Why the Big Boy No Longer Runs on Coal

The original Union Pacific Big Boys burned coal — and Big Boy No. 4014, restored to operational steam in 2019, burns waste petroleum coke instead. The conversion wasn't a preservation aesthetic choice. It was a practical engineering decision driven by the collapse of the coal supply and handling infrastructure that once supported steam operations across the Union Pacific system. Coal towers, ash pits, and water treatment facilities that served the steam fleet were demolished decades ago and won't be rebuilt for a single locomotive. Petroleum coke — a refinery byproduct with high carbon content and sufficient BTU output to fire a 4-8-8-4 boiler — became the operationally viable substitute that let the railroad run its most famous locomotive without rebuilding the infrastructure that originally fed it.