Ultrasonic testing on more than 500 weld connections on the closed Interstate 40 bridge found nine locations that need steel plating for additional support, the Tennessee Department of Transportation said Tuesday.
The design of the plates is taking place and the material is being sourced, the department added in its twice-weekly update on the work to repair the Mississippi River crossing between West Memphis and Memphis. Fabrication of the plates will follow.
The update said the goal remained to reopen the bridge by the end of the month.
A draft report on the inspection performed by an outside firm, which the department received Friday, said no additional failures were found beyond the one discovered by chance during an unrelated inspection May 11.
According to the update, the contractor is "making significant progress" on the repairs related to the fracture found in May that affected the structural integrity of the span -- also called the Hernando De Soto Bridge -- including the installation of "all structural and splice plates ... at the fracture location."
The last of the eight plates needed to replace the fractured area was installed last week, the department said.
Work that is scheduled to take place this week includes minor drilling on small connection pieces, final bolting and torquing and de-stressing of the post-tensioning system, which should be completed by Saturday. Once the post-tensioning system is destressed, the removal of the post-tensioning rods and weldment/anchors will begin, the update said.
The bridge connecting Tennessee and Arkansas is a major commercial corridor. Traffic has been rerouted to the Interstate 55 bridge, 3 miles to the south.
The crack on the I-40 bridge, a tied-arch span, was found on a steel beam that connected cords to the arch. When the beam cracked, the load that was once carried by the beam shifted to other parts of the bridge.
The Tennessee Transportation Department oversees repairs of the I-40 bridge, while the Arkansas department is responsible for inspections. Kiewit Infrastructure Group of Omaha, Neb., was contracted for the repairs.
Work to repair the bridge has been going on 24 hours a day, seven days a week. The fractured section of the I-40 bridge's tie girder was removed June 21.
The way the bridge is designed means the Arkansas Department of Transportation classifies it as "fracture critical," meaning parts of the bridge are "subject to tension whose failure would probably cause a portion of or the entire bridge to collapse." Fracture critical bridges require frequent inspections but are not inherently unsafe.
The crack was discovered May 11, but a photo from 2019, confirmed by transportation officials to be authentic, shows the crack has been around potentially for years. Another photo appears to show a crack as far back as 2016, but the authenticity of that image remains under investigation.
The discovery led the Arkansas Department of Transportation to fire the inspection team leader for missing the crack during at least two previous inspections, which are conducted annually.
Traffic slowed to a crawl in and around the I-55 bridge in the weeks after the I-40 bridge closed. But traffic pattern changes and on- and off-ramp closures implemented on both sides of the river in early June have significantly decreased travel times in both directions.