--- title: "Urban road networks and ring road" subject: "Transportation Engineering I" chapter: 1 key: "semester_6/transportation_engineering_i:urban-network-ring-road" source: https://www.bctengineer.com/q/semester_6/transportation_engineering_i/urban-network-ring-road site: BCT Engineering --- # Urban road networks and ring road Transportation Engineering I · Chapter 1: Introduction to Transportation Planning and engineering - Asked in: 2063 Kartik (old course), 4+4 marks; 2062 Jestha (old course), 8 marks (asked 2 times) - Video: [Urban road system](https://www.youtube.com/watch?v=uj82f6rS0a0) — Rahul Patel - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_6/transportation_engineering_i/urban-network-ring-road - Whole chapter: https://www.bctengineer.com/md/semester_6/transportation_engineering_i/chapter-1 ## Question Explain briefly the various forms of urban road network system with neat sketches. How does the provision of a ring road help to minimise congestion in the city core areas? ## Short answer Urban networks include grid-iron, radial, radial-circular, hexagonal, linear, and irregular forms. A ring road reduces city-core congestion by diverting through traffic and linking radial roads outside the central area, cutting vehicles, noise, and pollution in the centre, and improving suburban access. ## Answer #### Forms of urban road network **1. Grid-iron (rectangular):** parallel roads cross at right angles. ```text | | | | --+---+---+---+-- | | | | --+---+---+---+-- ``` Simple and flexible, but many conflict points and long diagonal trips. **2. Radial (star):** roads spread from the central business district (CBD) like spokes. ```text \ | / ---- O ---- / | \ ``` Gives direct access to the centre but causes congestion there. **3. Radial-circular (ring-radial):** radials joined by one or more ring roads. ```text .-----------. / \ | / \ | ---- O ---- | \ / | \ / '-----------' ``` **4. Hexagonal:** three-way junctions only; fewer conflicts but difficult to set out. **5. Linear (ribbon):** development along one main axis (e.g. a highway or river). **6. Irregular/organic:** grows with the terrain and history, as in old Kathmandu valley towns. #### How a ring road reduces congestion in the city core A ring road is a circumferential road around the city that connects the radial roads outside the central area. 1. **Diverts through traffic:** vehicles which only pass the city (trucks, inter-city buses) use the ring instead of entering the core. 2. **Links radial roads** directly, so traffic going from one suburb to another need not pass through the centre. 3. **Reduces vehicles, noise and pollution** in the CBD and gives space for pedestrians and public transport. 4. **Improves access** to the outskirts and helps controlled development of the city fringe. 5. **Gives a high-speed alternative route** and reduces travel time and accidents. 6. **Helps freight movement:** heavy vehicles can be restricted in the centre in day time. Example: the Kathmandu Ring Road (about 27 km) carries traffic around the old city and the core. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What is the weakness of the grid-iron network? A. Cannot be extended B. Only three-way junctions C. Many conflict points and long diagonal trips D. No parallel roads Answer: C. Grid-iron is simple and flexible but has many conflict points and long diagonal trips. (Key point: Grid-iron features) 2. A ring road is best described as which of the following? A. A road leading into the CBD B. A circumferential road around the city connecting radial roads outside the central area C. A road along a river D. A road with only three-way junctions Answer: B. A ring road circles the city and links radial roads outside the core. (Key point: What a ring road is) 3. How does a ring road reduce congestion in the city core? A. By forcing all traffic through the centre B. By removing radial roads C. By diverting through traffic such as trucks and inter-city buses away from the core D. By adding parking in the CBD Answer: C. Through vehicles use the ring instead of entering the core, reducing vehicles, noise and pollution there. (Key point: Diverting through traffic) 4. Why does a ring road help traffic between two suburbs? A. It links radial roads directly so traffic need not pass through the centre B. It makes the trip pass through the CBD C. It closes suburban roads D. It reduces road speed Answer: A. Linking radials outside the centre lets suburb-to-suburb trips bypass the core. (Key point: Linking suburbs) ## Related in Transportation Engineering I - [Major urban road patterns](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Aurban-road-patterns) — Transportation Engineering I, chapter 1, asked 5× - [Urban road cross-section elements](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Aurban-road-cross-section) — Transportation Engineering I, chapter 3, 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 - [Network congestion and its parameters](https://www.bctengineer.com/question.md?key=semester_7%2Fcomputer_networks_and_security%3Anetwork-congestion-parameters) — Computer Networks and Security, chapter 5 - [Underground feeder economical in urban areas](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Ajustify-underground-urban-economical) — Transmission and Distribution System Design, chapter 5, asked 4× - [Wind pressure on 36 m building, core city](https://www.bctengineer.com/question.md?key=semester_6%2Fdesign_of_steel_and_timber_structure%3Awind-core-city-36m) — Design of Steel and Timber Structure, chapter 8, asked 3× - [Quality control in urban road construction](https://www.bctengineer.com/question.md?key=semester_7%2Fproject_engineering%3Aquality-control-urban-roads) — Project Engineering, chapter 4