Total intermodal freight volumes climbed 7.2% year-over-year in the first quarter of 2018, the strongest gain since the second quarter of 2014, according to new figures released by the Intermodal Association of North America.

The group, which represents the combined interests of the intermodal freight industry, also reported containers increased 6.2%, international intermodal volumes moved up 7%, and trailers led overall growth at 14.5% during the first quarter compared to the same time a year earlier.

"Drivers for first-quarter growth were an overall strong economy, the continued growth of imports, higher fuel prices, tight over-the-road capacity, and weak comparisons to lower 2017 volumes in some markets," said Joni Casey, president and CEO of IANA.

The seven highest-density trade corridors accounted for 62.8% of total volumes and were collectively up 6.2%.

The Northeast-Midwest performed the best of the seven, with volumes gaining 12.3%. The South Central-Southwest followed with 8%. The trans-Canada, intra-Southeast and Midwest-Southwest lanes had growth of 6.7%, 6.5% and 5.6%, respectively, while the Southeast-Southwest managed 2%. Only the Midwest-Northwest experienced a decline, 4.8% – its fourth consecutive quarterly loss.

Intermodal service providers had another strong quarter, though slower than the previous quarter, with total loads rising 10.8%, mostly on highway gains. Revenue grew by 27.1% in the first quarter of 2018 compared to the 27.9% growth in the fourth quarter of 2017.

The full report is available on request from IANA.

Related: Record Year for Intermodal Containers at Nation's Largest Ports