7. Property and equipment

The following is a summary of property and equipment, at cost less accumulated depreciation and amortization:


	December 31,
	2018		2017
Leasehold improvements	$	474,808	$	418,023
Software		51,534		42,281
Construction in progress		40,369		27,291
Computer equipment		14,215		13,245
Furniture, fixtures and office equipment		2,141		1,806
Total property and equipment		583,067		502,646
Less: accumulated depreciation and amortization		(268,888)		(240,287)
Total property and equipment, net	$	314,179	$	262,359

Included in property and equipment at December 31, 2018 and 2017 was equipment acquired under capital leases totaling $16,284 and $12,714, respectively, and related accumulated depreciation and amortization of $6,245 and $3,744, respectively.

Depreciation and amortization expense, which includes depreciation and amortization for property and equipment under capital leases, is allocated on a specific identification basis as follows on the accompanying consolidated statements of operations:


	Year Ended
	December 31,
	2018		2017		2016
Network access	$	49,766	$	42,435	$	27,013
Network operations		17,590		16,382		13,966
Development and technology		10,443		9,247		7,207
General and administrative		1,038		1,033		1,016
Total depreciation and amortization of property and equipment	$	78,837	$	69,097	$	49,202

During the years ended December 31, 2018, 2017, and 2016 we recognized $148, $882, and $54, respectively, of impairment losses primarily related to construction in progress projects that were abandoned. During the years ended December 31, 2018 and 2017, we also recognized $90 and $276, respectively, of losses on disposals of property and equipment.