While not suitable for all situations, roundabouts are being used in CSS projects because they can offer several advantages over conventional intersections: they eliminate conflict points, while increasing vehicle capacity; they reduce delay and costs of site acquisition and signal maintenance; they can be very attractive and become a community focal point; and they have a terrific safety record.
Modern Roundabouts - NYSDOT (opens in a new window)
This website was developed by the NYS DOT as an introduction to roundabouts, covering topics such as: what are roundabouts, how roundabouts differ from traffic circles and rotaries, how to properly use a roundabout, and the many benefits that roundabouts provide. It is meant to keep the public and consultants informed on where roundabouts are in operation and development throughout New York State. The site also includes guidance for roundabout design.
Broad Street Roundabout Position Paper
The paper describes the circumstances supporting the final decisions for design and construction of a roundabout on Broad Street in Nashua, New Hampshire. It also describes operational conditions that have been recorded since completion of the roundabout.
-- Eric M. Teitelman P.E.
Towson Roundabout Towson, MD
Towson, Maryland is a suburb of Baltimore, Maryland. Near the central part of the Towson business district, four major arterials converge at a single location. The awkward, multi-leg signalized intersection caused congestion and safety problems. In addition, the business community and City of Towson sought improvements to the economic viability of the downtown and believed that economic improvements were directly related to traffic improvements. A number of alternatives were developed, and eventually, a signalized roundabout, relatively new to the U.S. at the time, emerged as the preferred solution. The roundabout and streetscape project are considered a major success and are a source of local pride in the town of Towson.
Little Rock Roundabout - Arkansas Little Rock, AR
With the widening of W. 36th Street residents were concerned about higher traffic speeds. Some residents wanted speed humps installed. At the time a signalized intersection at W. 36th and Romine was not justified on traffic counts. The roundabout was proposed by city traffic engineers, but was neither initially endorsed by neighborhood community nor considered by the project design engineers of Little Rock Public Works. There were two public meetings held, the first to discuss the nature of the improvements and right-of-way requirements for West 36th Street and the second focused on the intersection at W. 36th Street and Romine. An extensive presentation on roundabouts, with graphic support including a video, was given at the second public meeting. In a memorandum to the City Manager the Cityﾒs Traffic Engineering Manager stated the pros and cons of the options and the results of the poll of the second meetingﾒs participants. He recommended the roundabout as a solution to the concerns of the citizens about speeding on the improved W. 36th Street (speed humps were deemed inappropriate for an arterial).
Mount Rainier, MD, Neighborhood Conservation Project Mount Rainier, MD
US Route 1 (Rhode Island Avenue) split the commercia of traffic with an ADT of 21,000. This division created numerous transportationl town center of Mount Rainier with a six-legged intersection and four lanes and urban design problems that hindered commercial revitalization in the heart of the community. The basic issues were pedestrian safety; environmental enhancement; the Washington Metro Area Transit Authority bus turn-around area (with 8 routes and 1,352 passengers daily); storm drainage inadequacy; the lack of a clean, safe, and welcoming mixed-use town center; and vehicular and bicycle safety. This project replaced a six-legged intersection and four lanes of cars rushing through two blocks of liquor stores and abandoned buildings with a simple traffic roundabout, landscaped plazas, pedestrian lighting, easy pedestrian crossings, bus shelters built on early 20th-century designs, new business, and with public art including two blue-glass sculptures that will be lit at night at opposite ends of the roundabout and bas relief sculptures of some of the diverse faces that make up the community of Mount Rainier.
Highway through Arnage, France Arnage,
"In Arnage, a suburb of Le Mans, the heavily trafficked main street has been rebuilt in order to improve both traffic safety and the quality of the urban environment."
Roundabout in Vamdrup, Denmark Vamdrup,
"In Vamdrup an intersection of 5 roads has been converted into a beautiful and well-functioning roundabout which not only solved a traffic problem, but also created a town space that is important for civic well-being."
US 395 Roundabout - Colville Roundabout Colville, WA
U.S. 395 is a major arterial and north/south international freight corridor, which follows Main Street through Colville. In partnership with the City of Colville, WSDOT coordinated the design and funding of its programmed U.S. 395 improvements including upgraded signals, widening, and paving with the Colville 2000 revitalization strategy for Main Street. Revitalization elements on Main Street included pedestrian sidewalk and safety improvements, enhanced historic-style illumination, and city center landscaping.
"The term 'modern roundabout' is used in the United States to differentiate modern roundabouts from nonconforming traffic circles or rotaries that have been in use for many years. Modern roundabouts are defined by two basic operational and design principles: Yield at entry, and Deflection of Entering Traffic."