sharp decline in the mechanical reliability of the EMD SDP40F, including several derailments. The second was the unusually harsh winter of 1976–1977, which sidelined many of Amtrak's aging steam-heated coaches. Amtrak suspended numerous routes and pressed the new HEP-equipped Amfleet I coaches, designed for short runs, into service. The F40PH, with its built-in HEP generator, was the natural choice to haul these trains. As problems with the EMD SDP40F mounted, Amtrak adopted the F40PH as its long-term solution nationwide for diesel service. In the spring of 1977 Amtrak traded 40 SDP40Fs back to EMD; components including the prime mover were installed into an F40PH's frame. The 40 rebuilt locomotives were designated F40PHR and were identical to new-build F40PHs, incorporating the larger fuel tank and more powerful HEP generator which had become standard. Amtrak ultimately acquired 132 F40PHRs in this manner, which combined with new orders between 1975 and 1988, and the purchase of six GMD F40PHs from GO Transit in 1990, led to a fleet of 216 locomotives, the country's largest fleet. The first commuter rail operator to order F40PHs was Chicago's Regional Transportation Authority (RTA), a forerunner to Metra, who ordered 74 between 1977 and 1983. Metra ordered 41 more between 1988 and 1992. Other agencies who bought the F40PH included the Massachusetts Bay Transit Authority (MBTA) (18), Caltrain (20), GO Transit (6), New Jersey Transit (17), and Via Rail (59). Finally, the rail construction firm Speno ordered four. In total EMD built 449 locomotives, including the F40PHR trade-ins. The F40PH performed well for Amtrak; at the start of the 1990s only four had been retired due to wrecks and the locomotive was at the center of Amtrak's advertising. Trains magazine estimated that on average, each F40PH traveled as many as a year. Amtrak began replacing the F40PH with the GE Dash 8-32BWH in 1991, the GE P40DC in 1993 and the GE P42DC in 1996. All were retired by 2001 with the arrival of the last P42DC and their last regular assignment was on the Maple Leaf in December 2001. The Panama Canal Railway acquired several ex-Amtrak F40PHs for both freight and passenger service; the 480V head-end power matched the voltage used by the refrigeration in Maersk Sealand containers. The F40PH has continued to serve Via Rail into the 21st century; between 2007 and 2012 Via refurbished its entire fleet for CAD $100 million. The rebuild program included