; or (B) results in the shutdown of gas service to more than 100 customers; and (3) the development and implementation of a voluntary, opt-in system that would allow operators of distribution pipelines to rapidly communicate with customers in the event of an emergency. . 4. Operations and maintenance manuals Section 60102 of title 49, United States Code (as amended by section 3), is amended by adding at the end the following: (r) Operations and maintenance manuals Not later than 1 year after the date of enactment of this subsection, the Secretary shall promulgate regulations to ensure that each procedural manual for operations, maintenance, and emergencies under section 192.605 of title 49, Code of Federal Regulations (or successor regulations), developed by an operator of a distribution pipeline includes written procedures for— (1) responding to overpressurization alarms, including a clear timeline and order of operations for shutting down portions of the gas distribution system, if necessary