The crack in a steel beam that forced an emergency three-month shutdown of the Interstate-40 Hernando De Soto Bridge across the Mississippi River earlier this year likely originated nearly 50 years ago during the component’s fabrication, according to a recently released forensic analysis commissioned by the Arkansas Dept. of Transportation.
Discovered during a routine above-deck inspection of the 3.3-mile-long structure in May, a ½-in thick top flange plate and 1-3/8-in thick vertical plate of the 900-ft-long, 32x26-in tie girder were found to be totally severed, with the fracture extending across nearly half of the bottom flange plate. Additionally, 9 ft of the weld connecting the inside web with the upper flange had separated as well.