What is a mini-roundabout?
A mini-roundabout is a type of intersection that can be used at physically-constrained locations in place of stopcontrolled or signalized intersections to help improve safety problems and reduce excessive delays at minor approaches
[1]. Figure 1 illustrates the design features of a mini-roundabout; these features are described further later in this
summary. Mini-roundabouts generally have an inscribed circle that is small enough to stay within the existing right-ofway (or within the existing curb lines if adequate space is available). Mini-roundabouts operate in the same manner as
larger roundabouts, with yield control on all entries and counterclockwise circulation around a mountable (traversable)
central island.
Mini-roundabouts are distinguished from neighborhood traffic circles primarily by their traversable islands and yield
control on all approaches, which allows them to function as other roundabouts do. Neighborhood traffic circles are
typically built at the intersections of local streets for reasons of traffic calming and/or aesthetics. They typically are
operated as two-way or all-way stop-controlled intersections and frequently do not include raised channelization to
guide approaching traffic into the circulatory roadway. At some neighborhood traffic circles, left-turning vehicles must
turn in front of the central island, potentially conflicting with other circulating traffic.
To help promote safe operations, the design of mini-roundabouts generally aligns passenger cars on the approach in
such a way as to naturally follow the circulatory roadway and minimize running over the central island to the extent
possible. Due to the small footprint, large vehicles are typically required to over-run the fully traversable central island
(as shown in Figure 1).
Figure 1: Design Features of a Mini-Roundabout
How do I drive through a mini-roundabout?
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As you approach a roundabout there will be a Crosswalk sign and a YIELD sign and dashed yield limit line. Slow
down, watch for pedestrians and bicyclists, and be prepared to stop if necessary.
When you enter, yield to circulating traffic on the left, but do not stop if the way is clear.
Upon passing the street prior to your exit, turn on your right turn signal and watch for pedestrians and bicyclists
as you exit. There is a crosswalk at each leg of the roundabout.
Left turns are completed by traveling around the central island. If you have a large vehicle (vehicle pulling a
trailer, semi, fire truck, motorhome, etc…) you may need to travel over the center island to complete a left turn.
Considerations for different user groups?
Motorists
As with other types of roundabouts, mini-roundabouts calm traffic speeds and enhance the safety for drivers, including
older drivers, by:
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Allowing more time to make decisions, act, and react;
Reducing the number of directions in which a driver needs to watch for conflicting traffic; and
Reducing the need to judge gaps in fast traffic accurately.
Pedestrians
Pedestrians are accommodated at pedestrian crosswalks around the perimeter of the mini-roundabout. The splitter
islands at mini-roundabouts provide refuge for pedestrians, allowing them to cross the street one direction at a time.
Bicycles
Mini-roundabouts are generally located in environments where bicyclists are comfortable negotiating the roundabout as
a motor vehicle. In the event a bicyclist desires to navigate the intersection as a pedestrian, sidewalks and crosswalks are
provided.
The existing bicycle lanes will terminate before the roundabout and bicyclists riding on the road can travel through the
roundabout as a motor vehicle (and take the lane) or ride onto the sidewalks and cross at a crosswalk. Ramps will be
provided for bike access to and from the sidewalks.
Emergency Vehicles
Because of the traversable design of the central island and splitter islands, emergency vehicles are unlikely to have
significant difficulty negotiating a mini-roundabout.
What are the benefits of a mini-roundabout?
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Improve traffic flow through intersection
Reduce speeds
Yield in one direction only
Splitter islands for pedestrians
Snow removal considerations
Snow will be pushed through the roundabouts and carried onto the streets where it will be deposited in the middle of
the road per standard City operations. The splitter islands will only be cleared of snow when needed. The center island
will only be cleared as needed if the snow discourages passage of large vehicles that need to track over the center for
left turns. The pedestrian crossings will be cleared.
Learn more about mini-roundabouts at the following link:
http://www.youtube.com/watch?v=Mr3QAKszLag