Railroad Trains for the Soul: AC Traction Rebuilds
In the previous blog post, we've talked about the 1990's-era DC traction diesel locomotives rebuilt into more reliable AC locomotives. However, even the as-built AC diesels are no exception to modernization. These include the EMD SD70MAC and SD90MAC as well as the GE AC4400CW and AC6000CW. We'll start with the EMD programs.
In 2014, Norfolk Southern purchased 100 convertible SD9043MAC locomotives from Union Pacific via EMD. Later, ten more units were bought from CIT Group (CEFX). They were all powered by the as-delivered 4,300-horsepower 16-cylinder 710G diesel engine, which could have been replaced by the 6,000-hp 265H V16 engine; the conversion never happened. Instead, NS was going to develop a modernization program to rebuild these locomotives into SD70ACe specifications with the most advanced technology available in the market. This resulted in the new model name: the SD70ACU (U for "upgraded"). The first SD70ACU diesels were rebuilt at the railroad's Juniata Shops in Altoona, Pennsylvania and debuted in 2016. As of this blog post, all of the SD90's have been modernized for NS. Canadian Pacific is the next customer of the 70ACU program as Progress Rail announced in 2018, so the first four rebuilt units were completed by the next year. Since then, there are 15 notable examples painted in commemorative liveries: five in the veterans schemes and ten in CP's old-style tuscan red and gray heritage schemes. Between NS and CP, all copies of the SD70ACU can be identified by the new ACe-style cab fixed to the rest of the 90MAC body.
The EMD SD70MAC is another acceptable type for modernization and can also be upgraded into SD70ACe specs. For that reason, the new model name is the SD70MACe. One of the most important upgrades for these locomotives is the new electrical control equipment manufactured by Mitsubishi; the older equipment was originally made by Siemens for many 1990's-era EMD AC diesels. The same improvements are true to the SD70ACU rebuilds. The SD70MACe is rostered by three Class I railroads: BNSF, Kansas City Southern, and CSX. Interestingly, Metra is seeking to acquire a fleet of EMD AC rebuilds in an effort to reduce air pollution in the Chicago area. Classified as the SD70MACH, the locomotives will be Tier 3 emissions-compliant and equipped with head-end power for the passenger cars. The first SD70MACH units will be completed by 2021 at the earliest.
GE soon became involved in the AC locomotive rebuild business with CP being the first client. The railroad sent the first AC4400CW diesel to be modernized at the builder's Erie, Pennsylvania factory in 2017. Numbered 8100, the locomotive is the first rebuilt GE unit to be called AC4400CWM. While running on the builder's test track, the CP AC4400CWM was initially seen with the front half of its body unpainted, suggesting that a new operator's cab and a more advanced electrical compartment were installed. However, when these rebuilds are fully painted, they can possibly be spotted by the front door moved to the opposite side of the nose as seen on most of the GE Evolution Series locomotives. The purpose of the AC44CWM program is to upgrade them with the latest technology that matches the performance of the GE ES44AC while keeping the 16-cylinder 7FDL diesel engine onboard.
The Union Pacific likewise decided to modernize some of its existing AC locomotives built by GE, especially the convertible AC4400/6000CW (or C6044AC). Equipped with the 4,400-horsepower 7FDL-16 engine, the convertibles originally had the option to be repowered by the 6,000-hp 7HDL-16 diesel. However, the C6044AC units were never re-engined, just like the EMD SD9043MAC, but they can be converted to the same level of technology as in the Evolution Series. Unlike the CP AC44CWM, the UP rebuilds only have the new electrical compartment installed but keep all the other parts unchanged, including the operator's cab. Union Pacific also has some of its regular AC4400CW (C44AC) locomotives upgraded with only the remanufactured auxiliary section as the most visible change. Once rebuilt, both the C44AC and C6044AC are reclassified as C44ACM by the railroad.
CSX sent its first CW44AC to be modernized by GE in 2019. Prior, the railroad initially modified some of its AC44's with high-adhesion software and reclassified them as CW44AH. Because the rebuild program involves the standard and heavy versions of these locomotives, CSX assigns two separate classes: CM44AC (numbered in the 7000-series) and CM44AH (7200-series). The former can be spotted by the Hi-Ad trucks while the latter contains steerable trucks. Like the Canadian Pacific rebuilds, the remanufactured CSX units otherwise have the new operator's cab and auxiliary compartment onboard, and they also have the nose door relocated.
According to Trains Magazine's Locomotive 2020 issue, rebuilt locomotives from both EMD and GE have outsold new ones since 2018. The controversial Precision Scheduled Railroading business practice is probably one of the reasons for the reduction of demand for Tier 4 diesels. Nonetheless, the two large builders have still made good revenue by offering modernization programs, including those for existing AC traction locomotives.
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