Roundabouts

Sources / References:
2011 AASHTO Green Book
NCHRP Report 672
“Accelerating Roundabouts in the United States: Volume IV of VII – A Review of Fatal and Severe Injury Crashes at Roundabouts.” Office of Safety. Federal Highway Administration. FHWA-SA-15-072. September 2015.

What Is Roundabout?
A circular, unsignalized intersection where all traffic moves counterclockwise around a central island
Traffic entering the roundabout slows down and yields to traffic already inside the roundabout
Roundabouts can be designed with one or more circulating lanes
Design options allow for right turns to be channelized to bypass the circulating lanes

When Should It Be Considered?
At intersections:
With heavy left-turn traffic or with similar traffic volumes on each leg
With crashes involving conflicting through and left-turn vehicles
With limited room for storing vehicles
Where there are limited nearby driveways

Benefits
Improved safety: Reduces the number of points where vehicles can cross paths and eliminates the potential for right-angle and head-on crashes.
Increased efficiency: Yield-controlled design means fewer stops, fewer delays and shorter queues
Safer speeds: Promotes lower vehicle speeds, giving drivers more time to react
Long-term cost effectiveness: No traffic signals means lower long-term costs for operations and maintenance
Aesthetics: Allows for landscaping and beautification

#HighwayDesign #Roundabout #DanielFindley