| 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
References
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