Geometric Design of Roundabouts

The Geometric Design of Roundabouts online PDH course is a part of the Civil Engineering category of courses.

Roundabouts are a common form of intersection control used throughout the world and increasingly in the United States. The course provides guidance on geometric planning and design, for single and multi-lane roundabouts.

Selection and design of a roundabout, as with any intersection treatment, requires the balancing of competing objectives. These range from transportation-oriented objectives like safety, operational performance, and accessibility for all users to other factors such as economics, land use, aesthetics, and environmental aspects. The course material allows enough flexibility to encourage independent designs and techniques tailored to particular situations while emphasizing performance-based evaluation of those designs.

Roundabouts operate most safely when their geometry forces traffic to enter and circulate at slow speeds. Poor roundabout geometry has been found to negatively impact roundabout operations by affecting driver lane choice and behavior through the roundabout. Many of the geometric parameters are governed by the maneuvering requirements of the design vehicle. Thus, designing a roundabout is a process of determining the optimal balance between safety provisions, operational performance, and accommodation of the design vehicle.

This course is intended for use by civil engineers, transport planners, project managers, construction professionals and others interested in learning about geometric properties of roundabouts.

This course is based on Chapter 6 “Geometric Design” of the National Cooperative Highway Research Program Report 672, “Roundabouts: An Informational Guide”.

Learning Objectives

At the end of the course, you will learn about:

• Principles of good roundabout design, including speed management, lane arrangement, sight distances, visibility and others
• Size, position and alignment of approaches
• Single-lane roundabouts: geometric design, entry and exit design
• Multilane roundabouts: geometric design, entry and exit design
• Mini roundabouts
• Design details such as pedestrian and bicycle consideration, parking and bus stop consideration, high-speed approaches and materials and design details
• Closely spaced roundabouts and interchanges
• Access management