(AP) — The Obama administration moved Wednesday to significantly expand a requirement for utilities to install inexpensive safety valves on gas lines across the U.S. after deadly fires and explosions going back decades that could have been avoided. The Transportation Department proposal would cover new or replaced natural gas lines serving multi-family dwellings, small businesses and homes not already covered under a 2009 mandate. Fire Capt. David Wells led the first company responding to the scene of a gas explosion in Springfield, Massachusetts, in November 2012 that injured at least 20 people and damaged dozens of buildings with a boom heard for miles. Industry representatives previously have raised concerns about the potential cost of installation, particularly for larger gas lines that would require specialized valves. Transportation officials said the proposal was nevertheless justified because of hard-to-measure benefits, such as avoided evacuations, environmental damages and the possibility of a high-consequence incident that could inflict mass casualties. The proposal would expand that to include lines serving multiple homes, duplexes and small multi-family buildings, and shops ranging from doctors’ offices and shopping centers to banks.