Summary of Significant Accounting Policies

Description of Business

Norfolk Southern Corporation (Norfolk Southern) is a Virginia-based holding company engaged principally in the rail transportation business, operating approximately 20,000 miles of road primarily in the East and Midwest. These consolidated financial statements include Norfolk Southern and its majority-owned and controlled subsidiaries (collectively, NS, we, us, and our). Norfolk Southern’s major subsidiary is Norfolk Southern Railway Company (NSR). All significant intercompany balances and transactions have been eliminated in consolidation.

NSR and its railroad subsidiaries transport raw materials, intermediate products, and finished goods classified in the following commodity groups (percent of total railway operating revenues in 2015): intermodal (23%); coal (17%); chemicals (17%); agriculture/consumer products/government (15%); metals/construction (12%); automotive (9%); and, paper/clay/forest products (7%). Although most of our customers are domestic, ultimate points of origination or destination for some of the products transported (particularly coal bound for export and some intermodal containers) may be outside the U.S. More than 80% of our railroad employees are covered by collective bargaining agreements with various labor unions.

Use of Estimates

The preparation of financial statements in accordance with U.S. Generally Accepted Accounting Principles (GAAP) requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. We periodically review our estimates, including those related to the recoverability and useful lives of assets, as well as liabilities for litigation, environmental remediation, casualty claims, income taxes and pension and other postretirement benefits. Changes in facts and circumstances may result in revised estimates.

Revenue Recognition

Transportation revenue is recognized proportionally as a shipment moves from origin to destination, and related expenses are recognized as incurred. Refunds (which are primarily volume-based incentives) are recorded as a reduction to revenues on the basis of management’s best estimate of projected liability, which is based on historical activity, current shipment counts and the expectation of future activity. We regularly monitor our contract refund liability and, historically, the estimates have not differed significantly from the amounts ultimately refunded. Switching, demurrage and other incidental service revenues are recognized when the services are performed.

Cash Equivalents

“Cash equivalents” are highly liquid investments purchased three months or less from maturity.

Allowance for Doubtful Accounts

Our allowance for doubtful accounts was $3 million at December 31, 2015 and $6 million at December 31, 2014. To determine our allowance for doubtful accounts, we evaluate historical loss experience (which has not been significant), the characteristics of current accounts, and general economic conditions and trends.

Materials and Supplies

“Materials and supplies,” consisting mainly of fuel oil and items for maintenance of property and equipment, are stated at the lower of average cost or market. The cost of materials and supplies expected to be used in property additions or improvements is included in “Properties.”

Investments

Investments where we have the ability to exercise significant influence over but do not control the entity are accounted for using the equity method, whereby the investment is carried at the cost of the acquisition plus our equity in undistributed earnings or losses since acquisition.

Properties

“Properties” are stated principally at cost and are depreciated using the group method whereby assets with similar characteristics, use, and expected lives are grouped together in asset classes and depreciated using a composite depreciation rate. This methodology treats each asset class as a pool of resources, not as singular items. We use approximately 70 depreciable asset classes. The primary depreciation method for our asset base is group life. Units of production is the principal method of depreciation for rail in high density corridors and for depletion of natural resources (Note 2). Remaining properties are depreciated generally using the straight-line method over the lesser of estimated service or lease lives. Depreciation in the Consolidated Statements of Cash Flows includes both depreciation and depletion.

Depreciation expense is based on our assumptions concerning expected service lives of our properties as well as the expected net salvage that will be received upon their retirement. In developing these assumptions, we utilize periodic depreciation studies that are performed by an independent outside firm of consulting engineers and approved by the Surface Transportation Board (STB). Our depreciation studies are conducted about every three years for equipment and every six years for track assets and other roadway property. The frequency of these studies is consistent with guidelines established by the STB. Key factors that are considered in developing average service life and salvage estimates include:


•	statistical analysis of historical retirement data and surviving asset records;


•	review of historical salvage received and current market rates;


•	review of our operations including expected changes in technology, customer demand, maintenance practices and asset management strategies;


•	review of accounting policies and assumptions; and


•	industry review and analysis.

The units of production depreciation rate for rail in high density corridors is derived based on consideration of annual gross ton miles as compared to the total or ultimate capacity of rail in these corridors. Our experience has shown that traffic density is a leading factor in determination of the expected service life of rail in high density corridors. In developing the respective depreciation rate, consideration is also given to several rail characteristics including age, weight, condition (new or second hand) and type (curve or straight). As a result, a composite depreciation rate is developed which is applied to the depreciable base.

