My Roundabout Can Beat Up Your Roundabout!



Decklan Group Economic Development Consultant Roundabout

Roundabouts… they’re like the “White Castles” of the transportation world; it seems like people either love them or they hate them. But why does this particular traffic control device generate such a strong reaction from people? You generally don’t hear impassioned speeches about traffic signals, or see online discussion posts debating the pros and cons of four-way stop signs.

Back when I was in college nearly two decades ago, I was doing research for a paper for one of my transportation planning classes. In the course of my research, I found an interesting article from another couple decades prior that had been published in the St. Cloud Times. The article was about a proposed intersection improvement that involved something previous not seen in Central Minnesota. It was deemed unsafe and confusing; opponents were sure it would cause more crashes, injuries and deaths. You know what they were talking about? A left turn signal.

The thing with roundabouts is that they’re new, they’re different, and they take a little getting used to. Some folks have difficulty navigating them. And that can make some people uncomfortable driving, walking or biking through them. Thus leading to some lively debates about this new traffic control device, officially known as a “modern roundabout.”

Modern roundabouts – different than traffic circles in that they’re smaller and drivers yield upon entry – are great in the right circumstances, but they're not appropriate everywhere. They're simply one more tool in the toolbox - just like a traffic signal or a 4-way stop.

There are several benefits that roundabouts can bring to our transportation network, and there are some negatives as well…

Roundabouts are FAR safer than conventional intersections. According to MnDOT, roundabout have shown nearly a 90% reduction in fatal crashes, nearly 75% reduction in serious injury crashes, and nearly 40% reduction in crashes overall. When crashes do occur, they tend to be less severe due to the “deflection” – the angle at which you approach the intersection. So from a traffic safety perspective, they're not such a bad deal.

When I first heard that MnDOT was considering installing roundabouts in the state, I was skeptical. But the safety numbers they presented from previous studies in other parts of the country were enough to convince me that it was worth a shot.

Another benefit of roundabouts is that they keep traffic moving, reducing emissions from cars idling at red lights or stop signs. MnDOT has estimated the reduction to be about 30%, which can be substantial in some urban areas.

They can also work well for skewed or off-set intersections – all of us have driven through intersections that force us to crane our necks in an un-natural fashion to check for cross traffic. In some of those cases, a roundabout would make that situation a little easier to deal with.

One common misperception of roundabouts is that semi trucks cannot navigate them. Besides those of us who work in the planning and engineering fields, the concept of the “truck apron” is typically unheard of. The center of the roundabout should (if properly designed – and not all are) have a relatively flat paved area (often concrete) that’s on a raised curb. This area, known as the truck apron, is designed for the back tires of the semi to roll up and over, allowing them to navigate the roundabout, while still providing an appropriate radius to keep automobile traffic moving through at a safe speed.

For more info, check out MnDOT’s roundabouts web site: http://www.dot.state.mn.us/roundabouts/

That said, there are places that are appropriate for roundabout installation, and places that are not. Roundabouts may not be the best choice for intersections that have significant grades or slopes on the approaches; heavy traffic on one approach vs. others; frequent oversize vehicles; and near railroad crossings. When improvements are considered, engineers will evaluate each intersection to determine the best traffic control device. That’s true for roundabouts, signals and four-way stops.

Once folks become comfortable driving in roundabouts, it'll be second nature, and you won't see as many people doing the unpredictable things you commonly see now. Very few people today think twice about left turn signals, and the same will be true of roundabouts in a few years.

This blog was written for Decklan Group by Wayne T. Hurley, AICP


Wayne T. Hurley, AICP, is the Planning Director for West Central Initiative (WCI), a regional foundation that serves nine counties in west central Minnesota. Wayne began work as WCI’s transportation planner in 1998.  He is currently responsible for supervising all of WCI’s planning activities, including the transportation planning, economic development, active transportation planning and GIS programs. 

Wayne graduated with Honors from St. Cloud State University in St. Cloud, Minnesota with a Bachelors degree in Local and Urban Affairs. He is certified as a professional planner though the American Institute of Certified Planners.

In addition to his duties at WCI, Wayne serves on the boards of directors for the Minnesota Chapter of the American Planning Association and the Otter Tail County Historical Society. He is also a member of the City Council in Fergus Falls, Minnesota, and previously served on the city’s Planning Commission and Heritage Preservation Commission.

Wayne lives in Fergus Falls with his wife and their two daughters.