Despite a dramatic beam collapse last May, Mississippi Department of Transportation (MDOT) crews are looking to complete the $26.5 million U.S. 98 bridge replacement project in Franklin County by late summer or early fall.
"A temporary support structure failed during the erection of a girder segment over the river, causing other girder segments to fall," MDOT public information officer Anna Ehrgott told Construction Equipment Guide. "Fortunately, no one was hurt. An investigation into the cause was conducted, and crews paused work to implement necessary fixes. MDOT and the contractor worked together to ensure the safety of the project moving forward."
The fallen beams were removed from the project, and caps were repoured and new beams set. The collapse forced crews to carry out hydro-demolition, which uses highly pressurized water to precisely remove concrete while leaving steel intact. This method is faster and more efficient than operating jackhammers and creates a better bonding surface for repairs.
MDOT photo
The ongoing project is needed because the U.S. 98 bridge was nearing the end of its service life. Built in 1951, it was beginning to show signs of deterioration, and MDOT determined it was time to replace the bridge with a more modern post-tension structure that could better handle the demands of today's commuter and commercial traffic, featuring a design that's not typical for the region.
"Because truss bridges bear weight on both the top and bottom of the bridge, many truss bridges have height restrictions in place," said Ehrgott. "While these restrictions worked well for vehicular traffic in the past, today's commercial vehicles can exceed these limits, prompting rerouting, which sometimes results in lengthy detours.
"A modern post-tension concrete bridge will represent an important infrastructure upgrade for the citizens of Franklin County. The new bridge is not only bigger, stronger, wider and higher than the original, but the design also allows for longer spans between supports, which minimizes interference with the environment below and benefits marine traffic. Also, truss bridges include overhead, load-bearing bracings, which are susceptible to damage from over-height vehicles."
The bridge closed to traffic in November 2023. The first priorities for crews were constructing a work bridge, building new drainage structures and pouring trial shafts. Key LLC of Madison, Miss., a well-known local contractor, is overseeing the work.
"The company has the capacity to effectively fulfill contracts in a wide geographical region of the state," said Ehrgott. "It has performed quality work on many MDOT bridge projects in the past."
When asked by Construction Equipment Guide about the biggest concerns on the project, MDOT project engineer Dal Stell said, "Certainly, the beam collapse was a major setback, but field conditions at the site have also presented hardships. This area is prone to flash flooding, which presents drainage challenges and unsuitable materials."
According to Stell, substructure construction is complete, and work on the superstructure is progressing. Excavation and embankment operations are finished as well, with the exception of the construction of the spur dike along the north abutment of the river.
MDOT photo
Approximately 28,000 cu. yds. of onsite material is expected to be used on the project, with approximately 94,000 cu. yds. of embankment material placed. Sub-grade treatment consisted of soil-water-lime treatment and soil-water-cement treatment. This was based on the characteristics of the existing soil.
Stell said the final girder segment placements are complete as of March. The sections between the girders are cast with 6,000 psi concrete. Cables are being pulled through the girder segments, and the full length will be tensioned to form the 560 ft. continuous post tension span. With the post-tension span girders in place, the bridge deck and railings are being constructed.
Throughout construction, workers must be mindful of changing weather conditions. Stell noted that high, fast-moving and turbulent waters frequently affect the area after rainfall, affecting the contractor's access to work areas within and adjacent to the riverbanks. Crews must cope as best they can.
The contractor is using two 248 Link-Belt cranes for heavy lifting, and two smaller Link-Belt cranes for support operations. Multiple lifts, bulldozers, forklifts and excavators help maintain access throughout the site and move construction materials into place. These include pre-stressed beams, pre-stressed girder sections, concrete (Classes DS, AA and BD), reinforcing steel, steel cables for post-tensioning and local aggregate sources.
As for the original truss bridge, it had been deemed eligible for the National Register of Historic Places. In accordance with federal and state regulations, MDOT publicly offered the bridge to any organization or individual interested in relocating and maintaining the bridge prior to the replacement project letting. No one accepted the offer, forcing demolition.
Looking ahead to the new bridge, Stell said it's incredibly meaningful to be part of an effort that will serve so many for years to come.
MDOT photo
"This is likely the largest infrastructure project in Franklin County in a decade or more. The impact of this improvement will mean a safer commute for residents in the area, more efficient travel for commercial vehicles and a minimal environmental impact on the Homochitto River. Knowing that my children and grandchildren may drive over this bridge one day makes this project very important to me." CEG
