Enhancing Safety Along a High-Crash Corridor

Route 160 from Springfield to Willard serves a rapidly growing community in southwest Missouri. Due to the commercial and residential growth, there was a major strain on the roadway, leading to unsafe conditions for motorists.

The Missouri Department of Transportation (MoDOT) consulted CMT to complete planning and design to enhance safety in the region and provide infrastructure solutions for the budding community.

The project included capacity and safety improvements along six miles of Route 160 mainline by widening the existing two-lane highway to a four-lane divided section, facilitating pedestrian-friendly access to a nearby trail, and pioneering intersection geometric designs to significantly improve safety. Innovative design alternatives were explored at the nine intersections along the corridor to maintain access and provide enhanced safety benefits. Ultimately, three unique roundabouts, two J-Turn/RCUT locations, and one Continuous Green-T (CGT) intersection were implemented to reduce the number of signalized intersections and enhance intersection safety.

As a first-of-its-kind design in Missouri, CMT designed multi-lane turbo roundabouts to account for high approach speeds. This was accomplished by providing multi-stage curvature and extended splitter islands to reduce speeds, extending exterior curbs to improve headlight reflectance and curve recognition, and providing “bail-out” areas to allow inattentive drivers a safer place to come to a stop in a wide flat grass area outside of the roadway. This roundabout needed special consideration to simplify the design for newer drivers, improve intersection capacity, and provide safer intersection geometrics while accommodating access for existing and future development within the corridor.

The project team partnered with Missouri University of Science & Technology to facilitate a driving simulation research project to better understand the impacts of the new design and quantify how drivers would respond, allowing the team to identify potential concerns and refine final design based on the data. This research simulation was performed prior to construction to provide MoDOT with the most practical, cost-effective, and safety-enhanced design.

Since construction ended in late 2020, the corridor has seen a significant reduction in both crash occurrences and fatal or serious injury crashes compared to the pre-construction five-year average.