A field inspection of the Interstate 55 bridge between Memphis and West Memphis has been completed, and "so far, there is nothing of concern," according to the Tennessee Department of Transportation.
"Inspectors continue to review the drone footage," according to the department. "A final report could tentatively be available by the end of the week."
For the past two weeks, the I-55 bridge has been the only way to cross the Mississippi River in a motor vehicle at Memphis, the largest city situated on the 2,320-mile river that divides the United States.
The 71-year-old, four-lane bridge on I-55 is also known as the Memphis and Arkansas Bridge, or to Memphians as just "the old bridge."
Three miles to the north, at least from the Tennessee side of the river, the Interstate 40 bridge has been closed since May 11, when a crack was found in a steel-box beam during a routine inspection. The 48-year-old structure is officially known as the Hernando de Soto Bridge, or "the new bridge."
The I-55 bridge is a mile long.
The I-40 bridge is 3.3 miles long.
It was built to span the entire 3-mile floodway, said Rob Rash, CEO and chief engineer for the St. Francis Levee District of Arkansas.
Traffic between Arkansas and Tennessee has been routed over the I-55 bridge while inspection and repair efforts are underway on the I-40 bridge.
Dave Parker, a spokesman for the Arkansas Department of Transportation, said each bridge normally would carry about 45,000 vehicles per day.
Nichole Lawrence, a spokeswoman for the Tennessee Department of Transportation, said a traffic sensor counted 66,238 vehicles traveling across the I-55 bridge on May 18.
"The additional traffic from the I-40 bridge does not overload the I-55 bridge," the Tennessee department said on its website, tn.gov/tdot. "The bridge will see the same traffic loads, but for a longer duration during peak hours."
This appears to be the first time since 1973 that only one bridge has been open to vehicular traffic across the Mississippi River at Memphis.
"I have no records showing the bridge has been closed like this before," said Lawrence. "Any construction work on the bridge in the past has taken place under traffic."
In its daily update Sunday, the Tennessee department said that "work on the bridge is progressing nicely."
Kiewit Infrastructure Group, the contractor hired for the repair, has been working 24 hours a day, according to the update.
The company has been installing fabricated steel plates on each side of the fractured section to secure the bridge for permanent repairs. The next phase is to remove and replace the damaged piece.
"The drilling and bolting of 315 holes for the outside steel plate were completed last night," the Tennessee Department said in Monday's update. "Now the brackets can be installed, and the drilling can begin on the 72 holes in the back plate."
A restriping project was completed Sunday to improve the traffic flow at I-55 and Crump Boulevard in Memphis, according to the Tennessee department.
"Ramps around the Crump interchange will remain closed during bridge repairs to help traffic flow on I-55 by not competing with merging ramp traffic," according to the Sunday update.
The fracture in the I-40 bridge has been traced by the Arkansas Department of Transportation back to at least 2019, when it was missed by inspectors during an annual review, but photos from a canoeist show the crack as far back as 2016.
"The fracture, or crack, is in a steel support beam that is critical to the structure of the bridge," the Tennessee department said on its website. "For that reason, the bridge is closed to all interstate traffic until repairs can be made."
"It is not clear what caused the fracture. Generally, the root cause of mechanical fracture can be overload, shock, fatigue or stress; but the exact cause can be difficult, if not impossible, to determine. Following the completion of repairs on the bridge, the damaged steel will be preserved for detailed forensic investigation."
A week after the crack was discovered, the Arkansas department fired the leader of the inspection team that missed it in 2019 and 2020.
Officials from Arkansas and Tennessee -- which share responsibility for maintenance of the bridge -- have been unable to provide a concrete timeline for the bridge's reopening, saying only that it could take several months.
The most significant work done in recent years on the I-40 bridge involved a "seismic retrofit" from 2000 to 2015, according to the Tennessee department's website.
Seismic retrofitting is the modification and reinforcement of existing bridges to make them more resistant to earthquakes. Memphis is in the New Madrid seismic zone. The seismic retrofit will allow the bridge to be able to withstand a 7.7 magnitude earthquake, according to the Tennessee department.
The next-closest bridge over the Mississippi River is on U.S. 49 near Helena-West Helena, about 70 miles south of Memphis.