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The Siemens Charger SC-42DM is a forthcoming dual-mode (diesel-electric and third-rail electric) locomotive being built by Siemens Mobility for the MTA's two commuter railroads: the Long Island Rail Road (LIRR) and the Metro-North Railroad. The locomotive is a specialized variant of the successful Siemens Charger platform and is being procured to replace the railroads' aging dual-mode fleets—the EMD DM30AC on the LIRR and the GE P32AC-DM on Metro-North.

The SC-42DM will be powered by a 16-cylinder Cummins QSK95 diesel prime mover, a modern engine compliant with the stringent EPA Tier 4 emissions standards. This engine will provide a nominal output of 4,200 horsepower (3,100 kW), offering a significant increase in power and a drastic reduction in emissions and fuel consumption compared to the locomotives it is replacing. In electric mode, the locomotive will draw power from a 750-volt DC third rail system. A key design feature of the SC-42DM is its ability to operate using both the LIRR's over-running third rail and Metro-North's under-running third rail, making the fleet adaptable to both networks.