Thinking about the issue of recapitulation of the rolling stock and locomotive fleets of larger railroads . . .
I think it safe to say that (1) virtually all the major railroads had diagram books of both freight and passenger equipment and (2) all of the rolling stock was carefully accounted for, as to numbers of cars in a particular class and so on, and that (3) a reasonably close approximation of the total value for accounting purposes could be established by using the descriptions in the diagram books and the quantity of cars in each class.
This does rather fly in the face of the extraordinary detail discussed by me and others WRT fixed structures and rights of way, but OTOH, given that rolling stock doesn’t stand still to be evaluated and inventoried, it seems (to me) likely that this mathematical approach to establishing the total value of a road’s rolling stock may have been acceptable to the Federal Government.
The same approach could be used to establish the value of a fleet of locomotives.
I’m thinking that this approach would apply to many Class 1 railroads. Small lines may well have been able to actually inventory their fleets of cars and engines.