12. Lease Obligations

From time to time, the Company enters into leasing arrangements for real estate, vehicles and construction equipment. In 2016, the Company entered into master leasing arrangements for vehicles and construction equipment. Some of the leases entered into under these agreements were recorded as capital leases while others were treated as operating leases. As of December 31, 2016, the Company had no outstanding commitments to enter into future leases under its master lease agreements.

Capital Leases

The Company leases vehicles and certain equipment under capital leases. The economic substance of the leases is a financing transaction for acquisition of the vehicles and equipment and, accordingly, the leases are included in the balance sheets in property and equipment, net of accumulated depreciation, with a corresponding amount recorded in current portion of capital lease obligations or capital lease obligations, net of current maturities, as appropriate. The capital lease assets are amortized over the life of the lease or, if shorter, the life of the leased asset, on a straight-line basis and included in depreciation expense in the statements of operations. The interest associated with capital leases is included in interest expense in the statements of operations.

As of December 31, 2016, the Company had approximately $4.9 million of capital lease obligations outstanding, $1.1 million of which was classified as a current liability. As of December 31, 2015, the Company had no outstanding capital lease obligations.

As of December 31, 2016, $5.0 million of leased assets were capitalized in construction equipment, net of accumulated depreciation. Additional information related to property and equipment is provided in Note 6 to the Financial Statements.

Operating Leases

The Company leases real estate, construction equipment and office equipment under operating leases with remaining terms ranging from one to five years.

Rent expense includes lease payments as well as rent on items that are rented under cancellable rental agreements. Total rent expense for the years ended December 31, 2016, 2015 and 2014, was $44.9 million, $57.2 million and $41.1 million, respectively.

The future minimum lease payments required under capital leases and operating leases, together with their present value of capital leases, as of December 31, 2016 were as follows:

(In thousands)	Capital Lease Obligations			Operating Lease Obligations
2017	$	1,220		$	2,519
2018		1,220			2,256
2019		1,220			1,851
2020		1,220			1,206
2021		380			761
Thereafter		—			612
Total minimum lease payments	$	5,260		$	9,205
Interest		(342	)
Net present of minimum lease payments		4,918
Less: Current portion of capital lease obligations		1,085
Long-term capital lease obligations	$	3,833