NASHVILLE — It was meant to be a routine inspection. But when an engineer climbed out onto the Interstate 40 bridge over the Mississippi River this week, what he saw led to an urgent call to 911: “We need to get people off the bridge immediately!”
He had spotted a crack. He could not miss it, really. A critical beam was fractured to the point of being nearly severed.
The Hernando de Soto Bridge, which reaches from downtown Memphis into Arkansas, is inspected every two years, so the crack could have been there for weeks, months or well over a year. But in that moment, the inspector stressed to the 911 dispatcher on Tuesday, the bridge needed to be shut down right away to avert a disaster.
Since Tuesday, vehicles have been blocked from crossing over the bridge and vessels from passing beneath it. Officials are unsure just how long the shutdown will last, stirring fears of delays and disruption that could reach far beyond Memphis.
“Memphis is really a nerve center of this country from a supply chain perspective,” said William B. Dunavant III, the chief executive and president of Dunavant Enterprises, a global distribution and logistics company based in the city.
Hundreds of barges have been held up on the Mississippi River, according to Coast Guard officials. And the more than 35,000 vehicles that cross the bridge daily — about a third of them commercial traffic — have had to rely on the only other nearby bridge. Another alternative requires driving more than 100 miles north and crossing into Missouri.
“We absolutely want to get the bridge open as soon as possible, but we’re not going to shoot from the hip here,” Clay Bright, Tennessee’s transportation commissioner, told reporters. “We want to have the best fix, long term, to get this bridge back open.”
The shutdown has underscored the decay of the nation’s infrastructure and the dangers that it can pose. President Biden has focused on bridges as part of an ambitious and expensive proposal to fund a widespread overhaul and upgrade of roads, airports, public transportation, railways and ports across America.
The Interstate 40 bridge, which opened in 1973 and has two 900-foot spans, was last inspected in 2019. It is overseen by state transportation officials in both Tennessee and Arkansas; Arkansas is responsible for inspections, and Tennessee handles maintenance, officials said.
“It’s fortunate that routine inspection averted a potential disaster, but the state of our crumbling infrastructure is deeply troubling,” Representative Steve Cohen, a Democrat from Memphis, said in a statement, adding, “The closure of a major thruway will negatively affect us both here in Memphis and around the country, which depends on us as a national connection hub.”
Memphis, with its perch on the Mississippi River, has long leveraged its geography, establishing itself as nucleus for river, rail and road transportation. And as the headquarters for FedEx, Memphis has the busiest cargo airport in the world.
“We are the capital city, we’re the mecca of sorts, when it comes to transportation,” said Robert S. White II, the chief public policy officer for the Greater Memphis Chamber.
Combined with the other bridge on Interstate 55, on an older, four-lane structure south of downtown, more than 100,000 vehicles cross the river every day. And an average of 430,000 tons of commodities pass under the bridges daily, according to the Waterways Council — or 150 million tons each year.
Mr. Dunavant said companies had started to pay truck drivers a surcharge, as trips into Arkansas that had been roughly 90 minutes were taking at least twice as long to complete.
The bridges are part of one of the nation’s busiest trucking corridors, Mr. Dunavant said. “All of the sudden this happened,” he said. “That creates a real supply chain choke from a trucking standpoint.”
The longer the closures last, the more significant of an impact they will have on the region’s economy. “We’re listening every day just to see if we can get more insight and definite timelines for what this could be, and we’re hoping for the best,” Mr. White said.
Officials said that water traffic was expected to resume once inspectors had a better understanding of the bridge’s integrity and the threat of any collapse. Transportation industry officials familiar with the process said that the river could be reopened by late Friday at the earliest.
“We are hopeful that we can find a solution that would allow us to proceed with some opening of traffic,” Paul Degges, the chief engineer for the Tennessee Department of Transportation, said in a news conference on Wednesday. “But right now we just don’t know.”
The discovery of the crack has prompted what officials described as a meticulous examination of the bridge and its structural integrity, which could take weeks as engineers try to determine whether there is an imminent threat of collapse and if the structure is sound enough for crews to begin repair work.
“This fracture had the potential to become a catastrophic event,” Lorie Tudor, the director of the Arkansas Department of Transportation, told reporters.
It is unclear how long the fracture had been there. “In theory, the crack could have occurred five minutes after the last inspection,” Mr. Degges said.
Based on signs of corrosion and the appearance of the metal inside the crack, which darkens from exposure to air, engineers said it was quite likely that the fractures had been there for at least a week. “The whole bridge needs to be inspected to see if the cracking is widespread,” said Adel E. Abdelnaby, a civil engineering professor at the University of Memphis.
The damaged beam consists of four separate plates; three had been severed, and the fourth was 20 percent fractured, officials said. A full fracture of that final part of the beam, Professor Abdelnaby said, had the potential to cause “a catastrophic failure.”
“We were lucky the bottom plate didn’t give away completely,” he said.