Norfolk Southern NS LogoNORFOLK, Va (AP) _  Norfolk Southern Corp.’s first-quarter profit fell 18 percent as severe winter weather slowed shipments and the railroad delivered 1 percent less freight overall.The Norfolk, Virginia, based railroad said Wednesday it earned $368 million, or $1.17 per share, during the January-March period. That’s down from $450 million, or $1.41 per share, a year ago.  “Following the extreme winter weather across the U.S. rail network which impacted first-quarter results, we are seeing a rebound in shipments across all of our business,” Norfolk Southern CEO Wick Moorman wrote in a statement. “Our people responded admirably to meet the challenges of the harsh conditions, and we remain focused on delivering superior service to our customers.”  Declines in automotive, construction and forest product shipments offset increases in crude oil and liquefied petroleum gas shipments.