--- title: "At-grade intersection requirements; street lighting importance" subject: "Transportation Engineering II" chapter: 1 key: "semester_7/transportation_engineering_ii:intersection-requirements-street-lighting-importance" source: https://www.bctengineer.com/q/semester_7/transportation_engineering_ii/intersection-requirements-street-lighting-importance site: BCT Engineering --- # At-grade intersection requirements; street lighting importance Transportation Engineering II · Chapter 1: Traffic Engineering - Asked in: 2075 Asoj, 8 marks - Video: [What is Intersection ? Types of intersection || And the Requirement of Intersection .](https://www.youtube.com/watch?v=C09131jeH5Y) — Engineering Podium - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_7/transportation_engineering_ii/intersection-requirements-street-lighting-importance - Whole chapter: https://www.bctengineer.com/md/semester_7/transportation_engineering_ii/chapter-1 ## Question What are the basic requirements of intersection at grade? Mention the importance of street lighting. ## Short answer Basic requirements: safety with clear sight triangles, adequate capacity, simple layout, minimum conflict area, good visibility, channelization, proper control devices, and pedestrian facilities. Street lighting improves night visibility, reduces crashes, increases safety and capacity, enhances personal security, and guides drivers. ## Answer #### Basic requirements of an intersection at grade 1. **Safety first:** reduce the number and severity of conflict points; give drivers clear sight of each other (sight triangle, IRC:66 and IRC:SP:41). 2. **Adequate capacity:** the junction must carry the design hour volume of all movements without long delays. 3. **Simple, clear layout:** drivers should understand the movements at once; avoid complex or multiple-road junctions; avoid skew (angle between roads should be about 90 degrees, not less than 60 degrees). 4. **Minimum conflict area:** keep the paved area small and channelise movements with islands, so vehicles cannot wander. 5. **Good visibility:** approach sight distance and sight triangles should be free of obstructions. 6. **Separation of conflicts** by space (islands, channelisation), by time (signals) or by level (grade separation). 7. **Suitable geometry:** correct approach gradients (flat, not more than about 4 percent), corner radii for the design vehicle, adequate turning lanes and pedestrian facilities. 8. **Proper traffic control devices:** signs, markings, signals or rotary where needed. 9. **Pedestrians and cyclists** need crossings, refuge and signal time. 10. **Economy:** the cost of land, construction and operation should match the benefit. 11. **Drainage and lighting** for safe all-weather and night use. #### Importance of street lighting - It **improves night visibility** so that drivers see the road, obstacles, pedestrians and other vehicles in time to stop. - It **reduces crashes** and the severity of crashes at intersections, curves, bridges, and pedestrian crossings. - It **improves personal security** and reduces crime in urban areas. - It **increases the capacity and speed** of the road after dark by raising the confidence of the driver. - It **helps traffic flow and the economic life** of commercial areas (night shopping, tourism). - It **gives guidance** to the driver on road alignment, junctions and the edge of the pavement, and it enhances the look of the city. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Which is a basic safety requirement of an at-grade intersection? A. Maximise paved area B. Reduce number and severity of conflict points with clear sight C. Use many legs D. Allow steep approach gradients Answer: B. Safety first: fewer conflict points and clear sight triangles. (Key point: Conflict reduction) 2. What approach gradient limit is suggested? A. Flat, not more than about 4 percent B. Up to 15 percent C. Exactly 0 percent D. At least 6 percent Answer: A. Approaches should be flat, not more than about 4 percent. (Key point: Approach gradient) 3. How is the conflict area kept small? A. Wider paved area B. Keep paved area small and channelise with islands C. Remove markings D. Add more arms Answer: B. Islands channelise movements so vehicles cannot wander over a large area. (Key point: Minimum conflict area) 4. Why does street lighting reduce crashes? A. It improves night visibility so drivers see hazards in time to stop B. It reduces traffic volume C. It slows vehicles by law D. It replaces signs Answer: A. Better night visibility gives time to see obstacles and pedestrians and stop. (Key point: Importance of lighting) ## Related in Transportation Engineering II - [At-grade intersection requirements and night visibility](https://www.bctengineer.com/question.md?key=semester_7%2Ftransportation_engineering_ii%3Aintersection-requirements-night-visibility-lighting) — Transportation Engineering II, chapter 1 - [At-grade intersection requirements; rotary design steps](https://www.bctengineer.com/question.md?key=semester_7%2Ftransportation_engineering_ii%3Aintersection-requirements-rotary-design-steps) — Transportation Engineering II, chapter 1 - [At-grade requirements; grade separated intersection](https://www.bctengineer.com/question.md?key=semester_7%2Ftransportation_engineering_ii%3Aintersection-requirements-grade-separated) — Transportation Engineering II, chapter 1 - [Street lighting importance and design factors](https://www.bctengineer.com/question.md?key=semester_7%2Ftransportation_engineering_ii%3Astreet-lighting-importance-design-factors) — Transportation Engineering II, chapter 1 - [Intersection types; grade separation pros and cons](https://www.bctengineer.com/question.md?key=semester_7%2Ftransportation_engineering_ii%3Aintersection-types-grade-separated-advantages) — Transportation Engineering II, chapter 1 - [Grade separation types; conflict points](https://www.bctengineer.com/question.md?key=semester_7%2Ftransportation_engineering_ii%3Agrade-separation-types-conflict-points) — Transportation Engineering II, chapter 1 ## Related in other subjects - [Outdoor lighting purposes and street lighting](https://www.bctengineer.com/question.md?key=semester_6%2Findustrial_power_distribution_and_illumination%3Aoutdoor-lighting-street-methods) — Industrial Power Distribution and Illumination, chapter 8, asked 2× - [Factors for street and flood lighting design](https://www.bctengineer.com/question.md?key=semester_6%2Findustrial_power_distribution_and_illumination%3Aflood-street-design-factors) — Industrial Power Distribution and Illumination, chapter 8, asked 2× - [Street lighting principles and flood design](https://www.bctengineer.com/question.md?key=semester_6%2Findustrial_power_distribution_and_illumination%3Adiffusion-specular-flood-procedure) — Industrial Power Distribution and Illumination, chapter 8 - [Street lighting a 2 km road with sodium lamps](https://www.bctengineer.com/question.md?key=semester_6%2Findustrial_power_distribution_and_illumination%3Astreet-lighting-sodium-2km) — Industrial Power Distribution and Illumination, chapter 8