I'm talking about the report that was required under Section 7311(b) of the FAST Act, Public Law 114-94 [1]:

  (b) Emergency Braking Application Testing.--
    (1) In general.--The Secretary shall enter into an agreement 
        with the National Academy of Sciences to--
                    (A) complete testing of ECP brake systems during 
                emergency braking application, including more than 1 
                scenario involving the uncoupling of a train with 70 or 
                more DOT-117 specification or DOT-117R specification 
                tank cars; and
                    (B) transmit, not later than 18 months after the 
                date of enactment of this Act, to the Committee on 
                Transportation and Infrastructure of the House of 
                Representatives and the Committee on Commerce, Science, 
                and Transportation of the Senate a report on the results 
                of the testing.

and the review required under 7311(c):

  (c) Evidence-Based Approach.--
            (1) Analysis.--The Secretary shall--
                    (A) not later than 90 days after the report date, 
                fully incorporate the results of the evaluation under 
                subsection (a) and the testing under subsection (b) and 
                update the regulatory impact analysis of the final rule 
                described in subsection (b)(2)(A) of the costs, 
                benefits, and effects of the applicable ECP brake system 
                requirements;
                    (B) as soon as practicable after completion of the 
                updated analysis under subparagraph (A), solicit public 
                comment in the Federal Register on the analysis for a 
                period of not more than 30 days; and
                    (C) not later than 60 days after the end of the 
                public comment period under subparagraph (B), post the 
                final updated regulatory impact analysis on the 
                Department of Transportation's Internet Web site.
            (2) Determination.--Not later than 2 years after the date of 
        enactment of this Act, the Secretary shall--
                    (A) determine, based on whether the final regulatory 
                impact analysis described in paragraph (1)(C) 
                demonstrates that the benefits, including safety 
                benefits, of the applicable ECP brake system 
                requirements exceed the costs of such requirements, 
                whether the applicable ECP brake system requirements are 
                justified;
                    (B) if the applicable ECP brake system requirements 
                are justified, publish in the Federal Register the 
                determination and reasons for such determination; and
                    (C) if the Secretary does not publish the 
                determination under subparagraph (B), repeal the 
                applicable ECP brake system requirements.

[1] https://www.govinfo.gov/content/pkg/PLAW-114publ94/html/PLAW...