LITTLE ROCK Ark.—A crack in a steel beam that forced the closure of the Interstate 40 bridge connecting Arkansas and Tennessee for three months likely began when the span was fabricated in the 1970s and went undetected for years, a report by Arkansas’ Transportation Department released Thursday said.
A forensic investigation by an outside firm hired by the department said the crack occurred in a weld between two plates during the bridge’s fabrication. Those welds were more susceptible to cracking because of the type of steel and welding method used then, the department said.
