Up Big Boy 2025 2025 Schedule. Union pacific's famed big boy no. 4014, the world's largest steam locomotive, will return to the rails in 2025 for a tour celebrating the railroad's deep history.
Union pacific has released a detailed schedule for “big boy” 4014’s upcoming tour across wyoming, utah, nevada, california and idaho in july, including a public excursion over the legendary donner pass. 4014’s “westward bound tour” to roseville, california, and back, which runs june 30 through july 26, and will include one excursion — july 14.