property, plant and equipment

6 Months Ended

Jun. 30, 2018

property, plant and equipment

property, plant and equipment

17property, plant and equipment

(millions)	Note	Network assets			Buildings and leasehold improvements			Other		Land		Assets under construction			Total
At cost
As at January 1, 2018		$	28,724		$	3,077		$	1,095	$	48	$	655		$	33,599
Additions		492			13			16		—		639			1,160
Additions arising from business acquisitions	18(b)	—			1			6		—		—			7
Dispositions, retirements and other		(454		)	(9		)	11		—		—			(452		)
Assets under construction put into service		496			46			31		—		(573		)	—
As at June 30, 2018		$	29,258		$	3,128		$	1,159	$	48	$	721		$	34,314
Accumulated depreciation
As at January 1, 2018		$	19,638		$	1,884		$	709	$	—	$	—		$	22,231
Depreciation		709			56			57		—		—			822
Dispositions, retirements and other		(455		)	(14		)	18		—		—			(451		)
As at June 30, 2018		$	19,892		$	1,926		$	784	$	—	$	—		$	22,602
Net book value
As at December 31, 2017		$	9,086		$	1,193		$	386	$	48	$	655		$	11,368
As at June 30, 2018		$	9,366		$	1,202		$	375	$	48	$	721		$	11,712

As at June 30, 2018, our contractual commitments for the acquisition of property, plant and equipment totalled $177 million over a period ending December 31, 2022 (December 31, 2017 — $184 million over a period ending December 31, 2020).