This rulemaking would, establish new requirements, and revise existing requirements, in three main subject areas: (1) requirements generally applicable to all passenger equipment, such as safety appliance requirements, and pre-revenue compliance documentation and testing; (2) requirements specific to Tier I passenger equipment, such as evaluation criteria for Tier I-compliant vehicles equipped with additional crash energy management features; and (3) requirements specific to Tier III passenger equipment, such as establishing standards for the inspection, testing, and maintenance of Tier III equipment and applying the general safety requirements from 49 CFR part 229 (Railroad Locomotive Safety Standards) to Tier III equipment.