The United States Postal Service (USPS) operates a mail processing facility in Lehigh Valley, Pennsylvania, called the “Lehigh Valley Processing & Distribution Center” (Center). A sprawling multi-component machine called an APPS (standing for “Automated Package Processing System”) occupies about 75% of the Center’s floorspace. (T. 25). On October 15, 2016, one of the many conveyor belts on the APPS broke and required repair. Employees doing the repairs were trained and experienced in controlling hazardous energy during such repairs by applying USPS’s APPS-specific procedures for the control of hazardous energy.