On May 11, 2021, a partial fracture of the steel tie-girder box section was discovered during a routine visual inspection of the Hernando DeSoto Bridge, which carries I-40 over the Mississippi River between West Memphis, Ark., and Memphis, Tenn. Upon discovery of the fracture by inspectors from Michael Baker International, Arkansas and Tennessee Department of Transportation (ADOT and TDOT) officials closed the bridge to vehicular traffic, and river vessel traffic below the bridge was restricted by the U.S. Coast Guard. The bridge, which opened in 1973, carries approximately 60,000 vehicles a day.
The main portion of the bridge over the Mississippi River consists of a continuous two-span steel tied-arch truss; each span is 900 ft long. The tie-girder box beam is comprised of four Grade 100 steel plates with 32-in. by 1⅜-in. web plates and 25-in. by ½-in. top and bottom flange plates, and the fracture impacted 100% of the outboard web plate, 100% of the top flange plate, and approximately 20% of the bottom flange. The steel type used in the tie-girder box-beam, commonly referred to as “T-1” steel, is no longer used in modern-day bridge applications. It should be further noted that the Hernando DeSoto Bridge was designed and constructed well before the material and fabrication requirements of the AASHTO/AWS Fracture Control Plan were adopted by the industry in 1978.
Tennessee DOT is leading ongoing repair efforts, with Michael Baker International developing the repair design plans. On May 14, 2021, the Coast Guard was able to lift the waterway restriction based on information provided by the Tennessee DOT. A two-phased approach has been established where Phase 1 repairs will stabilize the bridge and allow for the use of equipment needed to install the permanent Phase 2 repair.
While uncovering a critical finding like the one on the I-40 bridge is never a good day, the steel industry responded with deliberate speed, efficiency, and safety by developing and fabricating repairs that can be quickly implemented on this steel structure, allowing the bridge to open back up safely.
- On May 17, Kiewit Infrastructure Group was awarded the emergency bridge repair contract and began mobilizing their equipment to the project site on May 19.
- Phase 1 steel repair fabrication began shortly thereafter at AISC certified member fabricator Stupp Bridge Company’s shop in Bowling Green, Ky., which included nearly 33,000 pounds of steel material.
- On May 22, TDOT crews picked up the repair material and delivered it to the bridge site. Kiewit Infrastructure Group worked 24-hour shifts installing fabricated steel plates on each side of the fractured member to secure the bridge, and completed the Phase 1 repair on May 25, 14 days after the discovery of the fracture.
The development of Phase 2 repair is currently underway, with expected delivery of the steel to occur by the end of June. As noted in the June 4 TDOT update, the Phase 2 repairs include nearly 53 tons of steel plate and 3,000 bolts. Permanent repair work will begin immediately upon arrival of the repair plate to the bridge site and is anticipated to go through July.