The annualized turnover rate for linehaul truckload fleets of all sizes surged in the second quarter, with turnover at large fleets breaking the 100% barrier for the first time in more than four years, according to American Trucking Associations' quarterly Trucking Activity Report.

For large truckload fleets, those who report in excess of $30 million in revenue, driver turnover rose 16 percentage points to 106% - the highest level since the fourth quarter of 2007. The last time the turnover rate was over 100% was in the first quarter of 2008.

"We continue to see steady, albeit sluggish, growth in freight volumes, which increases demand for drivers," ATA Chief Economist Bob Costello said. "That, coupled with continued pressure on fleets to improve their safety records as a result of regulatory oversight changes, is increasing competition among carriers for drivers with clean histories."

TCA's Safety and Policy Director Dave Heller agrees that the two main reasons behind high driver turnover rates are an economic shift in industries, and an industry-wide higher importance placed on safety.

"Drivers need to go where the need where the freight is," Heller says, "and it is a fact that some industries are in economic upswing and others are in an economic downswing. Another reason is with CSA, safe drivers are much more valuable to carriers, and that enables those drivers to go to better carriers."

At smaller truckload fleets, turnover jumped to 86% in the second quarter, a 15-point jump over the previous quarter. The spike put turnover at its highest level since the third quarter of 2007.

"We have been contending that the driver shortage is by and large qualitative, rather than quantitative," Costello said. "Despite some estimates, I believe that in terms of raw numbers, the trucking industry is currently short somewhere in the range of 20,000 to 30,000 drivers. However, if we continue to see growth in freight volumes, we can expect that number to rise in the near future, exacerbating the qualitative shortage and creating a quantitative one."

The turnover rate for less-than-truckload fleets averaged just 9% in the second quarter, up from 8% in the previous quarter.