IDOT Roundabouts

What is a roundabout?

Modern roundabouts are becoming mainstream throughout Illinois. These circular intersections efficiently move traffic counterclockwise around a center island, offering safety, environmental and economic benefits to drivers and communities.

Not to be mistaken for traffic circles, which are often larger and include stop signs or traffic signals, modern roundabouts have yield signs at each entry point. Roundabouts are designed for lower-speed driving with all traffic moving in the same direction, eliminating left turns across traffic and creating fewer stress points that can cause crashes. An intersection’s traffic volume and size are a few factors considered when deciding a roundabout is the preferred choice over a traffic light-controlled option in a location.

Why consider a roundabout?

REDUCE CONFLICTS

Roundabouts reduce 32 conflict points from traditional intersections with traffic signals or stop signs, to only 8 conflict points, lowering chances of vehicle-to-vehicle crashes.

SAFER

Improves traffic safety Increases efficiency: Yield-controlled design typically means fewer stops, fewer delays and shorter queues Reduces the number of points where vehicles cross paths and eliminates the potential for right-angle and head-on crashes Lower vehicle speeds are generally safer for pedestrians Slower speeds give drivers more time to react

SAFER

Roundabouts are proven to be safer! Roundabouts require driving 25 mph or slower giving drivers more reaction time to other vehicles or pedestrians in crosswalks. Slower speeds reduce severe injury crashes.

EFFICIENT

Roundabouts are more efficient than traditional intersections!

Provide longer service life:

Roundabouts = 25-year service life
Signal equipment = 15-year service life
Eliminate wasted time spent at red lights during off-peak hours
Reduce carbon emissions and fuel consumption.

SAVINGS

Roundabouts cost less long-term than traditional traffic signal intersections!

Reduce road electricity and maintenance costs
Less expensive to operate than traditional intersections with traffic signals
Save communities money!

SAVINGS

Roundabouts cost less long-term than traditional traffic signal intersections!

Reduce road electricity and maintenance costs
Less expensive to operate than traditional intersections with traffic signals
Save communities money!

* “Safety Effect of Roundabout Conversions in the United States: Empirical Bayes Observational Before-After Study.” Transportation Research Record 1751, Transportation Research, National Academy of Sciences (NAS), Washington, D.C., 2001.

** NCHRP Report 572: Roundabouts in the United States. National Cooperative Highway Research Program, TRB, NAS, Washington, D.C., 2007.

Visit safety.fhwa.dot to learn more about roundabouts!

How to drive a roundabout

Yield when you approach a roundabout and watch for pedestrians in the crosswalk.
Look to the left as you near the dashed yield line and yield to traffic already in the circle.
Once you see a gap in traffic, enter the circle and proceed to your exit. Look for pedestrians as you exit and make sure you stay in your lane as you navigate the roundabout.
In a multi-lane roundabout, choose a lane before entering the roundabout. Signs posted near the roundabout will direct you to the appropriate lane based on whether you want to make a left turn, go straight or make a U-turn.
Choose either the left lane as you enter the roundabout or choose the right lane if you want to make a right turn.

Roundabout Locations

Roundabout Photos

FAQ

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 20 roundabouts on the state's highway system as of March 2021. The number of roundabouts in Illinois is much higher when you count municipalities, but for a state highway system, IDOT has 20 roundabouts. 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.