The 2013 income statement and balance sheet (excerpts) for BNSF Railway are below.

Burlington Northern Santa Fe, LLC and Subsidiaries
Consolidated Statements of Income
Year ended December 31,	2013	2012	2011
(In millions)
Revenues	22,014	$20,835	$19,548
Operating expenses:
Compensation and benefits	4,651	4,505	4,315
Fuel	4,503	4,459	4,267
Purchased services	2,418	2,374	2,218
Depreciation and amortization	1,973	1,889	1,807
Equipment rents	822	810	779
Materials and other	980	786	852
Total operating expenses	15,347	14,823	14,238
Operating income	6,667	6,012	5,310
Interest expense	729	623	560
Other expense, net	10	12	9
Income before income taxes	5,928	5,377	4,741
Income tax expense	2,135	2,005	1,769
Net income	$ 3,793	$ 3,372	$ 2,972

Burlington Northern Santa Fe, LLC and Subsidiaries
Consolidated Balance Sheets (excerpts)
Dollars in millions
December 31,	2013	2012
Cash and cash equivalents	$ 2,225	$ 1,794
Accounts receivable, net of allowance of $39 and $27	1,298	1,168
Materials and supplies	835	800
Current portion of deferred income taxes	358	341
Other current assets	87	78
Total current assets	4,803	4,181
Property and equipment, net	52,363	50,070
Goodwill	14,819	14,819
Intangible assets, net	821	1,128
Other assets	2,224	1,816
Total assets	$75,030	$72,014

The footnotes to the financial statements included the following:

Property and equipment, net (in millions) is as follows:

December 31,	2013	2012
Land	$ 5,973	$ 5,950
Track structure	18,207	17,319
Other roadway	21,891	20,936
Locomotives	5,241	4,505
Freight cars and other equipment	2,053	1,744
Computer hardware and software	257	279
Construction in progress	973	963
Total cost	54,595	51,696
Less accumulated depreciation and amortization	(2,232)	(1,626)
Property and equipment, net	$52,363	$50,070

Required:

What proportion of total assets, does BNSF hold as property and equipment in 2013 and 2012? Does this surprise you?

What economic assets might not be reflected on the BNSF balance sheet?

Compute property and equipment turnover for 2013 and 2012. Property and equipment, net for 2011 was $48,047 million. Explain this ratio.

By what percentage are the assets used up at the year-end 2013? What implication does this ratio have for future cash flows at BNSF?

Estimate the useful life on average for the BNSF depreciable assets. Which of the assets listed in the footnote explain this estimated useful life?