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Notice of availability and request for comments.

This document provides the public with notice that on August 22, 2021, CSX Transportation (CSX) submitted its Test Request for Trip Optimizer Air Brake Control (TO Air Brake Control), Revision 1, dated August 22, 2021, to FRA. CSX asks FRA to approve its Test Request so that it may test its TO Air Brake Control on track that has been equipped with positive train control (PTC).

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