The trucking company Knight Transportation has revised downward its financial expectations for the third and fourth quarters of 2013.

Based on preliminary results, Knight now expects earnings per diluted share will range from:

• $0.18 to $0.20 for its third quarter ended September 30, compared with its prior estimates of $0.22 to $0.24.

• $0.20 to $0.23 for its fourth quarter ending December 31, compared with its prior estimates of $0.22 to $0.25.

A number of factors negatively impacted the third quarter of 2013, it said in a release, which has resulted in expected earnings below original estimates. “We experienced lower miles per tractor year over year, despite having 3.6% less trucks in the third quarter of 2013 than in the third quarter of 2012, revenue per mile improvement fell short of our targeted level, and increased driver recruiting, training, and payroll costs,”

Soft freight demand, particularly in the first half of the quarter, challenges related to recruiting qualified driving associates, and the new industry-wide regulations governing hours of service that went into effect in July 2013 were among the factors affecting the quarter, said Knight

''In recent weeks, we have seen improvement in driver recruiting, which reduced the number of unseated tractors, and have begun to see pickup in some previously soft freight markets,” said Kevin Knight, chairman and CEO. “We believe that our industry-leading operating efficiency positions Knight for continued success, and enables us to capitalize on growth opportunities during these challenging times in our industry.''

Knight did not provide any update about its pursuit of Arkansas-based trucking company USA Truck, which has been rebuffed by the company.