LEASES

We have operating lease commitments for office and terminal properties, revenue equipment, and computer and office equipment

, and we have capital lease commitments for revenue equipment, in each case excluding owner/operator rentals and month-to-month equipment rentals, summarized for the following fiscal years (in thousands):

	Operating		Capital
2016	$	8,430	$	4,485
2017		5,489		1,656
2018		2,887		1,656
2019		995		1,656
2020		66		3,878
Thereafter		-		2,896
Total minimum lease payments	$	17,867	$	16,227
Less: amount representing interest				(1,649	)
Present value of minimum lease payments				14,578
Less: current portion				(4,031	)
Capital lease obligations, long-term			$	10,547

A portion of our operating leases of tractors and trailers contain residual value guarantees under which we guarantee a certain minimum cash value payment to the leasing company at the expiration of the lease. We estimate that the undiscounted value of the residual guarantees is approximately $4.0 million at December 31, 2015 and 2014, respectively. The residual guarantees at December 31, 2015 expire between August 2018 and February 2019. We expect our residual guarantees to approximate the market value at the end of the lease term. Additionally, certain leases contain cross-default provisions with other financing agreements and additional charges if the unit's mileage exceeds certain thresholds defined in the lease agreement.

Rental expense is summarized as follows for each of the three years ended December 31:

(in thousands)	2015		2014		2013
Revenue equipment rentals	$	12,611	$	20,935	$	22,991
Building and lot rentals		2,078		3,561		4,044
Other equipment rentals		340		317		362
	$	15,029	$	24,813	$	27,397