Big Boy & The Mother Road. UP 4014, the largest operating steam locomotive in the world, is close to completing it's first excursion day for the RailGiants Train Museum as the massive 4-8-8-4 and it's 23-car train approach Daggett as it heads for Yermo to layover for the night. This location on the railroad is one of the many where the original Route 66 parallels the tracks, once owned and operated by the Atchison, Topeka and Santa Fe Railway, making for an interesting composition as the 1941 product of the American Locomotive Company heads east.