MBTA approved the purchase of 20 HSP46s in 2010 in a deal worth $US 114m, which was MBTA's first order for new locomotives in 20 years. A further order for seven units was placed in 2012, and an option for 13 locomotives was exercised in June this year, taking the total order to 40 units.
The 3.5MW locomotives will be equipped with 12-cylinder Gevo engines from GE and will be compliant with US Environmental Protection Agency (EPA) Tier 3 emissions standards. GE will also supply static converter head-end power systems, computer control systems, and individual-axle ac traction motors.
All of the locomotives ordered by MBTA will be assembled at MotivePower's plant in Boise, Idaho.