The American Trucking Associations' advance seasonally adjusted (SA) For-Hire Truck Tonnage Index increased 1.6% in September after falling a revised 0.5% in August 2011. August's decrease was more than the 0.2% drop ATA reported on September 27, 2011. The latest gain put the SA index at 115.8 (2000=100) in September, up from the August level of 114.

The not seasonally adjusted index, which represents the change in tonnage actually hauled by the fleets before any seasonal adjustment, equaled 119.5 in September, which was 3.1% below the previous month.

Compared with September 2010, SA tonnage was up a solid 5.9%. In August, the tonnage index was 4.9% above a year earlier.

'I continue to believe the economy will skirt another recession because truck tonnage isn't showing signs that we are in a recession,' ATA Chief Economist Bob Costello said. 'Tonnage is suggesting that we are in a weak growth period for the economy, but not a recession.'

Costello also noted that the third quarter average exhibited signs of small gains for the broader economy, not contraction. 'In the third quarter, tonnage was up 0.4% from the second quarter. Prior to the two previous recessions truck tonnage was plummeting, but not this time.'

Note on the impact of trucking company failures on the index: Each month, ATA asks its membership the amount of tonnage each carrier hauled, including all types of freight. The indexes are calculated based on those responses. The sample includes an array of trucking companies, ranging from small fleets to multi-billion dollar carriers. When a company in the sample fails, we include its final month of operation and zero it out for the following month, with the assumption that the remaining carriers pick up that freight. As a result, it is close to a net wash and does not end up in a false increase. Nevertheless, some carriers are picking up freight from failures and it may have boosted the index. Due to our correction mentioned above however, it should be limited.

Trucking serves as a barometer of the U.S. economy, representing 67.2% of tonnage carried by all modes of domestic freight transportation, including manufactured and retail goods. Trucks hauled 9 billion tons of freight in 2010. Motor carriers collected $563.4 billion, or 81.2% of total revenue earned by all transport modes.

ATA calculates the tonnage index based on surveys from its membership and has been doing so since the 1970s. This is a preliminary figure and subject to change in the final report issued around the 10th day of the month. The report includes month-to-month and year-over-year results, relevant economic comparisons, and key financial indicators.