FILE - In this Dec. 20, 2019, file photo, shipping containers are offloaded at a BNSF Railway intermodal facility as the sun sets in Edgerton, Kan. The heads of the nation's two largest rail unions said Sunday, Sept. 11, 2022 that the freight railroads' move to begin delaying some shipments ahead of this week's looming strike deadline is only an attempt to get shippers to increase the pressure on Congress to intervene and block a work stoppage by imposing a contract on workers. (AP Photo/Charlie Riedel, File)