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What is a roundabout?

A roundabout is a one-way, circular intersection in which traffic flows around a central island. Roundabouts require all entering traffic to yield to traffic already in the circle. The circular intersections have inherent geometric features that ensure slower entering and circulating speeds and provide:
•Reduced traffic delays
•Safety improvements
•Operational improvements
•Aesthetic enhancements

What are the different types of roundabouts?

Single-lane roundabouts reduce vehicle speeds in and around the roundabout.
Multilane roundabouts include signs and pavement markings to direct drivers into the appropriate lanes.
Modern roundabouts create a lower-speed environment and have been shown to provide a number of safety, operational and other benefits when compared to other types of intersections. There are no traffic signals or stop signs in a modern roundabout. Drivers yield at entry to traffic in the roundabout, then enter the intersection and exit at their desired street.

How many roundabouts are in Illinois?

The Illinois Department of Transportation has constructed 25 roundabouts on the state's highway system as of February 2023. The breakdown of how many roundabouts existing in each district is:

  • D1 – 8
  • D2 – 1
  • D3 – 1
  • D4 – 0
  • D5 – 0
  • D6 – 0
  • D7 – 0
  • D8 – 11
  • D9 - 4

The number of roundabouts in Illinois is much higher when you count those constructed by municipalities. More roundabouts are currently being planned by IDOT.

Who has the right of way in a roundabout?

Here are a few simple rules:
1. Pedestrians and bicyclists crossing the street always have the right of way. All motorists must yield to them before entering the intersection.
2. Traffic already moving inside the roundabout has the right of way. Yield to all motorists within the roundabout before entering.
3. If you’re entering the roundabout at the same time as another vehicle, the vehicle who arrives first should go first. However, drivers should always yield to any traffic that is approaching from the left. Once traffic from the left has cleared, drivers may proceed to enter the roundabout.

How do pedestrians cross a roundabout?

In a roundabout, pedestrians walk on sidewalks around the perimeter of the circular roadway. If they need to cross the roadway, they cross only one direction of traffic at a time. In addition, crossing distances are relatively short, and vehicle speeds tend to be lower.

How do bicyclists ride through a roundabout?

People on bicycles can choose to ride through the roundabout with traffic or walk their bicycles through the pedestrian crosswalks much like they would in a traditional intersection. Like motorists, bicyclists must obey the rules of the roundabout as they proceed through the intersection. Cyclists who choose to walk their bicycles may find that some roundabout designs have a ramp onto the sidewalk, which makes it easier for them to use.

Is it illegal to go around a roundabout more than once?

Circling a roundabout more than twice is careless driving. You should plan ahead as you enter a roundabout and carefully exit at the desired street.

Can you change lanes in a roundabout?

Only in certain instances. In a multi-lane roundabout, if the white line between lanes is dashed, you may change lanes with caution. If the white line is solid, changing lanes is prohibited. To change lanes, check your mirrors and potential blind spots before signaling your intention with your blinker.

How can roundabouts aesthetically enhance the community?

Roundabouts may be used in a variety of ways to enhance the aesthetics of the community. The centers of roundabouts may contain statues, flowerbeds or other visual elements as desired.

When are roundabouts the preferred choice to install over traffic-controlled light intersections?

Several key factors are considered. First, the traffic volume composition has to be amenable for a roundabout to function properly. If there is too much traffic in one or more directions, it will hold up the other leg(s) of the intersection, since roundabouts operate with gaps provided by traffic flow.

Second, the intended location must have sufficient room to enable proper design. If the location does not allow for the proper size of the circulating road or the approaches, the roundabout will not function as safely or efficiently as it should.

Can roundabouts accommodate large commercial vehicles?

Yes. A truck apron is a raised concrete area near the roundabout's center that provides extra space for larger vehicles to turn and maneuver.