On Tuesday night, the world’s largest steam locomotive, Union Pacific’s Big Boy No. X4014, returned to life¹, and yesterday it made its first test run in preparation for a steam locomotive “race” starting tomorrow.

Both of Union Pacific’s historic steam locomotives – Big Boy No. 4014 and the Living Legend No. 844 – will be touring the Union Pacific system throughout 2019 to commemorate the transcontinental railroad’s 150th anniversary. Tomorrow they’ll be kicking off those celebrations with a “race” from Cheyenne WY to Ogden UT, where they will mark the 150th with a celebration day on 9th May.

The main 150th celebrations are being held at at Promontory Summit Historic Park UT, where the Golden Spike was originally tapped into place on 10 May 1869, joining the Central Pacific and Union Pacific railroads. Sadly Union Pacific no longer has tracks near Promontory Summit. They were removed to support the scrap metal projects during World War II. Hence the celebration at Ogden Union Station the day before.

The huge 600-ton 4000-class 4-8-8-4 locomotives were designed to haul long trains of heavy freight over the mountains of Utah & Wyoming. They were so big, they were articulated to get round the tight mountain curves.

Twenty-five of them were built between 1941 and 1944 and were in service till 1959. Eight were preserved in museums, until 2013 when one of them, #4014, was sold by the Rail Giants Museum, Pomona, California, back to Union Pacific who had grand plans for its restoration and use.

This video shot in 2015 gives an idea of the scale of that restoration.

Union Pacific have also produced an interactive history map explaining how the Intercontinental Railway was created.

¹ X4014 was spotted moving for the first time under her own power late on Tuesday night. She is now the world’s only operating Class 4000 Big Boy locomotive.