The amount of freight carried by the for-hire transportation industry fell 3.6% in January from December, declining after five consecutive monthly increases, according to the DOT's Freight Transportation Services Index.

The Freight TSI, released by the U.S. DOT's Bureau of Transportation Statistics, measures the month-to-month changes in freight shipments in ton-miles, which are then combined into one index. The index measures the output of the for-hire freight transportation industry and consists of data from for-hire trucking, rail, inland waterways, pipelines and air freight.

The level of freight shipments measured by the Freight TSI, 109.7, declined from the all-time high of 113.7 set one month earlier in December.

The results aren't surprising, after the American Trucking Associations reported that its For-Hire Truck Tonnage index also fell in January, by 4% after surging 6.4% in December 2011.

Trend: The DOT says shipments in January 2012 (109.7) were at the second highest level since July 2008 despite the 3.6% decline from December 2011, which was the highest level in the 22-year history of the series. After dipping to a recent low in April 2009 (94.3), freight shipments increased in 23 of the past 33 months, increasing 16.3% during that period.

Index highs and lows: Freight shipments in January 2012 (109.7 on the index) rose 16.3% from the recent low in April 2009 (94.3). In April 2009, freight shipments were at their lowest level since June 1997 (92.3).

Long-term trend: Freight shipments are up 1.2% in the five years from January 2007 and up 11.1% in the 10 years from January 2002 despite declines in recent years.