CHARLESTON, W.Va. -- Under pressure from a lawsuit, members of a state board spent Thursday morning working through a long list of questions about requiring coal operators to install technology that would save workers from being crushed by underground mining equipment.Board of Coal Mine Health and Safety members again did not complete work on a proposed rule, putting off several key decisions about the "proximity detection" technology until another meeting next week.Among other things, board members remain unsure of exactly what timeline they might use for requiring the devices on different sorts of underground mining equipment.One draft discussed at Thursday's meeting would have mandated the safety devices on new continuous mining machines by July 1 of this year, and on any rebuilt continuous miners by July 1, 2015. The draft would also have required either proximity devices or cameras on other types of underground machines, such as scoop vehicles, within two years.But board member Chris Hamilton, a vice president of the West Virginia Coal Association, suggested that perhaps the rule should provide different timelines for different sizes of mining companies. Some operators might have two or three machines that need proximity detection, Hamilton said, while others might have 30 or 40 machines to retrofit."I'm not sure it's fair to have one date for both companies," Hamilton said.And board member Charles Russell, a representative of Arch Coal, said the board needs to carefully consider what other equipment -- besides continuous miners -- would be required to have proximity detection."I think it should be on all equipment that goes underground," said Carl Egnor, a United Mine Workers representative on the board.Terry Hudson, a board member from Patriot Coal, said that the rule needs to be written in a way that allows mine operators to avoid flooding equipment-rebuilding shops with more work than they can manage. Hudson said the two-year deadline for equipment other than continuous miners "appears to be a little too aggressive."Hudson said the issue needs to be on the "fast track," but "I'm just trying to be realistic about getting this all done."Board members discussed the issue as the state Supreme Court considers an emergency petition filed by the public interest law firm Mountain State Justice on behalf of a coal miner and a miner's widow who allege inaction by the board and the state Office of Miners' Health, Safety and Training.The suit says the agencies should have long ago mandated the use of proximity detection systems to protect miners from being crushed or pinned by fast-moving underground machines.Attorney General Patrick Morrisey, representing the mine safety board, has sought to have the case dismissed.Board members referred to Thursday's meeting as a "subcommittee" meeting, even though all six board members participated. Another meeting of the full board is scheduled for Jan. 16, and Morrisey's office predicted in a court filing that the board could complete a rule by then.Meanwhile, the U.S. Mine Safety and Health Administration said Thursday that it had forwarded a final version of a national rule for proximity devices on continuous mining machines to the White House for Office of Management and Budget approval.But, MSHA also withdrew a second, draft proposed rule to require proximity detection on other types of mining equipment.Amy Louviere, an MSHA spokeswoman, said that the technology is advancing and that the Department of Labor, MSHA's parent agency, temporarily withdrew the proposal "to make refinements consistent with technological advances."Reach Ken Ward Jr. at firstname.lastname@example.org or 304-348-1702.