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Notice of availability and request for comments.

This document provides the public with notice that on March 22, 2023, twenty host railroads submitted a joint request for amendment (RFA) to their FRA-approved Positive Train Control Safety Plans (PTCSP) reflecting the updated PTC onboard software, I-ETMS On-Board 6.5.0 and On-Board 6.5.1. This RFA includes modifications to the associated PTC Concept of Operations and PTC System Description documents, change or addition of system safety-critical functionality, modification to target safety levels and changes to the human-machine interface which requires amendments to PTC training for train crews. The functionality changes include: updates to Train Restriction Types to address the Pipeline and Hazardous Materials Safety Administration (PHMSA) final rule which restricts operating speeds of High-Hazard Flammable Train; the addition of a new system safety critical function, PTC Suspension, that prevents the generation and enforcement of targets within the limits of a PTC Suspension area with the exception of navigation failure and synchronization errors; and updates to the onboard display to show prompting to the train crew whenever a system fault related to braking prediction calculation exits. As this joint RFA involves requests for FRA's approval of the proposed material modifications to FRA-certified positive train control (PTC) systems, FRA is publishing this notice and inviting public comment on railroads' joint RFA to their PTCSPs.

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