49 C.F.R. § 670.25 – General directives.

(a) General. The Administrator may issue a general directive under this part that is applicable to all recipients or a subset of recipients for the following reasons—
1. (1) The Administrator determines that an unsafe condition or practice, or a combination of unsafe conditions and practices, exists such that there is a risk of death or personal injury, or damage to property or equipment; or
2. (2) For any other purpose where the Administrator determines that the public interest requires the avoidance or mitigation of a hazard or risk.
(b) Effective date. A general directive is effective upon final notice provided by the Administrator under paragraph (e) of this section.
(c) Notice. The Administrator will provide notice of a general directive to recipients in the Federal Register. The notice will include at minimum—
1. (1) A reference to the authority under which the directive is being issued;
2. (2) A statement of the purpose of the issuance of the directive, including a description of the subjects or issues involved and a statement of the remedial actions sought; and
3. (3) A statement of the time within which written comments must be received by FTA.
(d) Consideration of comments received. The Administrator will consider all timely comments received. Late filed comments will be considered to the extent practicable.
(e) Final notice. After consideration of timely comments received, the Administrator will publish a notice in the Federal Register that includes both a response to comments and a final general directive or a statement rescinding, revising, revoking or suspending the directive.