The components of net properties, plants and equipment were as follows:
 
December 31,
 20252024
 (Dollars in millions)
Coke and energy plant, machinery and equipment$2,047.2 $2,251.0 
Industrial services plant, machinery and equipment419.8 185.4 
Land and land improvements116.7 112.6 
Construction-in-progress64.4 42.9 
Other52.0 49.3 
Gross investment, at cost2,700.1 2,641.2 
Less: accumulated depreciation(1,497.4)(1,497.6)
Total properties, plants and equipment, net$1,202.7 $1,143.6 

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.