General contractor Joseph B. Fay Co. and the Pennsylvania Dept. of Transportation said they would work around the clock to repair a bridge-truss compression cord damaged during renovation work on a bridge. A welder’s torch ignited tarps and plastic pipes during work on Sept. 2, prompting officials to shut the Liberty Bridge, which carries a key artery into Pittsburgh. The contractor, which called the fire an “unfortunate incident,” faces potential damages of $213,000 for each day the bridge is closed.