Property, Plant and Equipment
 12 Months Ended
Dec. 31, 2015
Property, Plant and Equipment [Abstract]  
Property, Plant and Equipment
Property, plant and equipment, which are used to secure debt or are subject to lien, at cost, as of December 31, 2015 and 2014 were as follows (in thousands):
 
 
 
December 31,
 
 
2015
 
2014
Construction equipment
 
$
61,924

 
$
86,174

Furniture and equipment
 
31,921

 
38,477

Land and buildings
 
1,725

 
8,664

Transportation equipment
 
75,395

 
98,185

Leasehold improvements
 
6,725

 
9,354

Marine equipment
 
82

 
82

Total property, plant and equipment
 
177,772

 
240,936

Less: accumulated depreciation
 
(127,420
)
 
(155,287
)
Total property, plant and equipment, net
 
$
50,352

 
$
85,649


Amounts above include $1.2 million and $1.9 million of construction in progress as of December 31, 2015 and 2014, respectively. Depreciation expense included in operating expenses for the years ended December 31, 2015, 2014 and 2013 was $17.3 million, $22.0 million and $24.5 million, respectively.
Assets Held for Sale
During the year ended December 31, 2015, the Company recorded impairment charges of approximately $3.3 million related to property, plant and equipment in the Oil & Gas and Utility T&D segments, which were classified as held for sale at December 31, 2015. The held for sale property, plant and equipment in the Oil & Gas segment relates to the segment's fabrication services which was actively marketed for sale at December 31, 2015 and subsequently sold in the first quarter of 2016. The held for sale property, plant and equipment in the Utility T&D segment was also being actively marketed to outside parties and auction groups at December 31, 2015. The total impairment charges, which were recorded to measure the equipment at the lower of its carrying value or fair value less costs to sell, are included in operating expenses in the Company's Consolidated Statement of Operations for the year ended December 31, 2015.