---
title: "Channelized intersections: advantages and disadvantages"
subject: "Transportation Engineering II"
chapter: 1
key: "semester_7/transportation_engineering_ii:channelized-intersections-pros-cons"
source: https://www.bctengineer.com/q/semester_7/transportation_engineering_ii/channelized-intersections-pros-cons
site: BCT Engineering
---

# Channelized intersections: advantages and disadvantages

Transportation Engineering II · Chapter 1: Traffic Engineering

- Asked in: 2070 Chaitra, 8 marks
- Video: [3.7.2 Advantages of Channelized Intersections | CE502 |](https://www.youtube.com/watch?v=tqnicKjIeN8) — RGPV Official
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/transportation_engineering_ii/channelized-intersections-pros-cons
- Whole chapter: https://www.bctengineer.com/md/semester_7/transportation_engineering_ii/chapter-1

## Question

Describe channelized intersections with their advantages and disadvantages.

## Short answer

Channelized intersections use raised or painted islands to guide vehicles into defined paths, separating conflicts. Advantages: fewer and less severe crashes, higher capacity, free turns, pedestrian refuge. Disadvantages: higher cost, island hazards if unlit, tight for large vehicles, and may confuse drivers.

## Answer

A **channelised intersection** is an at-grade junction in which traffic movements are guided into definite paths by raised or painted islands, kerbs and markings, so that conflicts are separated and the paved area is reduced (IRC:SP:41).

```text
        |  |  |
        |  |  |  <- splitter island
   _____|  |  |_____
  /     \  \  /     \
 ---  triangular      ---
  \_____/ island \_____/
        |  |  |
```

#### How it works
- Islands (triangular, divisional, refuge) force vehicles into turning or through lanes.
- Turning roadways with large radius give free left turns (for left-hand traffic), so those vehicles do not wait for the signal.
- Markings, signs and signals work together with the islands.

#### Advantages
- Reduces the number and severity of conflicts, so crashes fall.
- Separates movements and fixes the vehicle path, so there is less confusion and wrong-way driving.
- Reduces the large paved area, which limits vehicle wandering and speed.
- Provides refuge for pedestrians and a place for signs, signals and lighting.
- Increases capacity (free turns, separate turn lanes) and reduces delay.
- Gives control of speed and angle of merging; allows protected turning lanes.

#### Disadvantages
- Higher cost of construction and kerbs, and more land for turning roadways.
- Islands are hazards if poorly marked or lit, especially at night; vehicles may hit them.
- Hard for large vehicles to turn if radii or lane widths are too small.
- Too much channelisation can confuse drivers and block snow or debris clearing, and complicates future widening.
- Long walking distance for pedestrians if they must cross many lanes.

## Check yourself

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

1. What defines a channelised intersection?
   A. Grade-separated junction with ramps
   B. At-grade junction where islands, kerbs and markings guide movements into definite paths
   C. Junction controlled only by traffic police
   D. Circular junction with one-way flow around a central island
   Answer: B. Channelisation uses raised or painted islands, kerbs and markings to separate conflicts and guide vehicles. (Key point: Definition)

2. How do turning roadways with large radius help?
   A. They force left-turners to wait for the signal
   B. They give free left turns so those vehicles do not wait for the signal
   C. They remove all pedestrians
   D. They increase paved area
   Answer: B. Free turns separate turning traffic and raise capacity while reducing delay. (Key point: Free turns)

3. Why does reducing the large paved area improve safety?
   A. It limits vehicle wandering and speed
   B. It lets vehicles overtake freely
   C. It removes the need for signs
   D. It increases turning radii
   Answer: A. A smaller paved area restricts wandering and keeps speeds and conflict angles under control. (Key point: Reduced paved area)

4. Which is a disadvantage of channelised intersections?
   A. More conflicts between vehicles
   B. Islands are hazards if poorly marked or lit, especially at night
   C. Pedestrians have no refuge
   D. Capacity always falls
   Answer: B. Poorly marked or unlit islands can be hit by vehicles, and construction cost and land requirement also rise. (Key point: Disadvantage of islands)