EMD SD70MAC Alaska Railroad #4006

Technical Specifics

The EMD SD70MAC entered production in 1993 as Electro-Motive Division's answer to the growing demand for high-horsepower AC traction locomotives in North American freight service. It represented EMD's direct competitive response to General Electric's AC4400CW, which had begun attracting orders from major railroads eager to exploit the superior pulling characteristics of alternating current traction technology, particularly on heavy-grade mountain operations. Burlington Northern was among the earliest and largest customers, acquiring substantial numbers of SD70MACs for service across its extensive western network, where the locomotives proved well suited to coal train operations in the Powder River Basin and demanding mountain territory. Conrail, CSX, and Transportación Ferroviaria Mexicana also placed orders for the SD70MAC, though Burlington Northern and its successor BNSF Railway accounted for the majority of units built. The Alaska Railroad ordered a distinctive variant equipped with head-end power capability, making those units suitable for combined freight and passenger service. So satisfied was the Alaska Railroad with the model's performance that it continued placing special orders even after EMD had transitioned its standard production to the successor SD70ACe in 2004. The final delivery of Alaska Railroad SD70MACs took place in late 2007, extending the model's production run well beyond its nominal end date. In total, approximately 1,109 SD70MACs were constructed across the model's production life, which formally spanned 1993 to 2007. The SD70MAC's legacy rests substantially on its role in demonstrating that EMD could compete effectively in the AC traction market, a segment that GE had moved into aggressively during the early 1990s. Although the SD70MAC was ultimately succeeded by the SD70ACe, which incorporated design revisions to meet tightening EPA emissions standards, the earlier model established AC technology firmly within EMD's product line and provided railroads with a capable and reliable heavy freight locomotive that many operators continued to run in revenue service decades after delivery.

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