By CHRISTOPHER KNAPP

Construction on a bridge replacement project on Missouri Route 79, within the city limits of Hannibal, began earlier this year aimed to enhance safety, connectivity and infrastructure resilience in the area. The original structure built in 1967 and located in the heart of America’s Hometown, spans Bear Creek, Norfolk Southern Railroad and Warren Barrett Drive.

Many challenges arose through the planning process due to several contributing factors. The existing structure serves as a main connector to the city’s south side for tourists, residents and industry, including two large manufacturing facilities with significant commercial truck traffic. Close coordination with the city was necessary for logistical planning, traffic control and working through the right of way process.

A signed detour using state routes is in place, although residential traffic has utilized local streets due to the long detour extending several miles. Streets in this area are weight limited and unsuitable for truck traffic.

Located just a few blocks away from the Mississippi River, the bridge’s close proximity introduced weather and topography-related uncertainties, especially the possibility of spring flooding commonly experienced in the area. While delays to the construction schedule would be realized, most important were the potential impacts limiting the use of local streets for travel and emergency services. Advanced preparations included collaboration with local emergency management, including a tabletop exercise with local emergency service providers to determine solutions to best serve all customers impacted in various scenarios.

Furthermore, construction closed access to the Sodalis Nature Preserve within the project limits, affecting locations of various activities scheduled during the annual National Tom Sawyer Days, including the Hannibal Cannibal 5K/10K/15K race averaging 1,000 to 2,000 participants.

To minimize the duration of the Missouri Route 79 closure, the project was specifically designed to allow a significant amount of the substructure to be constructed while the existing bridge was still in use. A closure of 180 days was allotted to complete demolition and new build.

The new bridge will boast a minimum life expectancy of 75 years and have several improvements over the previous design, including a decrease in the maximum grade from 8 percent to 4.85 percent, a shorter length from 1,012 feet to 877 feet and a 10-foot-wide, fully ADA-compliant shared-use path to be enjoyed by pedestrians and cyclists where only a partial sidewalk and steps previously existed.

KCI Construction Company was awarded the contract in the amount of $12.4 million and is scheduled to complete the project this fall.

Christopher Knapp is a project manager with the Missouri Dept. of Transportation.