Authorities were forced to close a bridge spanning the Mississippi River between Arkansas and Tennessee after a crack was discovered on the bottom of the bridge truss, prompting the U.S. Coast Guard to halt boat traffic in the area. The Hernando de Soto Bridge, which includes Interstate 40, connecting West Memphis, Arkansas, and Memphis, Tennessee, was shut down after the Tennessee Department of Transportation said in a news conference on Wednesday. Emergency repairs started on the bridge on Tuesday, officials told local media. “A routine inspection of I-40 MS River Bridge revealed a crack that requires further investigation … we’re working with [Tennessee officials] to make sure the bridge is safe for motorists before we reopen it,” the Arkansas Department of Transportation also wrote. The crack, authorities said, is critical to the bridge’s structural integrity. “This fracture had the potential of becoming a catastrophic event,” Lorie Tudor, director of the Arkansas …