Rail Runner MP36PH-3C in New Mexico
MPXpress is a series of diesel-electric passenger train locomotives designed for commuter rail service. The manufacturer, Motive Power (Wabtec), offers the locomotives with a number of customizable options such as different prime movers and traction motors, Head-end power (HEP) generated by a separate engine or by the prime mover, and new or refurbished trucks. To date, MPI has offered five main variants: MP36PH-3S, MP36PH-3C, MP40PH-3C, MP32PH-Q, and MP54AC.
The MPXpress line of locomotives were the first production passenger locomotives to meet EPA Tier 1 and Tier 2 emissions regulations, as well as FRA safety regulations regarding crashworthiness and fire safety. The line also meets APTA crashworthiness standards.
Numerous public transit agencies in Canada and the United States have ordered MPXpress locomotives for their commuter rail services. GO Transit is the largest client for MPI MPXpress locomotives with 67 in their fleet.
The MP36PH-3S uses a 16-cylinder EMD 645F3B diesel engine as its prime mover. Its HEP is generated from a static inverter that receives its power through connections to the prime mover — hence the "S" (static) designation. When providing full electrical power to the passenger cars connected to it, the prime mover must maintain a higher RPM in order to supply power to the passenger cars. The traction power when providing full HEP load of 500 kW is 2930 HP, since HEP generation diverts some power from the prime mover.
Chicago's Metra ordered 27 of these locomotives, which were built and delivered between 2003 and 2004. Fourteen were to replace Metra's aged F40C fleet, while the rest were for expansion. When the locomotives were first delivered, they exhibited software and computer problems, to the point that Metra had to put two F40Cs back into service for a short time in 2004. One of the unique features of the MP36s in Metra's fleet compared to other operators is that they are equipped with a Gyralite (which is standard equipment on all of Metra's passenger locomotives), which are mounted in the spot on the front of the locomotive where the locomotive number board would otherwise be located. Metra is currently the only operator of the MP36PH-3S version.
Metra has plans to convert all of their MP36PH-3S locomotives to the MP36PH-3C specification by removing the static inverter system and replacing it with an HEP genset in an effort to reduce noise pollution and boost fuel efficiency. As of August 2015 the first -3C Conversion has taken place with Metra 417 returning from the MPI's Shops in Boise, ID for testing. 
The MP36PH-3C has the same prime mover as the "-3S" model, the EMD 645F3B diesel engine, but with its HEP generated by a separate Caterpillar C-27  diesel engine, thus the "C" in its model name. In this arrangement, when providing HEP, the full 3600 HP from the prime mover is available for traction, and the prime mover is allowed to idle at a lower RPM. The Wabtec Q-Tron control system is used in all models built prior to 2008/9, while newer units use the same EM2000 system like GO Transit's MP40PH-3C. Caltrain was the first to purchase the MP36PH-3C in 2003.
The MP40PH-3C is similar to the MP36PH-3C, but with several differences:
- the MP40PH-3C uses a 16-cylinder EMD 710GB series diesel engine instead of the EMD 645F3B, generating 4000HP instead of 3600.
- the use of EMD's EM2000 computer and associated control system instead of Wabtec/MPI's own system in the MP36.
- the use of an EMD alternator and traction motors.
GO Transit ordered 27 locomotives of this model to replace their aging EMD F59PH fleet, which were delivered throughout 2007 and 2008. An order for 20 additional units was signed in July 2008. In February 2010, yet another order was signed for 10 additional units. It was announced on November 1, 2011 that GO Transit would be swapping out the EMD prime movers of 11 MP40s for the new Cummins QSK95. However, later on it was decided that two QSK60s would be installed in lieu of the QSK95. This eventually became the MP54AC. The original plan was to convert an additional 10 locomotives. However, this plan has since been dropped and GO has opted to purchase 16 new locomotives instead.
The MP32PH-Q was built for SunRail to similar specifications as new MPXpress locomotives, but are refurbished from units that had previously operated on MARC as GP40WH-2 locomotives. Inside the locomotive, the engines have been rebuilt and electronics have been upgraded using the same equipment as other MPXpress locomotives. On the outside the MP32PH-Q retains the hood unit layout of the GP40WH-2, but with a new MPXpress cab.
GO Transit was the launch customer for the MP54AC, a higher performance AC traction locomotive that could meet Tier IV standards in the United States and compete with the EMD F125 and Siemens Charger. MPI used an existing MP40PH-3C from GO Transit (Unit 647), and replaced the EMD engine with a pair of Cummins 16-cylinder QSK60 engines rated at 2,700 hp each (5,400 hp total), making it the most powerful diesel passenger locomotive in North America. Heavy modifications were made to the body to accommodate extra air intake and exhaust stacks. Unit 647 was delivered to GO Transit late 2015 and was seen under testing on December 12, 2015. 
|Caltrain||San Francisco, California||MP36PH-3C||6|
|FrontRunner||Salt Lake City, Utah||15|
|MARC||Washington, D.C./Maryland/West Virginia||26|
|Metrolink||Los Angeles, California||15|
|New Mexico Rail Runner Express||Albuquerque, New Mexico||9|
|Northstar Line||Minneapolis, Minnesota||6|
|Virginia Railway Express||Washington, D.C./Virginia||20|
|West Coast Express||Vancouver, British Columbia||1|
|GO Transit||Toronto, Ontario||MP40PH-3C||66|
|Sounder Commuter Rail||Seattle, Washington||MP40PH-3C||3|
|SunRail||Greater Orlando, Florida||MP32PH-Q||10|
- "Locomotives". LTK Engineering Services. Archived from the original on September 7, 2014.
- "Metra Proposed 2013 Program and Budget". Metra. November 2012. Archived from the original (PDF) on September 7, 2014.
- Lex, Robert (29 September 2013). "Northstar Commuter Rail MP36PH-3C Parts". Parts List for MPXpress locomotives.
- Cummins to produce Tier 4 compliant diesel engine - Railway Gazette
- "SunRail, Sound Transit order MotivePower locomotives". Trains. September 12, 2011. Retrieved September 13, 2011.
- Murdock, Ken (April 2014). "Winter Park’s Station Dedication". The Flatwheel 3–5. Archived from the original (PDF) on September 7, 2014.
- "MP54 AC COMMUTER LOCOMOTIVE". Wabtec Corporation. Retrieved 2015-12-16.
- "First MP54AC testing on GO Transit". Railway Age. Retrieved 2015-12-16.
|Wikimedia Commons has media related to MPI MP36PH-3S locomotives.|
|Wikimedia Commons has media related to MPI MP36PH-3C locomotives.|
|Wikimedia Commons has media related to MPI MP40PH-3C locomotives.|
|Wikimedia Commons has media related to MPI MP32PH-Q locomotives.|
- MP54AC Brochure and Spec Sheet
- MPXpress Commuter Locomotives Brochure and Spec Sheet
- MBTA MP36PH-3C Operator's Manual
- MP40PH-3C Tractive Effort and Dynamic Brake effort curve; Page 3