Federal Highway Administration's Roundabouts: An Informational Guide
The table of contents for Roundabouts: An Informational Guide is shown below. The guide includes a list of currently available resources used to create the guide, including existing design guides and other existing literature.
Chapter 1 - Introduction
This chapter defines roundabouts and establish the context for designing roundabouts in the U.S. The chapter draws a distinction between roundabouts and other circular intersections such as rotaries and neighborhood traffic circles. This chapter also presents six categories of roundabouts that are discussed in detail throughout the remainder of the document.
- 1.1 Scope of Guide
- 1.2 Organization of Guide
- 1.3 Defining Physical Features
- 1.4 Key Dimensions
- 1.5 Distinguishing Roundabouts from Other Circular Intersections
- 1.6 Roundabout Categories
- 1.7 References
Chapter 2 - Characteristics
This chapter provides a broad overview of the performance characteristics of roundabouts. The chapter discusses the costs associated with roundabouts versus other forms of intersections, legal issues, and public involvement techniques.
- 2.1 Characteristics
- 2.2 Multimodal Considerations
- 2.3 Costs Associated with Roundabouts
- 2.4 Legal Considerations
- 2.5 Public Involvement
- 2.6 Education
- 2.7 References
Chapter 3 - Planning
This chapter discusses general guidelines for identifying appropriate intersection control options, given daily traffic volumes, and procedures for evaluating the feasibility of a roundabout at a given location. Chapters 2 and 3 provide sufficient detail to enable a transportation planner to decide under which circumstances roundabouts are likely to be appropriate, and how they compare to alternatives at a specific location.
- 3.1 Planning Steps
- 3.2 Consideration of Context
- 3.3 Number of Entry Lanes
- 3.4 Selection Categories
- 3.5 Comparing Operational Performance of Alternative Intersection Types
- 3.6 Space Requirements
- 3.7 Economic Evaluation
- 3.8 References
Chapter 4 - Operational Analysis
This chapter presents methods for analyzing the operational performance of each category of roundabout in terms of capacity, delay, and queuing.
- 4.1 Traffic Operation at Roundabouts
- 4.2 Data Requirements
- 4.3 Capacity
- 4.4 Performance Analysis
- 4.5 Computer Software for Roundabouts
- 4.6 References
Chapter 5 - Safety
This chapter discusses the expected safety performance of roundabouts.
- 5.1 Introduction
- 5.2 Conflicts
- 5.3 Crash Statistics
- 5.4 Crash Prediction Models
- 5.5 References
Chapter 6 - Geometric Design
This chapter presents specific geometric design principles for roundabouts. The chapter then discusses each design element in detail, along with appropriate parameters to use for each type of roundabout. The chapter makes frequent reference to the AASHTO Policy and other key U.S. and international documents.
- 6.1 Introduction
- 6.2 General Design Principles
- 6.3 Geometric Elements
- 6.4 Double-Lane Roundabouts
- 6.5 Rural Roundabouts
- 6.6 Mini-Roundabouts
- 6.7 References
Chapter 7 - Traffic Design and Landscaping
This chapter discusses a number of traffic design aspects for consideration once the basic geometric design has been established. These include signs, pavement markings, and illumination. In addition, the chapter provides a discussion on traffic maintenance during construction and landscaping.
- 7.1 Signing
- 7.2 Pavement Markings
- 7.3 Illumination
- 7.4 Work Zone Traffic Control
- 7.5 Landscaping
- 7.6 References
Chapter 8 - System Considerations
This chapter discusses specific issues and treatments that may arise from how a roundabout fits into an existing transportation system. The material may be of interest to transportation planners as well as operations and design engineers.
- 8.1 Traffic Signals at Roundabouts
- 8.2 At-Grade Rail Crossings
- 8.3 Closely Spaced Roundabouts
- 8.4 Roundabout Interchanges
- 8.5 Roundabouts in an Arterial Network
- 8.6 Microscopic Simulation
- 8.7 References