We adjust our rates based on the results of these studies and implement the changes prospectively. The studies may also indicate that the recorded amount of accumulated depreciation is deficient (or in excess) of the amount indicated by the study. Any such deficiency (or excess) is amortized as a component of depreciation expense over the remaining service lives of the affected class of property, as determined by the study. For 2015, roadway depreciation rates ranged from 0.83% to 33.33% and equipment depreciation rates ranged from 1.55% to 33.33%.

We capitalize interest on major projects during the period of their construction. Expenditures, including those on leased assets, that extend an asset’s useful life or increase its utility are capitalized. Expenditures capitalized include those that are directly related to a capital project and may include materials, labor and equipment, in addition to an allocable portion of indirect costs that clearly relate to a particular project. Due to the capital intensive nature of the railroad industry, a significant portion of annual capital spending relates to the replacement of self-constructed assets. Because removal activities occur in conjunction with replacement, removal costs are estimated based on an average percentage of time employees replacing assets spend on removal functions. Costs related to repairs and maintenance activities that do not extend an asset’s useful life or increase its utility are expensed when such repairs are performed.

When properties other than land and nonrail assets are sold or retired in the ordinary course of business, the cost of the assets, net of sale proceeds or salvage, is charged to accumulated depreciation, and no gain or loss is recognized in earnings. Actual historical cost values are retired when available, such as with equipment assets. The use of estimates in recording the retirement of certain roadway assets is necessary based on the impracticality of tracking individual asset costs. When retiring rail, ties and ballast, we use statistical curves that indicate the relative distribution of the age of the assets retired. The historical cost of other roadway assets is estimated using a combination of inflation indices specific to the rail industry and those published by the U.S. Bureau of Labor Statistics. The indices are applied to the replacement value based on the age of the retired assets. These indices are used because they closely correlate with the costs of roadway assets. Gains and losses on disposal of land and nonrail assets are included in “Other income – net” (Note 2) since such income is not a product of our railroad operations.

A retirement is considered abnormal if it does not occur in the normal course of business, if it relates to disposition of a large segment of an asset class and if the retirement varies significantly from the retirement profile identified through our depreciation studies, which inherently consider the impact of normal retirements on expected service lives and depreciation rates. Gains or losses from abnormal retirements are recognized in earnings.

We review the carrying amount of properties whenever events or changes in circumstances indicate that such carrying amount may not be recoverable based on future undiscounted cash flows. Assets that are deemed impaired as a result of such review are recorded at the lower of carrying amount or fair value.

Required Accounting Changes

In April 2015, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2015-03, “Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs.” This update requires that debt issuance costs be presented in the balance sheet as a reduction from the related debt liability rather than as an asset, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs are not affected by the amendments in this update. We early adopted the provisions of this ASU during the second quarter of 2015 and applied it retrospectively. The adoption of ASU 2015-03 resulted in the presentation of $47 million of debt issuance costs as a reduction of “Long-term debt” at December 31, 2015. We retrospectively adjusted the December 31, 2014, 2013, 2012, and 2011 consolidated balance sheets and related disclosures to reflect the reclassification of $41 million, $44 million, $40 million, and $33 million of debt issuance costs, respectively, from “Other assets” to “Long-term debt.” There was no other impact on our consolidated financial statements from the adoption of ASU 2015-03.

In May 2014, the FASB issued ASU No. 2014-09, "Revenue from Contracts with Customers." This update will replace most existing revenue recognitionguidance in GAAP and requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. In July 2015, the FASB approved a one-year deferral of the effective date of the new standard, making it effective for our annual and interim reporting periods beginning January 1, 2018. Early application is permitted, but not before the original effective date for public business entities (annual reporting periods beginning after December 15, 2016). The ASU permits the use of either the retrospective or cumulative effect transition method. We are evaluating the effect that ASU 2014-09 will have on our consolidated financial statements and related disclosures.

In November 2015, the FASB issued ASU No. 2015-17, “Income Taxes (Subtopic 740): Balance Sheet

Classification of Deferred Taxes.” This update, effective for annual and interim periods beginning after December 15, 2016, requires that deferred tax liabilities and assets be classified as noncurrent on the balance sheet rather than as separate current and noncurrent amounts on the balance sheet. Early application is permitted as of the beginning of an interim or annual reporting period, and may be applied either prospectively or retrospectively. This update, once adopted, will not have a material effect on our presentation of deferred tax liabilities and assets on our balance sheet.