(a)
In general— The Administrator of the Pipeline and Hazardous Materials Safety Administration shall act on any petition for regulatory action, including petitions for reconsideration of a rule and petitions from groups with delegated authority, not later than 18 months after such petition is received by the appropriate agency.
(b)
Effect of department action— Any action taken by the Secretary of Transportation or the Administrator of the Pipeline and Hazardous Materials Safety Administration, in response to a petition described in subsection (a) shall supersede any decision regarding the issue reached by a group with delegated authority.