The 200km/h ac traction F125 is equipped with a 20-cylinder four-stroke Caterpillar C175-20 engine, generating an output of 3.5MW and a starting tractive effort of 32.2 tonnes. The single-cab monocoque bodyshell was designed for EMD by Vossloh Rail Vehicles (VRV) and features a crash energy management system to absorb energy in the event of a collision. The locomotives will also be equipped with VRV high-speed running gear and inverter-controlled head-end power.

EMD says the F125 is compliant with the US Passenger Rail Investment and Improvement Act's 305-005 Next Generation Locomotive specifications and offers an 85% reduction in emissions compared with older Tier 0 diesel locomotives. This is achieved through the use of a selective catalytic converter-only aftertreatment system and electronic fuel injection.

The locomotives will be assembled at EMD's plant in Muncie, Indiana, and are due to be delivered in 2015. As part of the project, Metrolink will donate up to five existing EMD F59 locomotives for alternative fuels research and development programmes.