What are the Primary, Secondary, and Safe to Run designations for rolling stock?
Rolling stock (coaches and wagons) are usually classified into three categories for maintenance purposes. The primary maintenance category consists of vehicles that need thorough inspection and maintenance. They are to be examined closely from all aspects, and all parts that are at the limit of the prescribed running life (in km or calendar time) are to be replaced, whether or not damaged. All standard maintenance procedures are applied. The secondary category refers to vehicles that do not need such intensive examination and maintenance procedures applied; appropriate maintenance procedures are carried out, and parts are replaced only if damaged or hazardous to safety. The undergear and wheelsets are always examined. The safe to run (STR) category refers to coaches and wagons that are considered to be in good running condition and can be immediately used for scheduled services, and which require only minimal maintenance. Parts are replaced or repaired only if damaged or hazardous to s