A labor dispute between CSX Transportation and its unions could affect commuter rail service in Maryland. CSX has notified Maryland transportation officials that union members could go on strike Friday morning. That would effectively shut down MARC commuter train service on the Camden and Brunswick lines since CSX owns and maintains those lines. The Maryland Transit Administration is recommending that passengers using those trains make alternate travel plans in case there is a strike. Penn Line service would not be affected and will operate as scheduled.