Electro-Motive Division’s GP20 was the company’s first four-axle model to be fitted with a turbocharger, but its roots trace back to one of EMD’s customers, Union Pacific.
Union Pacific began experimenting with several turbocharger models in the mid-1950s on a number of its GP9 and GP9Bs, creating the first GP20s in-house. As UP’s program continued, it asked EMD to turbocharge a handful of its GP9 and GP9Bs with EMD’s turbocharger which was in development at the time, thus providing another option for Union Pacific to evaluate. Ultimately, EMD’s turbo would become the superior design, with UP changing a number of its test units to EMD turbochargers or converting the units back to GP9/GP9Bs.
With EMD’s GP20 ready to hit the road in the late 1950s, the company built a four-unit set of GP20s decked out in a silver and blue demonstrator scheme to test on various railroads. The results garnered interest by only eight railroads for 260 units, with over half the GP20s ordered by three railroads: Santa Fe; Chicago, Burlington & Quincy; and Great Northern. Ironically, EMD’s non-turbocharged version of the GP20, the GP18, would command more sales and a longer customer list during the same time frame. The 1,800-hp GP18 would sell 390 units domestically with Missouri Pacific the largest customer by far, ordering 146 copies.
Of the original customers, BNSF Railway, which inherited many Santa Fe and Burlington Northern (former CB&Q) GP20s, would become the final Class I to operate the model. The last of its units were parked for good in 1999. GP20s, while still in service on short lines and other properties, are becoming harder to find. Pioneer Lines, which operated a number of short line railroads across the United States, had a significant number of GP20s spread across its properties. The sale of the company last year to Patriot Rail has greatly reduced the number of active GP20s, with Patriot Rail actively upgrading power on many properties.