CSX Corp., the biggest railroad in the eastern U.S., reported second-quarter profit that beat analysts’ estimates as shipments of chemicals such as crude oil increased.

Net income rose 4.5 percent to $535 million, or 52 cents a share, from $512 million, or 49 cents, a year earlier, CSX said Tuesday in a statement. That surpassed the 47-cent average of 28 estimates compiled by Bloomberg.

CSX benefited as it carried 11 percent more chemical carloads, helped by oil and gas drilling in shale formations. The Jacksonville, Florida-based company had beaten or matched profit expectations in 15 of the previous 17 quarters, according to data compiled by Bloomberg, as the economy strengthened and Chief Executive Officer Michael Ward boosted efficiency.

“The company has been outperforming our traffic growth assumptions,” a sign that second-quarter results would be solid, Jason Seidl, an analyst at Cowen & Co. in New York who rates CSX shares market perform, wrote in a note to clients before the announcement.

Sales rose 1.9 percent to $3.07 billion, exceeding the $3.03 billion average estimate. Total shipments rose 1 percent, including gains of 8.9 percent for phosphates and fertilizers as a customer mine reopened and 7.1 percent for minerals such as stone and gravel as construction recovered, CSX said.

The volume of coal, the company’s largest individual cargo category, dropped 6.3 percent, narrowing from a 10 percent decline in the first quarter.

Operating Ratio

Operating ratio, an industry gauge of expenses to revenue, fell to 68.6 percent from 70.4 percent in the first quarter and 68.7 percent a year earlier. CSX in April pushed back a goal of lowering its ratio to 65 percent by 2015, in favor of a “high 60s” target with additional reductions later.

Profit per share this year will be “roughly flat” versus 2012, CSX said today. The company’s earlier forecast was for those earnings to be little changed to “slightly down.”

CSX rose 1.7 percent to $25.05 in extended trading at 4:54 p.m. in New York. Earlier, the shares closed at $24.64, an increase of 1.2 percent. They have gained 25 percent this year, as the Standard & Poor’s 500 Index advanced 18 percent.