Frequently asked questions (FAQ)

Do roundabouts save lives?

Yes. The Insurance Institute for Highway Safety found roundabouts are safer for two main reasons:

  • Less potential for serious crashes (head-on and T-bone collisions are eliminated)
  • Low travel speeds (less severe crashes result from lower travel speeds)

The University of Wisconsin Traffic Operations and Safety (TOPS) Lab has analyzed roundabouts in Wisconsin. Specifically, the data has shown that converting two-way stop control intersections to single lane roundabouts decreases fatal and injury crashes by 51.9% and 58.2% in rural and urban areas, respectfully.

Do roundabouts reduce congestion?

Roundabouts can handle more traffic in the same amount of time because traffic is not required to stop – only yield. A study measuring traffic flow at intersections before and after conversion to roundabouts in Nevada, Kansas and Maryland found that traffic delays were reduced between 13% and 23%.

How much do roundabouts cost?

The construction costs of roundabouts and signalized intersections are generally comparable. Actual costs depend on site-specific conditions. The estimated construction cost of a roundabout can range from $500,000 to $3 million based on a number of factors (i.e., available right of way, traffic volumes, turning movements, large vehicle percentage, bicycle/pedestrian accommodations, etc.).

Are roundabouts the preferred WisDOT intersection design?

WisDOT does not have a preferred intersection design. Each intersection is unique and has its own place as part of the transportation system. WisDOT incorporates many factors when considering the appropriate traffic control at an intersection, including safety, operations, and user needs, among others. These factors are analyzed as part of WisDOT’s Intersection Control Evaluation (ICE) process.

Does public input influence roundabout consideration?

Public input is one of the factors considered in the ICE process. WisDOT believes in the importance of communicating early and frequently, especially on projects that contain features that may be new to the community. WisDOT staff meet with local officials, businesses, and community members to get input early – when a transportation concern is first identified – and throughout the design phases.

Is public opinion on roundabouts changing?

Research has shown that the number of people who favor roundabouts more than doubles as they gain experience with them. A survey by the Insurance Institute for Highway Safety showed that before construction, the number of drivers in favor of roundabouts was only 31% and those strongly opposed was 41%. Follow-up surveys after roundabout installation showed those in favor increased to 63% and those strongly opposed dropped to just 15%.

Are there environmental benefits from roundabouts?

While cars and trucks are increasingly cleaner and greener, vehicles idling at a signalized intersection still emit pollutants and gases into the atmosphere. Stops and starts use more fuel. Because roundabouts reduce the number and duration of stops, they also reduce vehicle emissions and fuel consumption.

How does WisDOT facilitate large vehicles travel through roundabouts?

WisDOT recognizes the importance of providing safe, efficient travel and accommodating the freight industry in delivering goods and services, as well as other large vehicles such as emergency vehicles, buses, and farm equipment. All roundabouts installed on the state highway network are designed to accommodate legal size trucks. Special design considerations are incorporated to accommodate oversize/overweight (OSOW) vehicles when a roundabout is located on a designated OSOW route.

What needs to be done to decrease the fender-bender crashes occurring at roundabouts?

Safely maneuvering in a roundabout requires drivers to be alert and follow three key rules:

  • Slow down!
  • Yield to all circulating lanes. Remember, circulating traffic has the right of way!
  • At multi-lane roundabouts, choose the correct lane before entering the roundabout

WisDOT provides outreach materials to local communities, including driver educators, to help motorists adjust to driving roundabouts. A video tutorial and other materials are available on WisDOT’s website, The Division of Motor Vehicle Motorists’ Handbook includes a special section with information on how to drive in a roundabout.