The American Trucking Associations' advanced seasonal adjusted For-Hire Truck Tonnage Index shrank 5.8% in September, erasing the 5% increase of the month before.

The index equaled 132.7, down from 140.8 in August and more than 12 down from the all-time high recorded in February of this year.

Compared to the same month a year ago, the index fell 0.7% for the first year-over-year decline since Oct. 2015, according to ATA.  From the beginning of the year through September, tonnage is up 3% compared to last year.

“Volatility this year continued again in September with the large drop after a significant increase in August,” said Bob Costello ATA chief economist. “The changes we’re seeing in typical seasonal trends are making it difficult to discern any real or clear trend in truck tonnage."

The not seasonally adjusted index, which represents the change in tonnage actually hauled by the fleets before any seasonal adjustment, equaled 136.4 in September, which was 5.1% below the previous month’s reading of 143.8.

“Adjusting for the larger ups and downs this year, as well as talking with many fleets, I currently see a softer than normal freight environment, which is likely to continue until the inventory correction is complete,” said Costello.

“Looking ahead," he added, "the slow growth economic environment does not suggest that significantly stronger truck tonnage numbers are in the near term either.”