Roundabouts in southern Minnesota

By Joe Steck

Mankato and other southern Minnesota communities are adding roundabouts and they are here to stay.  Many in the area are now wondering why they are being put in and how does someone properly navigate through this circular intersection.

Why put in a roundabout and not traffic lights?  Efficiency is a big reason.  Roundabouts are typically more efficient than traffic signals. At roundabouts, vehicles can enter the circulating roadway whenever there is a suitable gap, most often without coming to a full stop. Additionally, vehicles can enter from multiple approaches simultaneously.  During off-peak traffic periods roundabouts excel, as there is no need to be stopped waiting for a green light.

Research in the U.S. and abroad has shown that roundabouts experience lower crash rates than both traffic signal and stop sign controlled intersections. The Insurance Institute for Highway Safety conducted a study of 24 intersections located throughout the U.S. where roundabouts replaced traffic signals or stop signs. This study found fatality and incapacitating injury crashes were reduced by 90%, injury crashes were reduced by 76% and overall crashes were reduced by 39%.  At roundabouts the geometric design features ensure that vehicle speeds are low, therefore, when collisions do occur the severity is typically nothing more than a fender-bender type crash.  T-bone accidents should be reduced greatly.

Cost benefits to a roundabout are no signal equipment to install and repair with a savings estimate on average of $5,000 per year in electricity and maintenance costs.  The service life of a roundabout is about 25 years vs. 10 years for traffic signals.  Stop signs are cheaper, but you do face the negative effects of safety issues mentioned above.

How will snow be removed?  Typically a snow plow truck will start on the inner most section of the circulating roadway, often on the truck apron and keep circulating in a spiral outward with each revolution until the whole circle is cleared. Either the same plow vehicle or a second plow vehicle will clear the snow from the approaches and exits.

If you are in a roundabout and an emergency vehicle approaches you should react similar to the way you would at any other location. If there is an opportunity to safely move to the side of the roadway you should do so. If you are in the circulating roadway and the emergency vehicle is following you, you should continue to your exit and move to the side as soon as possible. If you are in the circulating roadway and the emergency vehicle is on an approach you will be passing, stop and let the emergency vehicle enter into the roundabout, then continue on your way.


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