Railroad Trains for the Soul: MPXpress Commuter Locomotives

The MPXpress diesel-electric locomotives are some of the most reliable North American commuter carriers that began production in the early 2000's. MotivePower Industries (MPI), which became a division of Wabtec, began offering commuter rail locomotives that can comply with more stringent crashworthiness standards as well as the Tier 1 exhaust emissions standards beginning in 2002. Prior to that year, Electro-Motive (EMD) and General Electric ceased production of their passenger diesel models such as the F59PHI and the P42DC, due to their lack of compliance with those modern regulations. MPI had designed four primary models of the MPXpress series: the 3,600-horsepower MP36PH-3S and MP36PH-3C, the 4,000-hp MP40PH-3C, and the 5,400-hp MP54AC. Additionally, the builder developed a rebuild program called the MP32PH-Q only for Florida's SunRail system.

The first three types are propelled by the 16-cylinder, two-cycle diesel engines that were originally designed by EMD. The -3S units use a static inverter for head-end power (HEP) while the -3C units use an independent Caterpillar HEP diesel-generator set. Ironically, the 645F prime mover for the MP36PH was redesigned and manufactured by GE, as covered in the February 2003 issue of Trains Magazine. This engine initially suffered its mechanical problems that once plagued the infamous SD50 freight locomotives from the 1980's. As a result, EMD discontinued production of the 645F and replaced it with the more powerful and reliable 710G engine, which is used for another MPXpress model: the MP40PH.

The MP36 met the Tier 1 and 2 emissions regulations between 2002 and 2011 whereas the MP40 complied with the Tier 2 and 3 standards between 2007 and 2014. However, neither of these models can possibly meet the current Tier 4 regulations, so MPI developed a new locomotive type called the MP54AC, which features a pair of Cummins QSK60 V16 engines (each rated at 2,700 hp) and four AC traction motors. This model can be built as a new unit or as an upgrade to an existing unit. GO Transit is currently the only owner of the MP54AC's, which are alternatively named MP40PHT-T4AC because their engines provide 4,000 hp for the traction motors and 1,400-hp for the train's electricity. MPI received one of GO Transit's existing MP40's (No. 647) to convert it into the Tier 4 locomotive by swapping out the EMD 710 prime mover as well as the HEP generator set for the two Cummins engines and the HEP inverter. Although the MP54 model includes AC traction, No. 647 still utilizes its existing DC motors after the conversion. Despite the option to rebuild MP40's into MP54's, GO Transit chose to order these Tier 4 locomotives built as new ones instead.

While the MP54AC is still in Wabtec's passenger locomotive catalog, there have been no recent plans from any railroad to purchase additional units; not even from GO. In 2020, however, an MP54 (No. 678) was sent to Erie, Pennsylvania for testing and familiarization purposes at the former GE Transportation factory. Regardless of their ages, the MPXpress diesels have been the best selling commuter locomotives in the United States and Canada since 2003. Some may eventually be overhauled to last longer and even increase their reliability for many more years of service. Please stay tuned for the next blog post with a separate video of GO Transit No. 678 testing in Erie.