Today, the third installment of our look back at the top trucking stories from 2012, as determined by HDT's editors.

The new HOS rule was technically unveiled in the last days of 2011, but in February, the American Trucking Associations sued to overturn it, asking the U.S. Circuit Court of Appeals for the District of Columbia to set aside the Federal Motor Carrier Safety Administration rule as arbitrary and capricious. ATA said the agency overstated the safety benefits of the new rule, and that the costs outweigh the claimed benefits.

ATA and others object to a change in which the 34-hour restart will be limited to once a week, with each restart including two rest periods between 1 a.m. and 5 a.m.

They also object to the requirement that a driver must take a half-hour off if its been more than eight hours since he took an off-duty or sleeper berth break.

They contend that the rules established in 2004 work well and have contributed to significant improvements in industry safety.

The safety advocacy groups weren't happy with it, either, and they too sued, saying the agency abused its discretion when it preserved the restart and the daily limit. They also say the agency erred in its decision not to reduce the 11-hour limit on daily driving.

Oral arguments in the lawsuit challenging the hours of service rule will be held March 15. It typically takes the court two to three months to rule following arguments, which means it should hand down its decision before the new HOS rule is scheduled to take effect in July.

The slowly recovering economy continues to be a top concern on the minds of trucking fleets, although in many cases trucking is doing better than the overall economy.

A year ago, in HDT's December 2011 issue, we reported that the National Association for Business Economics Outlook Survey was predicting 2.4% GDP growth in 2012, slightly stronger in the second half than the first. While final 2012 numbers aren't in yet, Figures released Dec. 20 by the U.S. Department of Commerce show that real gross domestic product -- the output of goods and services produced by labor and property located in the United States -- increased at an annual rate of 3.1% in the third quarter, and in the second quarter, real GDP increased 1.3%. Housing in particular is showing signs of coming back from its deep slump.

Fleets so far have been very cautious in adding any capacity, and the recession drove a fair amount of capacity out of the industry. American Trucking Associations Chief Economist Bob Costello says large truckload fleets are about 5% smaller than before the recession, small truckload carriers about 9%, and less-than-truckload about 11%.

"When the economy takes off, we're certainly going to have to add more trucks," he said during ATA's annual management conference in October. "If the overall economy were to surprise us on the upside -- with, say 3% GDP growth for several straight quarters -- we would not have enough trucks to handle the corresponding increase in freight."

Tomorrow, the fourth and final installment