The rumble of traffic on the Interstate-40 Mississippi River bridge in Memphis has been replaced by staccato bursts of drills and bolt tensioners as workers with Kiewit Infrastructure Group race to stabilize a fractured tie girder that forced an indefinite closure of the key Tennessee-Arkansas crossing on May 11.
The 24-hour effort, which began May 21, is the first part of a two-phase repair strategy being carried out by the Tennessee Dept. of Transportation (TDOT). It shares maintenance responsibilities with the Arkansas Dept. of Transportation (ARDOT). Working from a 100-ft platform suspended from one of the two 900-ft-long, tied-arch spans some 110 ft above the river, crews are adding more than 33,000 lb of steel plating to the 24 x 32-in. tie-girder’s 1.375-in.-thick top and bottom sections, and .5-in.-thick side sections.
“From a repair standpoint, the first thing was to look at the bridge and see if it’s safe for traffic underneath,” as well as for repair crews, says Paul Degges, TDOT deputy commissioner and chief engineer. Workers are bolstering the girder with a 54-ft-long, 2.5-in.-thick outer plate and a slightly shorter inner plate. The plates will restore sufficient stability for the arch to support heavy equipment necessary for second-phase repairs, which may include installation of high-strength steel rods so that the 37-ft-long section can be replaced.
No cost or timeline have been announced for the repairs, which are being procured under TDOT’s emergency contracting authority. “We are finishing design on the new box beams,” says Degges. “It will take a minimum of six to eight weeks, but we hope to solidify the timeframe once drawings are complete.”
Michael Baker International (MBI), ARDOT’s inspection consultant, alerted the agency to the fracture during a routine survey of the nearly 50-year-old crossing. MBI is the Engineer-of-Record with input from TDOT, ArDOT, and Kiewit Infrastructure Group.
What remains to be determined is the origin of the fracture, which ARDOT says is likely a “fatigue-type” break that resulted from decades of constant traffic, rather than a vessel impact or weather-related cause. Emergency inspections of the bridge have revealed no other structural concerns.
Details have emerged regarding the now-terminated ARDOT inspector who failed to report the fracture.
Monty Frazier, a 15-year ARDOT employee, was team leader and under-bridge inspection unit operator for the annual fracture-critical inspections conducted in September 2019 and 2020. Frazier reported no issues with the continuous welded beams that form the structure’s 110-ft-high navigation spans, but drone video from a May 2019 inspection by MBI indicated the break had begun to form.
By the time ARDOT officials were alerted on May 11, the tie-girder’s upper and outer flanges had separated, while the bottom flange was approximately 50% cracked. The bridge, which has about 41,000 daily crossings, was immediately closed.
According to ARDOT documents released through a public records request by the Hot Springs, Ark., Village Voice newspaper, Frazier told Michael Hall, the agency’s heavy bridge maintenance engineer, that it was “unsafe” to move the under-bridge inspection unit along the outside of the tie girder.
Hall refuted Frazier’s claim in a May 14 termination memo, stating that “standard practice is to boom out along the tie girder, looking for cracks.” He also noted that Frazier had done this himself when another employee had controlled the under-bridge unit, which is equipped with “safety features that keep one from moving into an unstable position.”
ARDOT announced the termination May 17 without mentioning Frazier by name, stating that “the employee failed to carry out his responsibility correctly,” and could possibly face criminal charges. ARDOT is reviewing inspections led by Frazier of at least nine other bridges, as well as its inspection practices.