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| SD70ACe | |
|---|---|
| Name | SD70ACe |
| Powertype | Diesel-electric |
| Builder | Electro-Motive Diesel |
| Builddate | 2004–2015 |
| Totalproduction | 580+ |
| Aarwheels | C-C |
| Primemover | EMD 16-710G3C-ES |
| Enginetype | V16 two-stroke diesel |
| Aspiration | Turbocharged |
| Displacement | 11,360 cu in |
| Tractionmotors | AC traction motors |
| Maxspeed | 75–80 mph |
| Locale | North America, Australia |
SD70ACe. The SD70ACe is a high-horsepower diesel-electric freight locomotive built by Electro-Motive Diesel for major North American railroads and export customers. Designed to meet Environmental Protection Agency emissions regulations while providing increased tractive effort and reliability, the model became a successor to earlier SD60 and SD70 family designs. It has been acquired by operators including Union Pacific Railroad, CSX Transportation, BNSF Railway, Canadian National Railway, and international buyers such as Freightliner subsidiaries.
EMD developed the SD70ACe in response to tighter Environmental Protection Agency Tier 2 emission standards and competition from GE Transportation offerings. The program drew on experience from the SD90MAC and SD70M projects and incorporated the 16-cylinder EMD 710 series prime mover, electronic engine control systems, and insulated-gate bipolar transistor (IGBT) inverter technology licensed within EMD. Design priorities included compatibility with existing North American freight operating practices, improved adhesion control for heavy haul operations on lines such as those of Union Pacific Railroad and Canadian National Railway, and modular maintenance features used by fleets like BNSF Railway and CSX Transportation.
The locomotive is powered by the 16-cylinder, two-stroke EMD 710G3C-ES prime mover producing 4,300–4,500 hp depending on software and gearing, driving AC traction motors via IGBT inverters. The truck arrangement is AAR C-C with high-adhesion trucks similar to those used under SD70MAC and later SD9043MAC designs. Braking systems include dynamic and blended pneumatic systems compatible with Federal Railroad Administration standards. Onboard electronics implement EMD's microprocessor control packages and wheel-slip control routines common to fleets operated by Union Pacific Railroad, CSX Transportation, and BNSF Railway. Fuel capacity, cooling system sizing, and gearing were adjusted per customer: heavy-haul outfits like Canadian National Railway prioritized tractive effort while intermodal operators such as Norfolk Southern emphasized sustained high-speed performance.
Manufacturers and owners produced multiple variants and retrofits: cabs modified to crashworthiness standards influenced by Federal Railroad Administration regulations; emission calibration changes for Environmental Protection Agency tiers; and communications packages integrating Positive Train Control components for U.S. Department of Transportation mandates. Export versions were adapted for gauge and climate differences for customers linked to Aurizon, Pacific National, and other Australasian operators. Locomotives received modifications such as distributed power systems for BNSF Railway long trains, wheel-slip software updates used by Union Pacific Railroad, and auxiliary power unit retrofits for fuel economy initiatives championed by CSX Transportation.
Since introduction in the mid-2000s, classes were deployed across heavy-haul coal routes, intermodal corridors, and general merchandise service on networks including Union Pacific Railroad transcontinental lines, Canadian National Railway mainlines, and BNSF Railway corridors. Notable roster assignments involved unit groups operated in Powder River Basin coal trains, intermodal service linking Los Angeles and Chicago, and export leasers assigned to Australian grain and mineral routes associated with Australian Rail Track Corporation corridors. Fleet management programs at operators such as Norfolk Southern and CSX Transportation tracked mean distance between failures and overhaul intervals under regional maintenance regimes.
Operationally, the design delivered improved adhesion and reduced wheel slip compared with earlier DC-traction designs, translating to higher tonnage per crew and lower cycle times on grades like those on Loram-maintained lines and mountain divisions controlled by Union Pacific Railroad. Reliability metrics varied by operator and maintenance practice: fleets with proactive predictive maintenance, exemplified by programs at Canadian National Railway and BNSF Railway, showed longer service intervals, while earlier fleets required software and cooling upgrades to address turbocharger and electronics heat stress under heavy duty cycles. The model's AC traction system and microprocessor controls influenced subsequent EMD families and competitive offerings from GE Transportation and later manufacturers.
Several units have entered preservation or display with museums and heritage organizations such as the Illinois Railway Museum and regional railroad historical societies tied to Union Pacific Railroad heritage. The locomotive has been represented in various model railway scales produced by companies like Athearn, Kato USA, Bachmann Industries, and Walthers for HO and N scale collectors. Special-edition models commemorate road numbers from BNSF Railway, CSX Transportation, and Union Pacific Railroad paint schemes for enthusiasts and museum donors.