Union Pacific DDA40X Centennial Loco Add-On
Union Pacific DDA40X Centennial Loco Add-On Steam header
Availability Currently available on Steam
Features EMD DDA40X at various stages of its career
Scenarios for the Sherman Hill route
Scenarios 4 Standard
Price £11.99
Link Steam logo Here!

The EMD DDA40X was an American diesel-electric locomotive built for the Union Pacific Railroad. At a length of over 98 feet and posessing two diesel engines (each 3,300 hp (2.46 MW)), it is both the most powerful single-unit diesel locomotive ever built and the longest.


In 1969 Union Pacific was retiring the later gas turbine-electric locomotives. Union Pacific had ordered EMD DD35s and DD35As to replace the turbines, and the DDA40X was a further development. Forty seven were built between June 1969 and September 1971, except the first one delivered in April in time to participate in the celebrations of the centennial anniversary of the completion of the Transcontinental Railroad driving the "Gold Spike Limited" and arriving in Salt Lake City, Utah, on the morning of May 10, 1969. The units were numbered from 6900 to 6946, with 6936 still in service.

By 1974, averaging 22,000 miles a month, most DDA40X units had run over 1,000,000 miles and needed more maintenance. Union Pacific began retiring its DD40Xs in 1984 due to rising maintenance costs, with all retired by the end of 1986. 13 have been preserved, with 6936 still in service with the Union Pacific Heritage Fleet, predominantly on excursion trains.

Train SimulatorEdit

For Train Simulator the EMD DDA40X was developed by DigitalTrainModel with assistance from Anthony Woods, Andreas Czudai, Rick Grout, Ricardo Rivera, Frank Stevens, and Martin Velozo. released the model through Steam on 8 January 2014.

The EMD DDA40X boasts in-cab lighting, step lights, a strobe light, number board lights, and interestingly for a locomotive, folding front and rear mirrors. Cab doors and windows are operable and noise changes whenever they are open.


  • Business tour - Today you have to do a special journey from Cheyenne to Laramie. You have the right of way. There are some delays on the departure time due to some problems with the preparation of the train, but they have faith in your ability to get to Laramie before 9:00 for a very important meeting with the UP managers! You can reach 70mph in some areas. Good luck!
  • Entering slowly to Cheyenne - You have been driving this train from Denver to Cheyenne. Now you must wait for the yard to be cleared for you. When this is done, the signals will allow you to continue.
  • Orders at Granite
  • Test by ELECTRO - MOTIVE - Your job today is to test the brand new DDA40X at high speeds and with loaded wagons. You have two SD40-2 at the end of the train just as a precaution. You must turn the locomotive around at the triangle, collect the wagons and then go to Buford.

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