1. Fixed assets. To all intents and purposes, the sale value of pulling up all the railways the company owns (perhaps less the cost of demolishing all the stations, signals, airports etc.)
This is probably useful for liquidation purposes only.
2. Depreciation. An entry could be made showing the current value of vehicles owned, against their replacement cost (either by new vehicles of the same type, or if obsolete, by their nearest equivalent in terms of capacity, or speed, or horsepower).
This could also be expressed as a fraction. If the ratio is more than 50%, the company is running mainly new stock. Less than 50% might mean thinking about replacement costs early. Less than 25% means the company is probably running a collection of ancient hacks which spend most of their time standing still belching black smoke (and the company is quite likely ready to go bankrupt).
