Norfolk Southern Corp. said its quarterly profit will fall short of analysts’ estimates as volumes dwindle at the second-largest Eastern US railroad. The rest of the North American industry also slumped on concern that the decline in shipments adds to evidence that the US economic recovery is losing steam. Volume at Norfolk Southern will decline about 2 percent in the third quarter to 1.78 million carloads, with coal dropping 13 percent and general merchandise down 1 percent, the Norfolk, Va.-based railroad said. ‘‘The summer drought has dramatically changed the landscape of the US grain market,’’ chief financial officer John Rathbone said. Quarterly profit will be $1.18 to $1.25 a share, the company said. That’s short of the $1.63- a-share average estimate of analysts.