Jefferson City’s roundabout system explained.

Roundabouts may still feel new to Jefferson City, even though we have had them for many years now. Modern roundabouts have been a traffic design tool for more than 50 years — they’re mostly used in Europe, but the roundabout found its way to the U.S. in the early 1990s and was first met with resistance and confusion. However, just like we’ve experienced here in Jefferson City, over time folks learned how they work and came to appreciate them — and even like them.

The decision to build a roundabout at an intersection is not made on a whim. There are various professional standards and guidelines that advise decision makers on when and where to construct a roundabout, especially when modifying an existing intersection.

First, a roundabout likely has to fit into an overall transportation plan, which identifies various road improvements that could be made if funds are available. Planning is critical because resources are limited, and it’s easier to make decisions when there is a prioritized plan for guidance. Jefferson City has long-term plans to address known transportation issues. If state or federal dollars become available, then the city doesn’t have to start from scratch to get a project off the ground. For example, one corridor in our community that included long-term planning is Stadium Boulevard. Over the years, the city, county, and state have invested resources to improve the corridor one project at a time.

Second, it’s important to determine if there’s a safety issue that needs to be addressed by a roundabout. For years, the intersection at Jefferson Street and Stadium Boulevard was a major concern. On a weekday mornings during the school year, it was common for traffic to be backed up onto Highway 54. This was a safety concern due to the curve in the highway shortly before the Jefferson Street exit. 

Third, data is critical to understanding what corrective measures should be taken to address the issue. Staff will collect information on a particular intersection, including traffic counts, crash data, peak times, and much more. Staff members evaluate this data and use professional guidelines to help determine what the appropriate improvement would be for that intersection. There will also be projections made about crash data based on what modifications are made to the intersection. For instance, traffic signals and stop signs may actually lead to more crashes since cars will start and stop more. In contrast, roundabouts may see fewer crashes because traffic continues to flow through the intersection.

Fourth, cost must be addressed. Major modifications come with a price, and not just an immediate one — traffic signals have more long-term costs to maintain the lights, for example. Projections are made to determine which option is the most cost-effective over time.

Finally, a decision is made by the governmental bodies overseeing the project. For many projects, the city and county partner together. At times, state transportation funds are used as well, and approval is required from a number of bodies before those projects can proceed. At the decision point, elected officials have to make a decision based on the information provided and input from affected individuals. Installing a roundabout can be a major disruption to an intersection during construction, and there will also be an adjustment period as folks become accustomed. This all falls under the decision makers’ consideration.

In my experience, the usual concerns are related to two categories: cost and construction and lack of familiarity. Any major public project takes these into consideration and weighs the overall benefits of the intersection improvement against potential impacts on private citizens or businesses. 

A couple of years ago, I was asked why there needed to be a roundabout on Jefferson Street and Stadium Boulevard. Someone commented that there didn’t seem to be much traffic, and it was rare to see any congestion. I responded that this was proof the roundabout worked. It addressed the initial safety concerns and traffic congestion so that traffic flows through smoothly.

It’s a very thorough process to make major modifications to an intersection. With finite resources, governmental bodies have to be efficient where improvements are made. The roundabout has proven to be a great improvement in our community, and I suspect we will continue to see more of them where it makes sense.