In compliance with federal requirements and its ongoing commitment to safety, Amtrak routinely inspects its railcars and locomotives.  Amtrak discovered corrosion in several Horizon railcars and, while working with the manufacturer, it was decided to remove the equipment from service after learning of additional areas of concern from intensive inspections of multiple cars. The removal of this equipment from service will affect services on several routes: Downeaster, Hiawatha, Borealis, and Amtrak Cascades. Some trains, such as the Downeaster, will operate with fewer cars, while other services will be provided substitute transportation until a long-term plan is developed.  

-via Press Release