From railway safety act introduced Mar.1 https://www.congress.gov/bill/118th-congress/senate-bill/576/text#toc-idd825ba661275482da62d9f968401614b
On March 1 US Congress introduced a bill for railway safety act, of interest is:
SEC. 5 Defect Detectors
(a) Rulemaking.—Not later than 1 year after the date of the enactment of this Act, the Secretary shall issue regulations establishing requirements for the installation, repair, testing, maintenance, and operation of wayside defect detectors for each rail carrier operating a train consist carrying hazardous materials.
(b) Requirements.—The regulations issued pursuant to subsection (a) shall include requirements regarding—
(1) the frequency of the placement of wayside defect detectors, including a requirement that all Class I railroads install a hotbox detector along every 10-mile segment of rail track over which trains carrying hazardous materials operate;
(2) performance standards for such detectors;
(3) the maintenance and repair requirements for such detectors;
(4) reporting data and maintenance records of such detectors;
(5) appropriate steps the rail carrier must take when receiving an alert of a defect or failure from or regarding a wayside defect detector; and
(6) the use of hotbox detectors to prevent derailments from wheel bearing failures, including—
(A) the temperatures, to be specified by the Secretary, at which an alert from a hotbox detector is triggered to warn of a potential wheel bearing failure; and
(B) any actions that shall be taken by a rail carrier upon receiving an alert from a hotbox detector of a potential wheel bearing failure.
(c) Defect And Failure Identification.—The Secretary shall specify the categories of defects and failures that wayside defect detectors covered by regulations issued pursuant to subsection (a) shall address, including—
(1) axles;
(6) other defects or failures specified by the Secretary.