* 2nd-qtr net profit $1.79/shr vs est $1.74
* Revenue rises 8.6 pct to $3.04 bln
* Total volume rises 8 pct (Adds, details, shares)
July 23 (Reuters) - 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.
Norfolk Southern's shares were up 0.8 percent at $108.43 in light trading before the bell. Up to Tuesday's close, the stock had gained about 40 percent in the past 12 months, beating the 27 percent rise in the S&P 500 railroads index. (Reporting by Ankit Ajmera; Editing by Ted Kerr)