The agency first issued the rule in the Federal Register on September 2 and provided a December 1 deadline. That has now been extended to December 15.

A public inspection of the extension will be available in the Federal Register on November 25.

As proposed, proximity systems would be required on all coal haulage equipment in underground coal mines, including shuttle cars, ram cars and scoops.

Operators, MSHA said, will have to install proximity systems that cause a coal-hauling machine or scoop to stop before contacting a miner; provide audible and visual warning signals when a miner gets too close to the machine (within the machine’s warning zone); provide a visual signal on the machine that indicates the system is functioning properly; prevent movement of the machine if the system is not functioning properly; prevent interference with or from other electrical systems; and be installed and maintained by a person trained in the system’s installation and maintenance.