Here's the summary of the pertinent part of PRIAA:------------------------------------------
Rail Passenger Service Quality
FRA and Amtrak, in consultation with the Surface Transportation Board (STB), Amtrak’s host railroads, States, Amtrak’s labor organizations, and rail passenger associations are to develop metrics and minimum standards for measuring the performance and service quality of intercity passenger train service [§207]. FRA is to publish quarterly reports on a variety of performance and service quality factors including cost coverage, train delays, and on-board services. STB may investigate on its own initiative or upon receipt of a complaint from Amtrak, an intercity rail passenger operator, a host freight railroad over which Amtrak operates, or an entity for which Amtrak operates intercity passenger rail service of poor on time performance or other service quality deficiencies of intercity passenger rail based on the new standards to determine whether and to what extent delays or failure to achieve minimum standards are due to causes that could reasonably be addressed by the host freight railroad, Amtrak or other intercity passenger rail operators [§213]. If the STB determines that delays or failures to achieve minimum standards are attributable to a rail carrier’s failure to provide preference to Amtrak over freight transportation, it could award damages to be paid by the host freight railroad to Amtrak or the service sponsor. The awarded damages would be used by Amtrak or the service sponsor for capital or operating expenditures on the route to help achieve the minimum standards. The STB will set up its process for receiving and addressing complaints. Following issuance of the metrics and standards, Amtrak is to develop and implement a plan to improve on-board service in accordance with the metrics and standards [§222].
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Admittedly it's just the summary, but I don't see that it empowers Amtrak to do anything more than participate in setting up the rules. STB is clearly given the responsibility to decide if the RR's have misbehaved.
And, don't the existing contracts already allow for penalties?