Properties (Tables)

3 Months Ended

Mar. 31, 2015

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			Accumulated		Net Book		Estimated
As of March 31, 2015	Cost		Depreciation		Value		Useful Life
Land	$	5,215	$	N/A	$	5,215	N/A
Road:
Rail and other track material		14,745		5,307		9,438	37
Ties		9,194		2,495		6,699	33
Ballast		4,869		1,288		3,581	34
Other roadway [a]		16,615		2,898		13,717	47
Total road		45,423		11,988		33,435	N/A
Equipment:
Locomotives		8,587		3,775		4,812	20
Freight cars		2,106		968		1,138	25
Work equipment and other		742		161		581	18
Total equipment		11,435		4,904		6,531	N/A
Technology and other		899		326		573	11
Construction in progress		1,174		-		1,174	N/A
Total	$	64,146	$	17,218	$	46,928	N/A



Millions, Except Estimated Useful Life			Accumulated		Net Book		Estimated
As of December 31, 2014	Cost		Depreciation		Value		Useful Life
Land	$	5,194	$	N/A	$	5,194	N/A
Road:
Rail and other track material		14,588		5,241		9,347	33
Ties		9,102		2,450		6,652	33
Ballast		4,826		1,264		3,562	34
Other roadway [a]		16,476		2,852		13,624	47
Total road		44,992		11,807		33,185	N/A
Equipment:
Locomotives		8,276		3,694		4,582	20
Freight cars		2,116		968		1,148	25
Work equipment and other		684		153		531	18
Total equipment		11,076		4,815		6,261	N/A
Technology and other		872		320		552	10
Construction in progress		1,080		-		1,080	N/A
Total	$	63,214	$	16,942	$	46,272	N/A

[a]Other roadway includes grading, bridges and tunnels, signals, buildings, and other road assets.