The following table shows the components of our operating assets and facilities as of December 31 (in millions):
| | | | | | | | | | | |
| 2025 | | 2024 |
| Railcars and locomotives | $ | 13,802.1 | | | $ | 12,702.9 | |
| Aircraft spare engines | 1,177.5 | | | 1,030.4 | |
| Tank containers | 278.0 | | | 241.4 | |
| Buildings, leasehold improvements, and other equipment | 318.5 | | | 265.3 | |
| Other | 86.5 | | | 90.6 | |
| $ | 15,662.6 | | | $ | 14,330.6 | |
| Less: allowance for depreciation | (4,251.7) | | | (3,880.9) | |
| Net operating assets and facilities | $ | 11,410.9 | | | $ | 10,449.7 | |
The following table shows the components of our total depreciation expense for the years ended December 31 (in millions):
| | | | | | | | | | | | | | | | | |
| 2025 | | 2024 | | 2023 |
| Operating assets and facilities, included in depreciation expense | $ | 431.8 | | | $ | 402.4 | | | $ | 376.3 | |
| Maintenance operating assets and facilities, included in maintenance expense | 13.4 | | | 11.8 | | | 9.3 | |
| Depreciation on operating assets and facilities | $ | 445.2 | | | $ | 414.2 | | | $ | 385.6 | |
| Non-operating assets, included in SG&A | 6.5 | | | 6.7 | | | 5.9 | |
| Total depreciation expense | $ | 451.7 | | | $ | 420.9 | | | $ | 391.5 | |
About PP&E Disclosures
The PP&E disclosure details a company's physical asset base — land, buildings, machinery, and equipment — along with the depreciation methods and useful life assumptions that determine how these costs flow through the income statement. Capitalization policy thresholds reveal management's judgment on the boundary between expense and asset, directly affecting both reported earnings and asset values.
Key signals: changes in estimated useful lives or depreciation methods can materially shift reported earnings without any operational change. Compare capital expenditures against depreciation expense — when capex consistently trails depreciation, the asset base may be aging and underinvested. Watch for large asset impairments or write-downs that signal overvalued carrying amounts. Asset retirement obligations reveal future environmental or decommissioning costs that are often underappreciated. Compare PP&E intensity (PP&E-to-revenue) against industry peers to assess capital efficiency and competitive positioning.