The population in Boone County, Kentucky, more than doubled over the last three decades and the steady growth isn’t stopping anytime soon. Located at the convergence of three major interstate systems and home to the Greater Cincinnati-Northern Kentucky International Airport, it’s easy to see why. However, the influx of residents has led to an increase in vehicular and non-vehicular traffic, and KY 237—a major roadway that serves as Boone County’s spine and connects neighborhoods and businesses—needed improvements to keep up.
The Kentucky Transportation Cabinet called on Gresham Smith to transform a 5.2-mile stretch of the curvy, two-lane roadway into an efficient corridor that reduces congestion, reconnects neighborhoods and accommodates alternative modes of transportation. Using a multi-lane roundabout, a single-point urban interchange (SPUI) and a multi-use path, the design team delivered a modern roadway that meets the needs of the growing Boone County community. The project was built in three phases, the last of which was completed in the summer of 2022.
reduction in traffic accidents
single-point urban interchange
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Taking the Process to the People
From the outset, Gresham Smith used a collaborative approach with the Kentucky Transportation Cabinet and maintained strong lines of communication with residents and businesses along the KY 237 corridor. Each public meeting had more than 300 attendees and one-on-one conversations with property owners helped establish priorities for the roadway project. The project team engaged a wide variety of stakeholders throughout the process because of the changing nature of the area. This included farmers, schools, churches as well as homeowners and renters.
A Win-Win Solution
Construction began on the south end of the corridor, which is bordered by Gunpowder Creek on one side and a church on the other. The design solution called for widening the existing roadway to five lanes and adding multi-use paths on both sides, which meant either the creek or the church would be affected. However, after much coordination, Gresham Smith recommended a retaining wall along the multi-use path and limited the impact to the church’s property. This section of KY 237 was the final project in Kentucky to be funded by the American Recovery and Reinvestment Act (ARRA).
A Single Point Solution
The second phase of the project addressed the intersection of KY 237 and KY 18 at the north end of the corridor. Traffic data initially indicated that KY 237 needed three left-turn lanes onto KY 18 to accommodate turning vehicles. However, the project team ultimately recommended a SPUI instead. By bringing all turning traffic to one elevated signalized intersection and allowing non-turning traffic to flow freely below, the SPUI limited the number of light cycles drivers sit through, freed up surrounding land and accommodated future traffic projections.
One Roundabout, Multiple Benefits
The final phase of the project, which connected the previously constructed sections, includes a new three-span bridge over Gunpowder Creek and a multi-lane roundabout at the intersection of KY 237 and Camp Ernst Road. The project team initially considered adding dual left-turn lanes at the existing “T” intersection, but later decided that a multi-lane roundabout would improve traffic flow and safety as well as shorten the construction limits along Camp Ernst road without the need for extended turn lanes and tapers. By eliminating many of the conflict points associated with conventional signalized intersections, roundabouts have been found to reduce the number of injury crashes.
Value Added
The KY 237 corridor required a palette of creative design solutions. Amidst the rolling terrain, alternating between farmland, large single-family residential developments and commercial nodes, the changing constraints of the corridor required a flexible design approach to create a pedestrian-friendly nexus between the pockets of development and provide a roadmap for the likely future development to come. Added value came from completing pedestrian connections to adjacent neighborhoods with closed loop sidewalk networks. Before zoning requirements, developers had little incentive to connect their sidewalks to a two-lane rural highway.
Addressing Drainage
As the corridor crosses Gunpowder Creek, South Fork Gunpowder Creek and many of the South Fork’s tributaries, the project required a significant investment in drainage, including construction of a three-sided structure, a box culvert, a three-span bridge and a single-span bridge widening as well as several large diameter crossing pipes. Because of the rolling terrain, the project corridor crosses multiple watersheds. The project team looked at opportunities to enhance stormwater management where possible. Through coordination with Sanitation District #1 and KYTC, several sites were chosen for the team to design detention basins, taking advantage of remnant parcels where possible. The ponds were sized to reduce post-construction peak discharge to pre-construction levels or better.
Connecting the Dots
The Gresham Smith project team went the extra mile to support community connectivity. The project provides a safer route to the local middle school, adds multi-modal access to Boone Woods Park and increases accessibility for nearby businesses. In fact, since the reopening of the first two sections of the project, the corridor has seen a significant decrease in crashes—about 39 percent. The new SPUI, multi-use path and forthcoming roundabout strengthen the backbone of Boone County and will support the growing community for years to come.Gallery
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