The following tables list the major categories of property and equipment, as well as the weighted-average estimated useful life for each category (in years):


Millions, except estimated useful life As of March 31, 2026	Cost		Accumulated depreciation		Net book value		Estimated useful life
Land	$	5,475	N/A		$	5,475	N/A
Road:
Rail and other track material	19,831		8,016		11,815		43
Ties	12,893		4,361		8,532		34
Ballast	6,686		2,345		4,341		34
Other roadway [a]	24,719		6,186		18,533		47
Total road	64,129		20,908		43,221		N/A
Equipment:
Locomotives	10,059		3,801		6,258		17
Freight cars	3,090		1,133		1,957		23
Work equipment and other	1,343		555		788		17
Total equipment	14,492		5,489		9,003		N/A
Technology and other	1,430		688		742		12
Construction in progress	1,514		N/A		1,514		N/A
Total	$	87,040	$	27,085	$	59,955	N/A


Millions, except estimated useful life As of December 31, 2025	Cost		Accumulated depreciation		Net book value		Estimated useful life
Land	$	5,471	N/A		$	5,471	N/A
Road:
Rail and other track material	19,747		7,936		11,811		45
Ties	12,779		4,305		8,474		34
Ballast	6,646		2,309		4,337		34
Other roadway [a]	24,610		6,080		18,530		47
Total road	63,782		20,630		43,152		N/A
Equipment:
Locomotives	9,926		3,813		6,113		18
Freight cars	3,080		1,107		1,973		23
Work equipment and other	1,318		540		778		17
Total equipment	14,324		5,460		8,864		N/A
Technology and other	1,414		669		745		12
Construction in progress	1,413		N/A		1,413		N/A
Total	$	86,404	$	26,759	$	59,645	N/A