Roundabouts

​KYTC Roundabout Design Guidance
A modern roundabout is an alternative form of intersection control to traffic signals and multi-way stop control intersections. Therefore, roundabouts may be considered only when these intersection control types are warranted. The investigation of the need for a roundabout shall include an analysis of factors related to the existing operation and safety at the study location and the potential to improve these conditions.

​​FHWA Modern Roundabouts Video
Every year, more than 7,000 people are killed and nearly 1 million people are injured in intersection-related-crashes.
FHWA Modern Roundabouts - Large file

KYTC Roundabout Video
The Kentucky Transportation Cabinet presents Driving Modern Roundabouts.
KYTC Roundabouts

KY Public Informational Brochure
A modern roundabout is an unsignalized one-way circular intersection engineered to maximize safety and minimize traffic delay. Modern roundabouts can range in diameter from 45-200 feet with operating speeds typically ranging from 15-25 mph. Modern roundabouts are not traffic circles, rotaries, or neighborhood traffic calming circles.
Modern Roundabouts 101

Using a Single Lane and Multi-Lane Roundabout Brochure
The purpose of a roundabout is to reduce speed and increase safety.  However, that does not mean that they cannot be difficult to know how to enter and where to exit.  When you add roundabouts that are either single lane or multi-lane it can get overwhelming.  This brochure will hopefully serve as a reference to help you through the process of how to safely enter and exit no matter the type of roundabout.

Roundabout Brochure

​MUTCD Roundabout Markings
Roundabouts are becoming an increasingly utilized form of intersection design and control. To address the need for improved guidelines for marking roundabouts, the Markings Technical Committee has developed a new chapter, Roundabout Markings, for Part 3. The new chapter includes text and figures that should be useful to practitioners designing pavement markings at single- and multi-lane roundabouts.
MUTCD Roundabout Markings

Insurance Institute for Highway Safety
Traffic congestion and motor vehicle crashes are widespread problems, especially in urban areas. Roundabouts, used in place of stop signs and traffic signals, are a type of circular intersection that can significantly improve traffic flow and safety. Where roundabouts have been installed, motor vehicle crashes have declined by about 40 percent, and those involving injuries have been reduced by about 80 percent.
Insurance Institute for Highway Safety

National Roundabout Inventory
This web site serves as one of the definitive sources on Modern Roundabouts and is a complement to the Federal Highway Administration's research project aimed at developing a comprehensive guide to roundabouts design. Roundabouts are a common form of intersection control used throughout the world. However, many state and local agencies throughout the United States have been hesitant to install roundabouts due to a lack of objective nationwide guidelines on planning, performance, and design.
National Roundabout Inventory

FHWA Roundabouts: An Informational Guide
The modern roundabout was developed in the United Kingdom to rectify problems associated with these traffic circles. In 1966, the United Kingdom adopted a mandatory "give-way" rule at all circular intersections, which required entering traffic to give way, or yield, to circulating traffic. This rule prevented circular intersection from locking up, by not allowing vehicles to enter the intersection until there were sufficient gaps in circulating traffic.
FHWA Roundabouts: An Informational Guide

Roundabouts USA
This site is dedicated to free traffic flow through the design and use of roundabouts. This roundabout site is provided to people interested in learning more about roundabouts: what they are, where they are currently located, how effective they are, and how they operate.
Roundabouts USA

TRB Roundabout Conference 2005
Issues examined during the conference included the range of settings where roundabouts may be used, design elements and criteria, and methods of estimating safety and operations impacts. The conference also explored alternatives analysis; experience and practice; evaluation, design and completion; signs, paint, illumination, and landscaping, accommodations for pedestrians; modeling; and more.
TRB Roundabout Conference 2005

NCHRP 572: Roundabouts in the U.S.
This report summarizes the findings of NCHRP 3-65, "Applying Roundabouts in the United States." The intended audience for this report is researchers, practitioners, and policy makers who establish federal, state, and local guidelines for roundabouts. Although the content of this document is directly relevant to practitioners, the document is not organized as a guide for easy practitioner use.
NCHRP 572: Roundabouts in the U.S.

​Alaska
Alaska is a growing state - as it grows, their roads become more crowded and traffic delays build, which can result in frustration for Alaskan drivers, pedestrians, and bicyclists. A major role of the owners of the roads and public rights-of-way is to find solutions to crowded streets and traffic bottlenecks - solutions that are forward-thinking, cost-effective and improve driving, walking and biking conditions.
Alaska

California
Roundabouts are circular intersections that feature, among other important geometric components, a central island, a circulatory roadway, and splitter islands on approach. The use of modern roundabouts in the United States began in the early 1990's, and their popularity has continued to grow. This Design Information Bulletin is intended to provide assistance in ensuring their proper use on the State Highway system.
California

Kansas
This guide is a supplement to the Federal Highway Administration (FHWA) document "Roundabouts: An Informational Guide". This guide is intended to provide some consistent information regarding the planning, design, construction and operation of roundabouts in Kansas. Roundabout design is not a specific science, but more of an art form within the context of State and Federal guidelines.
Kansas

Maryland
Traffic circles have been part of the transportation system in the United States since 1905, when the Columbus Circle designed by William Phelps Eno opened in New York City. Subsequently, many large circles or rotaries were built in the United States. The prevailing designs enabled high-speed merging and weaving of vehicles.
Maryland

New York
This site serves to introduce and inform the public about the modern roundabout. A variety of topics are covered such as: what are roundabouts, how roundabouts differ from traffic circles and rotaries, how to properly use a roundabout, as well as the many benefits they provide.
New York

Oregon
ODOT, local jurisdictions and consultants are looking for alternative intersection control methods and roundabouts have been proposed as a solution. The Department has recognized the need for additional knowledge in the design and operation of roundabouts. To better evaluate the potential of this form of intersection control, ODOT began a research effort in July, 1997.
Oregon

Virginia
Roundabouts are one of the safest types of intersections designs. The Virginia Department of Transportation (VDOT) employs roundabouts to increase safety and reduce delays at intersections. Roundabouts also help reduce: crashes, traffic delays, fuel consumption, air pollution, construction and maintenance costs.
Virginia

Washington
Roundabouts are designed to make intersections safer and more efficient for drivers, pedestrians and cyclists. There are two types of roundabouts: single-lane roundabouts and multi-lane roundabouts. There are a few key things to remember about driving roundabouts: yield to drivers in the roundabout; stay in your lane; do not change lanes; do not stop in the roundabout; avoid driving next to oversize vehicles.
Washington

Wisconsin

2+1 Roads