Although roundabouts have been increasingly common in the U.S. since the 1990s, Illinois has lagged behind its neighbors in implementing this proven concept. But now that’s changing — in part due to a project designed by Burns & McDonnell.
A new roundabout at the Kane County intersection of Burlington Road and Illinois Route 47 opened to traffic on Dec. 8. Here’s a look at how our team convinced the Kane County Division of Transportation (Kane DOT) and the Illinois Department of Transportation (IDOT) that a roundabout was the best solution for this busy intersection.
The Need for Improvements
The intersection, which is shared by Kane DOT and IDOT, is a heavily traveled stretch of highway west of the suburban Chicago frontier. An increase in crashes in the 1990s prompted Kane DOT to install a four-way stop. And while safety improved significantly, the four-way stop also created heavy congestion, especially during peak travel times. Kane DOT needed a solution that would improve traffic flow at the intersection.
Making the Case for a Roundabout
When Kane DOT turned to Burns & McDonnell for a design solution, a roundabout wasn’t even a consideration. Original plans considered a conventional traffic signal, but the resulting design’s wide expanses created nearly as many problems as it solved. It also came with a hefty price tag.
Our team was steadfast in seeking a solution that not only addressed the intersection’s pain points but was also cost-effective. A roundabout addressed both problems.
We were confident in our recommendation, but the relative novelty of roundabouts for this audience demanded that we lay out a strong case for a roundabout. Here’s how we demonstrated the advantages of a roundabout for this intersection:
Studies have shown that roundabouts are safer than conventional intersections controlled by signals or stop signs. Roundabouts require drivers to reduce their speed before entering. And since all traffic is moving in the same direction, it eliminates the need for right angles and left turns, reducing the potential for head-on collisions.
More Efficient Traffic Flow
Roundabouts reduce congestion by allowing traffic to flow more continuously at the intersection. Instead of coming to a complete stop or waiting for a signal to change, incoming drivers yield to traffic in the circle and merge where there’s a break, as seen in this simulation.
Our roundabout uses considerably less pavement than a conventional intersection. A signal would have required three entry lanes — one for each movement — but a roundabout requires only one. Reducing the impervious surface allows for shorter and shallower ditches and reduces runoff into adjacent farm fields by as much half.
The intersection’s location on the edge of a growth area meant that we needed to consider potential expansion. A traffic signal could not address additional capacity without another lane and even longer tapers. The roundabout is designed to add a second through lane on Illinois Route 47 without significant grading or staging.
A roundabout isn’t the right solution for every intersection — but it was for this one. It improved existing conditions, resolved issues posed by the traffic signal and saved $1 million — a significant savings that the agencies could get behind.
A First for Kane DOT and IDOT
When the roundabout opened, it marked a first for both Kane DOT and IDOT. It was Kane DOT’s first roundabout, and the first roundabout for IDOT District 1 on a Chicago-area Strategic Regional Arterial. It is already paving the way for new roundabouts for both agencies.
We’ll be checking in regularly with Kane DOT to see how the community adapts to the roundabout, and learning how we can improve future roundabouts. If you want to learn more about the Kane County roundabout, check out my LinkedIn Pulse article and download this case study.
Matt Papirnik is an associate traffic engineer in Burns & McDonnell’s Chicago office, specializing in highway design and intersection geometry. Matt served as the project manager for both the scoping phase and the detailed design phase of this roundabout.