The new diesel locomotives are gradually being rolled out on Amtrak's state-sponsored services from Chicago to destinations in Illinois, Wisconsin and Michigan, and between St Louis and Kansas City, which cumulatively served 2.6 million passengers last year. Delivery is set to be completed by January 2018.

Powered by Cummins 3.2MW QSK95 diesel engines, the locomotives are able to operate at up to 200km/h and will offer significantly improved acceleration and braking as well as reduced maintenance. The engines are fitted with Selective Catalytic Reduction (SCR) exhaust after treatment, enabling the units to meet US Environmental Protection Agency Tier 4 emissions standards. They will also reduce emissions by 90% and fuel consumption by up to 16% compared with the previous locomotives used on Midwest routes.

The units, which were built at Siemens' Sacramento plant, were purchased with the support of $US 216.5m in federal funds and are part of a programme of improvements to Midwest passenger services, which includes various track improvement projects, and line enhancement between Chicago and St Louis, and Chicago and Detroit. These projects have increased the maximum operating speed on the lines to 177km/h.