

Union Pacific
4-8-8-4 locomotives were owned exclusively by the Union Pacific. Rumored to be named the “Wasatch” class, they acquired the name “Big Boy” after an ALCO factory worked scrawled the text on the first unit’s smokebox during construction. They ran from 1941 to 1959.
ROAD NUMBER SPECIFIC FEATURES:
Santa Fe
With their stable performance at speed and ability to handle large trains, Santa Fe found the 4-8-8-4 concept to be appealing. They took delivery of their 6000 class in 1944 to help handle wartime traffic. ATSF had experimented with compound articulated locomotives in the 1910s, but they were never entirely successful. Buying UP’s design “off-the-shelf” from ALCO was the logical choice, then.*
*Alternate history- some facets have been massaged
ATSF FEATURES:
Southern
Southern was also hoping to alleviate wartime traffic constraints when they went to ACLO for 4-8-8-4 locos in 1944. Pleased with their 2-8-8-2 “Chesapeake” class, the Big Boy wheel arrangement was a natural progression and would prove itself on the steep grades throughout the southeast.*
*Alternate history- some facets have been massaged
SOU FEATURES:
PROTOTYPE SPECIFIC INFORMATION
The Union Pacific’s Overland Route, the eastern portion of the Transcontinental Railroad, was built west of Omaha, across Nebraska and Wyoming, and on into Utah. The steepest grade was the eastbound climb on the Echo Canyon line through the Wasatch Mountains just east of Ogden, Utah. Forty 4-6-6-4 Challenger locomotives were acquired in 1936 and 1937 to move fast freight over the grades in Utah and Wyoming. They were rated at 4,290 tons across Wyoming, but were limited to 3,100 tons eastbound through Echo Canyon.
Union Pacific wanted something that could make the same speeds as the Challengers but could carry the entire 4,290-ton train over the Wasatch Mountains without a helper. The easiest solution was to scale up the successful Challenger design by adding another pair of drivers to each half of the locomotive, thus making a 4-8-8-4.
In 1941, UP placed an order for 20 4-8-8-4’s, numbered 4000 through 4019, with the American Locomotive Works. Each engine cost $265,174. According to legend, an unidentified machinist at the ALCO plant is responsible for the name “Big Boy”, having scrawled the name in chalk on a partially completed locomotive.
The Big Boys were exactly what the railroad wanted. They were coal burners with 68-inch drivers, 135,375 pounds of tractive effort and 6,000 horsepower. They started service on the line from Ogden to Green River, Wyoming and their operating range soon increased to cover the line all the way to Cheyenne.
4-8-8-4 LOCOMOTIVE FEATURES:
SOUND-EQUIPPED MODELS ALSO FEATURE
PRIMED FOR GRIME MODELS FEATURE
LEGENDARY LIVERIES
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