It’s National Roundabouts Week, and at Sain, we have plenty of reasons to celebrate.
Roundabouts have become an important part of our transportation work, helping communities address safety concerns, improve traffic flow, and navigate challenging intersection conditions. Around the office, you’ll often hear us shorten roundabout to “RAB.” Because we couldn’t let the week pass without having a little fun, we put our own musical spin on it. Check out our “RABs Easy as 1-2-3” video celebrating one of our favorite intersection types.
While our video may be lighthearted, the engineering behind a successful roundabout is anything but simple.
Why Roundabouts?
The Federal Highway Administration (FHWA) recognizes roundabouts as a Proven Safety Countermeasure. By reducing vehicle speeds and eliminating many of the conflict points found at traditional intersections, roundabouts can help reduce the frequency and severity of crashes. The FHWA reports that roundabouts reduce fatal and injury crashes by an average of 82 percent.
Roundabouts can also improve traffic flow, reduce delays, and accommodate a wide range of traffic conditions. Their flexibility is one reason Sain has evaluated and designed roundabouts for everything from local intersections to interstate interchanges.
Different Challenges, Different Roundabouts
Across Alabama, Sain has helped communities apply roundabout solutions to a variety of transportation needs.
Hayden Roundabout Series | Blount County, Alabama
At I-65 Exit 284 near Hayden, Sain designed a three-roundabout series at SR-160, US-31, and the interstate ramps. The project was developed in response to safety and operational concerns, including wrong-way movements onto the interstate. The design required careful consideration of interchange geometry, nearby businesses, and access to Park and Ride facilities.
Old Tuscaloosa Highway Turbo Roundabout | Jefferson County, Alabama
Growing industrial development and increased truck traffic created a different challenge along Old Tuscaloosa Highway in McCalla. Sain worked with Jefferson County to develop Alabama’s first, and the Nation’s third, turbo roundabout. Unlike a traditional multilane roundabout, the turbo configuration uses spiral geometry and raised channelization curbing to guide drivers through the intersection and prevent lane changes within the roundabout.
Sportsplex Parkway Roundabout | Opelika, Alabama
In Opelika, crash patterns at the intersection of Sportsplex Parkway and West Point Parkway prompted the City to evaluate improvement options. After reviewing traffic operations and several alternatives, a roundabout was selected to improve safety and traffic flow at this gateway to the Opelika Sportsplex and Aquatic Center. The project was completed in January 2023.
Cahaba Road Roundabouts | Birmingham and Mountain Brook, Alabama
Near the Birmingham Zoo and Birmingham Botanical Gardens, high traffic volumes, an awkward existing five-legged offset signal and adjacent developments required another approach. After evaluating several alternatives, the project incorporated a standard-sized modern roundabout paired with a mini-roundabout. The combination was designed to improve traffic flow while fitting within the limited space available in this busy corridor.
Finding the Right Fit
These projects demonstrate an important part of roundabout design: there is no single configuration that works everywhere. From a modular roundabout or compact mini-roundabout to a turbo roundabout or a series of roundabouts at an interstate interchange, each design must respond to the roadway, surrounding conditions, and the people who use it.
At Sain, we approach roundabouts as one of many tools available to address transportation safety and operations. Through thoughtful planning and engineering, we help communities evaluate their options and develop solutions that fit each location.
National Roundabouts Week is an opportunity to recognize how thoughtful design can improve the way people move through their communities, one intersection at a time. Have a transportation challenge of your own? Our Transportation Design team can help evaluate your options and develop solutions tailored to your community.