Klingner designed a roundabout for the City of Hannibal to replace an existing T-intersection on Shinn Lane. The intersection — which is surrounded by Hannibal Regional Hospital (HRH), a new hotel, and a gas station — frequently experienced congestion during peak travel times.
Klingner’s engineers conducted a traffic analysis and provided three intersection options with opinions of probable cost. A roundabout design was chosen due to the lower operational cost, existing sight geometrics, and aesthetics. A traffic control plan was also developed to maintain access to businesses during construction. Multiple meetings were held with stakeholders, including all businesses along the corridor. Project updates were sent biweekly and meetings were scheduled for every major change in traffic control.
Services provided include topographic and boundary surveys, Right-of-Way evaluations, preliminary and final design, environmental clearances, bidding assistance, and construction phase services. Traffic volumes are managed with a single lane roundabout and designated left turn lanes at business intersections. AutoTURN was used to design necessary turning radii for the appropriate truck traffic that is entering and leaving the roundabout. The roundabout was sized to properly connect existing businesses, accounting for HRH’s existing landscaping, the location of the Shell Station’s fuel storage tanks, and the new Holiday Inn Express and Suites that was being constructed. Sidewalks were relocated to allow safe pedestrian travel from the hospital and hotel to the gas station. Crosswalks were added to Shinn Lane, and concrete sidewalks were upgraded to be ADA compliant.
The project also included concrete pavement, concrete approaches, curb and gutter, segmented block wall, grading, stormwater inlets and pipes, landscaping, and erosion control. While some utilities were relocated, the roundabout was designed around an electrical pole, which proved cost-prohibitive to move.
The entire project was coordinated with the City of Hannibal and the Missouri Department of Transportation (MoDOT), and it was designed to MoDOT standards.