PRE-ORDER: Rapido 1111025 - EMD SD70AC w/ Flared Rad (DC Silent) CSX (CSXT) 4725 YN3c - N Scale

Photo Courtesy: Jeff Lassahn

Introducing the all-new Rapido EMD SD70MAC in HO and N scale!

Rapido’s model has been designed from the ground up to create a wide array of phase variations on the SD70MAC, including late production units for CSX and Alaska Railroad, Metra’s unique SD70MACH, and a variety of rebuilds.

The SD70MAC was a groundbreaking locomotive, as it truly ushered in a new era of power policies and orders. It was the first production AC traction freight locomotive in North America, with Burlington Northern receiving its first 9400 series units in late 1993. The key difference with AC traction motors is their higher durability compared to DC traction motors. AC motors do not burn out at low speeds from overheating, though they cost more than DC motors.

For some railroads in the 1990s, this was a clear advantage. BN had a booming volume of Powder River unit coal trains moving to powerplants, facing long, tough grades along the way. Colorado’s Joint Line is one, with a 40+ mile 1-1.5% continuous grade. BN was using sets of 5 DC SD40-2s and C30-7s as head end power to get up that grade, and the train had to stay above 10mph or more to prevent burnout on the DC traction motors. 

With AC traction motors on SD70MACs, BN only needed three units on the head end, and they could grind away at any speed to conquer the grade. For BN, the cost advantage on this heavy haul traffic was huge, so the SD70MAC orders continued into the BNSF era. Ultimately, BNSF rostered 795 SD70MACs, far more than any other railroad. At present, much of the fleet is in storage, but the remaining active units are an interesting mixture of patched executive schemes and rebuilt SD70MACs.

CSX was the next largest buyer of SD70MACs, as it was also the other primary railroad to adopt AC power in the 1990s. Several modest batches of middle-production units were ordered in the late 90s. After a pause of a few years, CSX then came back for another 75 units in 2003 and 55 more units in 2004. Both orders combined were numbered 4700-4830. All CSX units have always been stencilled as “SD70AC” on CSX, regardless of order group or rebuild status.

These later CSX orders were unlike any SD70MACs that came before, as EMD was now manufacturing to Tier-1 emission standards for the engine and cooling system. That in turn had changed their styling and design on SD70Ms and SD70MACs. All of CSX’s later SD70MACs came with flared rear radiators and a hood that replaced round corners with angled bevels on all edges. Additionally, CSX requested the Eco-Trans Auxiliary Power Unit (APU) to be included, which rearranged the equipment doors and vents in the long hood under the radiators.

While BNSF has many units in storage, CSX has taken a much different approach: a majority of its SD70MAC fleet has been rebuilt, which CSX still calls SD70ACs. These rebuilt units can be found system wide leading all types of trains, including high-priority intermodal trains, defying the perception that SD70MACs are just for hauling coal.

Several other railroads have also rebuilt SD70MACs, all in a similar manner. The original Siemens electrical gear is replaced by newer Mitsubishi equipment similar to that found in the SD70ACe line. For some rebuilds, like CSX and KCS, the new equipment requires more height under the dynamic brake grid, so that in turn is raised up and no longer flush with the roof. KCS rebuilds have a complicated history, but several still are in CPKC mainline service in attractive Belle paint. 

Photo Courtesy: Jeff Lassahn

Photo Courtesy: Craig Walker 

Far more KCS units have been much stranger: the Metra SD70MACH. The units are no longer C-C, but B1-1B, as the inward axle facing the fuel tank on each truck no longer has a traction motor. The hood retains the original rounded corners of the KCS cores, but the rear section is Tier-1 style, with flared radiators and squared corners. The walkways have extra protection, and at the front and rear there are stainless steel buffer plates for coupling to passenger car diaphragms. Finally, there is the Metra lighting package: a nose headlight, nose marker lights for pushing, a high LED gyralight, and an emergency beacon on the cab. Metra ordered 15 units from Progress Rail that first arrived in 2022, and has since exercised the options for 42 total units (24 are on the property and in service.)

Metra’s SD70MACHs are not the first passenger-capable SD70MACs, though; that title belongs to the Alaska Railroad’s late-model SD70MACs. Alaska Railroad had a fleet of sixteen typical mid-production SD70MACs for freight service, but did not have a good solution for powering its bustling seasonal passenger service. The solution was to take the CSX’s Tier 1 SD70MAC design, which had rearranged the rear of the hood to add an auxiliary power unit, and use that space to add HEP for the first time. The first 8 units arrived in 2004, and an additional 4 arrived in 2007 as the last SD70MACs manufactured. The twelve unit fleet is essential to Alaska Railroad’s operations, because the passenger schedule is dramatically higher than freight in summer, but very low in winter. Every major passenger train features the SD70MACs as power, but they also freely mix into freight service as needed. This makes them the only true mainline freight and passenger locomotives in North America. 

The N Scale SD70MAC Locomotives Features:

• Late-production Tier 1 units for the first time in plastic!
• Metra rebuilds, also a first in N scale!
• Multiple nose and cab variations (Nose light, high headlight, gyralight)
• Railroad and era appropriate PTC antennas, where applicable
• Working headlights, ditchlights, and extra lights.
• Metra: features a gyralight, marker light, and emergency light on the nose and cab.
• Metra: tons unique rebuild details, including HEP, end buffers, and more
• CSX: Unique rear of hood housing Eco-Trans Auxiliary Power Unit
• Road specific horns and roof detail
• Separate grab irons and handrails installed at the factory
• Heavy, die-cast chassis with a powerful motor and dual flywheels
• MoPower capacitor system for uninterrupted DCC running
• DC/DCC ready or Dual-Mode DC/DCC/Sound
• Suggested minimum radius: 11”