NORFOLK, 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. Last year’s results were helped by a one-time $60 million real estate gain that boosted profits by 19 cents per share. Norfolk Southern says revenue declined 2 percent to $2.69 billion. Analysts expected $2.739 billion. Declines in automotive, construction and forest product shipments offset increases in crude oil and liquefied petroleum gas shipments.