April 23 (Reuters) - U.S. railroad operator Norfolk Southern (NSC.N), reaffirmed its annual forecast after topping first-quarter revenue estimates on Wednesday, on the back of increased volume in intermodal freight transport.

Shares of the Atlanta, Georgia-based company rose as much as 4%.

Container imports to the United States hit record highs in January and February as companies rushed to bring in goods early in the year fearing price hikes from President Donald Trump's sweeping tariffs, which helped intermodal volume at railroads such as Norfolk Southern.

Norfolk's revenue from intermodal shipping, which involves transporting goods via two or more means of transportation, was up 2% from a year earlier at $760 million.

"The network is operating with more resiliency than peer CSX (CSX.O), and we expect Norfolk will be one of the few in the sector that reiterates forecast," said JP Morgan analyst Brain Ossenbeck.

However, on a post-earnings call, Norfolk said it expects volume to take a hit the rest of the year due to the tariffs.

Norfolk also said its insurance recoveries related to a derailment in Eastern Ohio in 2023 exceeded expenses by $185 million in the quarter.

Excluding fuel surcharges, the company reported operating revenue of $2.79 billion for the quarter, up 1.71% from a year earlier.

Fuel surcharges are added fees the company collects from customers to account for fluctuations in the price of fuel used to operate trains.

Norfolk reported an adjusted operating ratio, a key profitability metric, of 67.9%, a 200-basis-point improvement from a year earlier.

Total revenue for the quarter was $2.99 billion, compared with average analysts' estimate of $2.98 billion according to data compiled by LSEG.

The company reported an adjusted profit of $2.69 per share for the reported quarter, in line with analysts' estimates.