Amtrak ordered fifteen HHP-8 locomotives in 1999. These engines featured 8,000 horsepower engines, making them the most powerful in Amtrak's fleet. However, they were plagued with mechanical issues throughout their history and retired in November 2014 after just 15 years in revenue service.
HHP-8 651 at BWI Airport Rail Station, April 2, 2014
HHP-8 655 at 30th Street Station, Philadelphia, PA, June 27, 2001
HHP-8 661 passing Newark Liberty Airport Station in Newark, NJ, April 15, 2011