#176 Union Pacific Big Boy 4023 & Centennial 6900


Two heavy-tonnage locomotives incorporating the best features of the day


This Mechanical Engineering Heritage Collection To pull heavy freight trains on fast schedules over long distances and mountain grades, the Union Pacific railroad purchased some of the largest steam and diesel-electric locomotives ever built. No. 4023 is one of twenty five "Big Boy" articulated steam engines operated between 1941 and 1959. It was specifically designed to haul fast, heavy eastbound freight trains between Utah and Wyoming, over a 1.14 percent grade. All of the Big Boys were coal-burning, stoker-fired, designed to run 7,000 horsepower at 70 miles per hour. They have been lauded in the industry as the highest horsepower, heaviest, and longest steam locomotives ever built. No. 6900 was the first of forty-seven 6600-hp "Centennial" diesel-electrics that saw service from 1969 to 1984. Like the Big Boys, 70 mph was attainable with heavy tonnage trains on level track. These locomotives were equipped with speed recorders, dynamic braking, cab signals, and turbochargers. Unlike the Big Boys, the Centennials were designed to operate over all the UP main lines. While both designs were unique to the Union Pacific, they incorporated many of the best features of other contemporary American locomotives.

Union Pacific Big Boy 4023 & Centennial 6900

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Landmark Location

Kenefick Park Abbott Drive & 6th Street
Omaha, Nebraska 68110


Union Pacific Railroad Company
1416 Dodge Street
Omaha, NE 68179

Visiting Info

Free. Phone (402) 444-5900 Hours: 10:00am - 7:00pm; Closed during the Winter.

Ceremony Notes

June 1994

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