A 5000 hp EMD DD35A leads a Union Pacific freight train across the Columbia River on the John Day Bridge.

Union Pacific Railroad Colorphoto.

(Audio-Visual Designs, Earlton, NY, Public domain, W. Lenheim Collection)



The EMD DD35A, also known as the EMD DDA35, was a 5,000 hp (3,730 kW) diesel-electric locomotive of D-D wheel arrangement built by General Motors Electro-Motive Division exclusively for the Union Pacific Railroad. They were a cab-equipped variant of the previous, cabless booster (B unit) EMD DD35 (sometimes erroneously called the 'DD35B'). Fifteen DD35A locomotives were built between May and July 1965; they were assigned road numbers 70 through 84. This request also led to the introduction of the ALCO Century 855 and GE U50. A further development of the 8 axle, twin-engine locomotive produced the final, best known type, the DDA40X "Centennial".


Union Pacific EMD DDA35 74 at North Platte, Nebraska, October 19, 1969. Photographer unknown.

(Craig Garver, Public domain, https://www.flickr.com/photos/digitalrailartist/50308721563/)



Like its cabless predecessor, the DD35A was essentially two EMD GP35 locomotives on a common frame, riding on a pair of 4-axle Flexicoil trucks. The cab of a GP35 was fitted to the front end, requiring a longer frame than the DD35; the fuel tank beneath was lengthened, and the center pass-through walkway was offset a little to the rear because of the single cab. Another difference was that the DD35A was fitted with the new flared radiator section EMD was testing on its EMD 645-engined demonstrators (the prototype SD40 demonstrators).

The DD35s were initially quite unreliable; some of this was blamed on sand from the internal sandboxes getting in electrical gear, so new sandboxes were fitted on the walkways in 1969. The DD35s were among the last EMD road units to be built with DC generators and old-fashioned switchgear, which were more maintenance intensive than the later AC/DC equipment.

Once teething troubles had been overcome, the DD35s were reasonably successful, but they were less flexible than smaller units and thus with the economic downturn of the early 1980s they were withdrawn from service. They spent their final months of service operating around Salt Lake City, Utah before their retirement by 1981. No examples of the DD35 type were preserved.


A pair of 5,000 hp locomotives at the UP facilities at North Platte, Nebraska. On the left, GE U50D No. 53, on the right EMD DDA35 No. 82.

Union Pacific Railroad Colorphoto.

(Audio-Visual Designs, Earlton, NY, Public domain, W. Lenheim Collection)


Original buyers

Owner Quantity Numbers
Union Pacific Railroad 15 70-84

Union Pacific EMD DD35A 82 at Cheyenne, Wyoming, June 4, 1969. Photographer unknown.

(Craig Garver, Public domain, https://www.flickr.com/photos/digitalrailartist/50358030466/)



Type and origin
Power type: Diesel-electric
Builder: General Motors Electro-Motive Division (EMD)
Build date: 1965
​• AAR D-D
Gauge: 4 ft 8+1⁄2 in (1,435 mm)
Wheelbase Between truck centers: 65 ft 0 in (19.81 m)
Truck wheelbase: 17 ft 1+1⁄2 in (5.22 m)
Length: 88 ft 2 in (26.87 m)
Width: 10 ft 4 in (3.15 m)
Height cab roof: 14 ft 11+3⁄8 in (4.56 m)
Height overall: 16 ft 4 in (4.98 m)
Locomotive weight: 519,353 lb (235,575 kg)
Fuel capacity: 8,230 US gal (31,200 L; 6,850 imp gal)
Prime mover: Dual EMD 16-567D3A
Engine type: V16 diesel
Aspiration: turbocharged
Cylinders: 16
Safety systems: Leslie Supertyfon model S5TRRO or S3LR horns
Performance figures
Power output: 5,000 hp (3,730 kW)
Operators: Union Pacific
Numbers: 70 – 84
Disposition: All scrapped