EMD SD40T-2

An EMD SD40T-2 is a 6-axle diesel locomotive built by General Motors Electro-Motive Division. Power is provided by a 16-cylinder EMD 645E3 diesel engine capable of producing 3,000 horsepower (2,240 kW). The Southern Pacific's locomotive features a 4,400-US-gallon (16,700 l) fuel tank and is 70 feet 8 inches (21.54 m) long. The Rio Grande's locomotive features a smaller 4,000-US-gallon (15,100 l) fuel tank. A total of 312 examples of this locomotive were built for North American railroads between April 1974 and July 1980. This locomotive, along with the SD45T-2, are popularly called tunnel motors, but are officially referred to as SD40-2s with "cooling system modifications" (and the EMD manuals so state), because they were specifically designed to be more effective when operating in tunnels. The major differences between this locomotive and its non-tunnel motor cousin, the SD40-2, are the radiator intakes and radiator fan grills located at the rear of the locomotive. The radiator air intakes in this model were located along the deck to allow more fresh, cooler air to enter and less hot exhaust fumes lingering around the tunnel's ceiling.

This locomotive model was purchased by the Southern Pacific Railroad, its subsidiary Cotton Belt, and the Denver and Rio Grande Western Railroad. At one point Southern Pacific and then later the Union Pacific owned every SD40T-2.

In 2005 most of these units were in service on the Union Pacific or various leasing companies. By 2008 none were left in service on the Union Pacific with SP or DRGW reporting marks. DRGW 5371 was the last one retired from active service in March 2008, and now resides at the Utah State Railroad Museum in Ogden Utah. The Union Pacific still runs many of these units in its own livery.