Global Street Design Guide

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Table of Contents

Global Street Design Guide

Complex Intersection: Improving Traffic Circles

Existing Conditions

Many cities have large traffic circles with inaccessible central spaces, complex traffic patterns, and hazardous conditions for all users.

This illustration depicts a large roundabout in which seven streets enter at a number of angles, resulting in motorists entering the  roundabout at differing speeds and with variable sight lines. A confusing assembly of one- and two-way streets entering the  intersection creates a fast-moving, perplexing traffic pattern.

The large roundabout negates many of the benefits of a compact roundabout, such as managing speeds and reducing conflicts.

The wide central space is almost inaccessible to pedestrians. Unmarked, multiple travel lanes result in dangerous conditions for  vulnerable users. No cycle facilities are provided.

Cairo, Egypt

Design Guidance

The intersection is redesigned to facilitate better movement for all users, and to improve the usability, safety, and quality of the central open space.

Extend the central space and provide raised pedestrian crossings to ensure safe access while slowing vehicular traffic.

 Reduce the roundabout to two travel lanes, decreasing the number of conflicts and lane changes occurring in the circle.

Reconfigure street approaches to as close to 90-degree angles relative to the traffic circle as possible. Ensure all entering vehicles have clear sightlines to oncoming traffic of all modes, and stop or slow all entering vehicles.

Extend sidewalks and the central plaza, dedicating space to street vendors and other active uses. Add planting, trees, seating, lighting, and other street furniture to make the central space more attractive and functional.

 Clearly demarcate paths for cyclists throughout the intersection as various cycle facilities on adjacent streets meet the traffic circle. Install cycle lanes on the outside of the roundabout to reduce interaction with vehicles, and change marking pattern at points of potential conflict.

Fuentes de Cibeles; Mexico City, Mexico

Adapted by Global Street Design Guide published by Island Press.

Complex Intersection: Increasing Permeability

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Complex Intersection: Increasing Permeability