FRA is proposing to amend its regulations for passenger equipment safety standards, which currently provide for passenger rail service in a shared right-of-way under two separate tiers of safety standards: Tier I (speeds up to 125 miles per hour (mph)) and Tier II (speeds up to 150 mph) . Consistent with the regulations' approach supporting interoperable passenger rail service by sharing the right- of-way, this proposed rulemaking would add a new tier of safety standards (Tier III) to facilitate the safe implementation of interoperable high-speed passenger rail service at speeds up to 220 mph. However, Tier III standards would require operations at speeds above 125 mph to be in an exclusive right-of-way without grade crossings. The proposal also would establish crashworthiness and occupant protection performance requirements in the alternative to those currently specified for Tier I passenger trainsets. Adopting the proposed alternative crashworthiness and occupant protection requirements would remove regulatory barriers, allowing a more open U.S. rail market, incorporating recent technological designs. In addition, the proposal would increase from 150 mph to 160 mph the maximum speed FRA's existing regulations allow for passenger equipment that complies with FRA's Tier II standards.