Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2014

Property, Plant and Equipment

Schedule of property, plant and equipment at cost net of accumulated depreciation

December 31,	2014			2013
(in thousands)
Land	$	18,563		$	19,264
Buildings and leasehold improvements		134,994			130,072
Operating equipment		1,425,846			1,231,504
Computer software		19,005			17,121
Furniture and fixtures		7,835			7,737
Vehicles		479,628			387,854
Construction in progress		2,675			2,076
Gross property, plant and equipment		2,088,546			1,795,628
Less: accumulated depreciation		(1,239,163	)		(1,069,321	)
Net property, plant and equipment	$	849,383		$	726,307