LITTLE ROCK, Ark. — An inspector who failed to discover a crack in the Interstate 40 bridge linking Arkansas and Tennessee that prompted the span’s closure has been fired, Arkansas transportation officials said Monday.

Arkansas Department of Transportation Director Lorie Tudor said the inspector was fired after drone video showed the crackon the bridge spanning the Mississippi River in May 2019. Tudor said the crack was not noted by the inspector in his reports that fall or the following year.

“This is unacceptable,” Tudor said at a news conference. The department did not immediately name the employee and said the incident is also being referred to federal investigators.

Arkansas’ DOT on Monday released an image and video from the drone, which showed the crack. The drone footage was taken by a consultant inspecting the bridge’s cables.

Traffic on the six-lane bridge was shut down last Tuesday after inspectors found a “significant fracture” in one of two 900-foot horizontal steel beams that are critical for the bridge’s integrity. River traffic under the span was closed Tuesday but reopened on Friday.

The closure has impacted a heavily used corridor and raised concerns about shipping and delivery costs. The Arkansas Trucking Association on Friday estimated the closure would cost the trucking industry at least $2.4 million a day.

Traffic was being rerouted to Interstate 55 and the 71-year-old Memphis & Arkansas Bridge, about 3 miles south.

Arkansas and Tennessee authorities have not given a timeline for when the bridge will reopen. The Tennessee Department of Transportation said Monday that the I-40 bridge repair will be conducted in two phases, and both steps must be completed before the bridge can be reopened for road traffic.

The first step is installing steel plates on each side of the fractured beam to provide stability for crews to permanently replace the damaged parts, TDOT said in a statement. The plates are being made and fabrication should be completed by Wednesday, TDOT said. The second phase involves removal and replacement of the damaged piece of the bridge.

Nebraska-based Kiewit Corporation was selected Monday afternoon for the bridge repair work, Arkansas DOT spokesman Dave Parker said. Tennessee transportation officials said Kiewit could start work as early as Wednesday.

Tennessee’s DOT also said it will review the condition of the I-55 bridge “out of an abundance of caution.” The drone review is expected to occur Tuesday or Wednesday.

Tudor said all “fracture critical” bridges that had been inspected by the fired employee will be re-inspected. She said the fired employee, who had worked for the department for about 15 years, did not follow proper protocol in the bridge’s inspection.

“The way we’re supposed to inspect the bridge is you literally go inch by inch along that beam and physically inspect every inch of the beam,” she said. “That did not happen.”

Tudor said the department is making changes to its inspection program to add additional checks, including the use of a new drone to aid in inspecting bridges. Tudor said last week that the bridge’s damage could have led to a “catastrophic” event had it not been discovered.

The bridge’s closure comes as the White House is negotiating with a group of Senate Republicans on an infrastructure package. Democrats have called the I-40 bridge damage an example of the urgent need for additional funding to fix the nation’s bridges and roads.

Republicans have called for a infrastructure plan with a smaller price tag than President Joe Biden’s and with a narrower definition of public works.