Union Pacific “Big Boy” No. 4014

Design and Construction

No. 4014 was one of twenty five “Big Boy” class locomotives built by the American Locomotive Company (ALCO) in Schenectady, New York, for Union Pacific Railroad, with this particular engine turned out in November 1941. Union Pacific commissioned the class to solve a specific operating problem: freight trains climbing the 1.14 percent ruling grade over Sherman Hill and through the Wasatch Range in Utah needed far more sustained pulling power than any existing design could deliver without doubling locomotives on every train. ALCO’s engineers answered with a simple articulated locomotive of 4-8-8-4 wheel arrangement, a design that split the enormous boiler’s power between two sets of eight driving wheels on a hinged frame so the machine could still track through mountain curves. At roughly 132 feet long and weighing well over a million pounds with its tender loaded, the Big Boy became, and remains, the longest and among the heaviest steam locomotives ever built for a common carrier railroad. The class was intended purely as a freight hauler, not a passenger flagship, and its rugged, unglamorous silhouette reflects that purpose.

Revenue Service, 1941 to 1961

No. 4014 spent its working life almost entirely on Union Pacific’s Sherman Hill route between Cheyenne, Wyoming, and Ogden, Utah, hauling heavy tonnage freight that would otherwise have required multiple smaller locomotives. Wartime traffic during the final years of World War II put the Big Boy fleet to particularly hard use, and 4014 continued in mainline freight service through the 1950s as diesel locomotives were gradually phased in across the rest of Union Pacific’s roster. Steam’s decline was already well underway elsewhere on the railroad by the time 4014 was set aside from active duty; it was formally retired on December 7, 1961, one of the last Big Boys still turning a wheel in everyday freight work.

First Retirement and Museum Years

Rather than being scrapped, No. 4014 was donated by Union Pacific to the Railway and Locomotive Historical Society, arriving on January 8, 1962, at what is now the RailGiants Train Museum on the Los Angeles County Fairgrounds in Pomona, California. There it sat as a static display for more than fifty years, one of eight surviving Big Boys scattered across museums and parks in the years after steam’s retirement, admired by generations of visitors but never expected to move under its own power again.

Return to Union Pacific and Restoration

That changed in 2013, when Union Pacific reacquired No. 4014 from the museum as part of the planning for the 150th anniversary of the transcontinental railroad’s completion in 2019. The locomotive left Pomona in January 2014 and arrived at Union Pacific’s steam shop in Cheyenne, Wyoming, that May, where it sat undergoing evaluation and disassembly before full restoration work formally began in August 2016. The Cheyenne crew, the same shop responsible for maintaining sister engine No. 844, rebuilt bearings, flues, valves, and the air brake system and re-turned the wheel sets. The most consequential change was a conversion from coal to oil firing, which required modifying the cab and tender fuel system; the swap dramatically simplified servicing on the road and reduced the smoke and cinder output that had made coal firing increasingly impractical for excursion use. The restoration, spanning roughly five years from reacquisition to completion, was covered closely by railfan and mainstream press alike given the sheer scale and rarity of returning a machine this size to operating condition.

Return to Steam and Excursion Era

No. 4014 moved under its own power for the first time in nearly six decades in May 2019, and Union Pacific timed its public debut to the Golden Spike sesquicentennial commemorations at Ogden and Promontory Summit, Utah, retracing portions of the original transcontinental route it had once served in freight harness. Since then it has made periodic multi-state tours rather than running on a fixed annual schedule; in August 2021 it toured ten states across the central and southern United States, from Wyoming down through Colorado, Kansas, Oklahoma, Texas, Louisiana, Arkansas, Missouri, Illinois, and Nebraska, drawing large crowds at every stop. A planned 2022 tour that would have taken the locomotive into the Pacific Northwest for the first time since restoration was postponed by Union Pacific, which cited ongoing supply chain congestion across its freight network rather than any mechanical fault with the locomotive itself. In place of that trip, 4014 traveled to Denver in July 2023 for a public steaming display and a short excursion hosted by the Union Pacific Museum before returning to Cheyenne.

Current Status

No. 4014 is based at Union Pacific’s Cheyenne steam shop and remains the only currently operational Big Boy among the eight examples preserved in North America, the rest being static museum or park displays. It continues to make public appearances tied to Union Pacific’s heritage program, alternating between multi-state tours and shorter regional outings depending on shop schedules and network conditions, and is maintained by the same crew that keeps No. 844 in excursion-ready condition.

Recognition

As the sole operating example of the largest class of steam locomotive ever built, No. 4014 is widely regarded within the railroad preservation community as one of the most significant steam locomotives in existence, and its public appearances routinely draw the largest crowds of any operating steam excursion in the United States.