In its prime, a massive steam locomotive known as Big Boy No. 4014 was a moving eruption of smoke and vapor, a 6,300-horsepower brute dragging heavy freight trains over the mountains of Wyoming and Utah.
It's been silent for half a century, pushed aside by more efficient diesels, but now it's coming back to life. The Union Pacific Railroad is embarking on a yearslong restoration project that will put No. 4014 back to work pulling special excursion trains. (AP)