U.S. railroad operator Norfolk Southern Corp reported a better-than-expected second-quarter profit, helped by higher volumes across its businesses as the economy improves. Norfolk Southern, which joins other U.S. and Canadian railroads in reporting strong quarterly results, said overall volume rose 8 percent in the three months ended June 30 as shipments of building materials, metals and coal all rose. Coal volumes, which had been declining due to the growing availablity of cheap shale gas, rose 3 percent as rising gas prices encouraged utilities to switch back. Volumes in company's intermodal business rose 11 percent. Net income rose about 21 percent, to $562 million, or $1.79 per share, from $465 million, or $1.46 per share, a year earlier. Railway operating revenue rose 8.6 percent to $3.04 billion Analysts on average had expected earnings of $1.74 per share on revenue $3.03 billion, according to Thomson Reuters I/B/E/S. (Reuters)