A roundabout is a circular intersection where traffic flows around a center island. Roundabouts are safe, efficient and less costly. Since vehicles entering the roundabout are required to yield to traffic in the circle, more vehicles can move through the intersection with less delay. The unique one-way design of roundabouts also accommodates the turning radius of large vehicles, like semi-trucks and buses.
How to drive a roundabout
Watch a video on how to drive in a multi-lane roundabout.
As a driver approaches a roundabout, there will be a YIELD sign. The driver should slow down, watch for pedestrians and bicyclists and be prepared to stop if necessary.
When the driver enters, he/she yields to circulating traffic on the left, but does not stop if the way is clear.
The roundabout will have ONE WAY signs mounted in the center island. They help guide traffic and indicate that the driver must stay to the right of the center island.
Upon passing the street prior to the desired exit, the driver should turn on his/her right turn signal and watch for pedestrians and bicyclists as he/she exits.
Traveling around the central island completes left turns.
Driving a Multi-lane roundabout
Get in the correct lane early. Observe pavement markings and signs (For example: Use the right lane to turn at the first right or go straight. Use the left lane to go straight, make a left turn, or make a U-turn).
Give large trucks (with long trailers) room to take up both lanes as they approach, circulate and exit the roundabout.
Yield to ALL traffic already in the roundabout, even if you're only entering the right lane (or outside lane) of the roundabout.
Never pass or change lanes in the roundabout.
When exiting from the inside lane, check the lane next to you and your blind spot to make sure the outside lane is clear. Use your turn signal to let other drivers know that you are exiting.
Graphic illustration depicting traffic flow through a roundabout on State Route 203 near Duvall
The elements that constitute a roundabout are:
- Yielded entry – cars entering must wait for a gap in the circulating traffic before entering the roundabout
- Islands separate the entry from the circular roadway
- Designated crossing area for pedestrians
- Designed to be driven at speeds of 15 – 20 miles per hour
- Single or multiple lanes
Roundabouts are not traffic circles or traffic calming islands
A roundabout is not the same as the older-style rotary traffic circle like those found in some East Coast and European cities. The main difference between older style traffic circles and roundabouts is in how traffic enters the circle and which vehicle has the right-of-way. With roundabouts, drivers wishing to enter must yield to vehicles already in the circle. With many of the older traffic circles, drivers inside the circle must yield to the vehicles entering the circle. Traffic circles quickly clogged up and came to a standstill when and if many vehicles entered at the same time.
Aerial view of an older traffic circle.
Roundabouts also differ from traffic calming islands in several ways. These small traffic circles are often used to slow traffic speeds in residential neighborhoods and reduce accidents. In addition, the raised center islands are not designed to accommodate large vehicles and left-turning traffic, which often take the turn in front of the circles.
A local neighborhood traffic calming island.
Roundabouts are designed to accommodate all types of traffic
Large trucks
Roundabouts are designed to handle fire trucks, buses and various sizes of emergency vehicles, as well as truck and trailer combinations. The center island of all single-lane roundabouts is built with a gradually sloped and flat curb, called a truck apron. This apron makes it easier for long vehicles to make the turns as demonstrated in the photo below:
Truck and trailer combination moving through a roundabout with rear wheels
crossing over the truck apron.
Where there are multiple lanes of entry and two or more lanes of circulating traffic, the roundabout is designed with the idea that trucks will use both lanes to travel through the roundabout as smoothly as possible. A truck approaching a roundabout may straddle both lanes, similar to making a “wide right turn” at a standard intersection, provided the driver has determined it is safe to move into the adjacent lane and has signaled their intentions. When a driver of a car or small truck approaches a roundabout where a large truck has stopped to yield to circulating traffic, they should drop back behind the truck as it completes its movement through the roundabout and when exiting. The video clip below demonstrates the truck movement through a two-lane roundabout:
Semi truck moving through roundabout (Windows Media 758 kb)
Semi truck moving through roundabout (RealVideo 380 kb)
Pedestrians
Pedestrians may find traveling through a roundabout just as safe as through an intersection with a signal, if not safer. This is due to the fact that vehicles are moving at a slower rate of speed and pedestrians need only to cross one direction of traffic at a time. Cars are required to yield to pedestrians in the area marked for pedestrian crossings.
Photograph courtesy of Reid Middleton, Inc.
Bicycles
A bicyclist can travel through the roundabout as a pedestrian, or in the circular roadway with motorized vehicles. Bicyclists have the same rights and responsibilities as motorists when riding on the roadway. Inexperienced riders may choose to walk their bicycles and use the pedestrian crosswalks to get through the roundabout. Some roundabout designs have a ramp onto the sidewalk, which makes it easier for bicyclists to use.
Emergency Vehicles
When an emergency vehicle approaches an intersection, most drivers get out of the intersection as quickly as possible and pull to the side. A roundabout is really no different. If an emergency vehicle enters the roundabout with lights or sirens on while you are in the circle, continue to your intended exit and then pull over to the side of the road. If you are approaching a roundabout, pull over if there is room for the emergency vehicle to get by; otherwise, continue through the roundabout and pull over after you’ve exited the roundabout.
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