Once one of the heaviest steam locomotives in the world, the Big Boy 4014 recently stumbled into a mission. The famous Union Pacific Big Boy was the heaviest steam locomotive ever built when it became operational in the 1940s. An icon of the American railroads, it was retired from service in 1959 as the diesel age took hold. Recently, however, the last running Big Boy was tasked with the important mission of rescuing a freight train stalled in Nebraska. The video shows the 4014 gently pulling up and coupling with the freight train ahead. After a spell, it roars into...