point to be AVOIDED when locating a hill road? A. A mountain pass or saddle B. A landslide zone or unstable slope C. A bridge site on a river D. A market centre Answer: B. Passes, bridge sites and settlements are points the route should pass through, while landslide zones and unstable slopes are points to avoid. (Key point: Control points) 2. What is the purpose of the reconnaissance step in route location? A. To fix the final cost of construction B. To walk the corridor and assess slope, geology, drainage, water sources and materials C. To prepare the working drawings of the walls D. To acquire the land Answer: B. Reconnaissance is a field walk-over that checks slope, geology, drainage and material availability along the possible routes. (Key point: Reconnaissance) 3. A valley (river) route is generally gentle in gradient, but what is its main demerit? A. It is very long and hard to serve villages B. It needs many retaining walls and cuts C. Flooding, bank erosion and many tributary crossings D. It has too many hairpin bends Answer: C. Valley routes have gentle grades but suffer from floods, bank erosion and many tributary crossings; the ridge route is the one that is long and hard to serve villages. (Key point: Ridge vs valley route) 4. Which is a correct principle of hill road location? A. Prefer shaded, wet slopes to keep the road cool B. Use deep cuts and high fills to keep a flat gradient C. Prefer sunny, stable and dry slopes with balanced cut and fill D. Use as many cross-drainage crossings as possible Answer: C. Sunny, stable, dry slopes are preferred, with cut and fill balanced and cross-drainage crossings kept few. (Key point: Principles of location) ## Related in Transportation Engineering I - [Special considerations in hill road design](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Ahill-special-considerations) — Transportation Engineering I, chapter 5, asked 5× - [Define hill road and design factors](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Ahill-define-factors) — Transportation Engineering I, chapter 5, asked 2× - [Structure of route location process](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Astructure-route-location) — Transportation Engineering I, chapter 2, asked 5× - [Principle and complexities of route location](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Alocation-principle-complexities) — Transportation Engineering I, chapter 2 - [River route location considerations](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Ariver-route-considerations) — Transportation Engineering I, chapter 5, asked 2× - [Hill road drainage structures](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Ahill-drainage-structures) — Transportation Engineering I, chapter 5, asked 4× ## Related in other subjects - [Hill road earthwork, 0+020 to 0+140](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Ahill-road-c-three-sections) — Estimating and Costing, chapter 6, asked 2× - [Hill road earthwork, 0 m to 90 m, 10/8 m widths](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Ahill-road-e-0-90) — Estimating and Costing, chapter 6, asked 2× - [Objectives of investigation for hill road](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aobjectives-of-investigation-for-hill) — Engineering Geology I, chapter 1 - [Hill road earthwork, chainage 130-280](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Ahill-road-formation-8-table-a) — Estimating and Costing, chapter 6