(a) Hearing
The Commission may from time to time, as may be necessary for the proper administration of this chapter, and after opportunity for hearing, make a valuation of all or of any part of the property owned or used by any carrier subject to this chapter, as of such date as the Commission may fix.

(b) Inventory
The Commission may at any time require any such carrier to file with the Commission an inventory of all or of any part of the property owned or used by said carrier, which inventory shall show the units of said property classified in such detail, and in such manner, as the Commission shall direct, and shall show the estimated cost of reproduction new of said units, and their reproduction cost new less depreciation, as of such date as the Commission may direct; and such carrier shall file such inventory within such reasonable time as the Commission by order shall require.

(c) Original cost
The Commission may at any time require any such carrier to file with the Commission a statement showing the original cost at the time of dedication to the public use of all or of any part of the property owned or used by said carrier. For the showing of such original cost said property shall be classified, and the original cost shall be defined, in such manner as the Commission may prescribe; and if any part of such cost cannot be determined from accounting or other records, the portion of the property for which such cost cannot be determined shall be reported to the Commission; and, if the Commission shall so direct, the original cost thereof shall be estimated in such manner as the Commission may prescribe. If the carrier owning the property at the time such original cost is reported shall have paid more or less than the original cost to acquire the same, the amount of such cost of acquisition, and any facts which the Commission may require in connection therewith, shall be reported with such original cost. The report made by a carrier under this subsection shall show the source or sources from which the original cost reported was obtained, and such other information as to the manner in which the report was prepared, as the Commission shall require.

(d) Easement, license or franchise
Nothing shall be included in the original cost reported for the property of any carrier under subsection (c) of this section on account of any easement, license, or franchise granted by the United States or by any State or political subdivision thereof, beyond the reasonable necessary expense lawfully incurred in obtaining such easement, license, or franchise from the public authority aforesaid, which expense shall be reported separately from all other costs in such detail as the Commission may require; and nothing shall be included in any valuation of the property of any carrier made by the Commission on account of any such easement, license, or franchise, beyond such reasonable necessary expense lawfully incurred as aforesaid.

(e) Improvements; changes in condition
The Commission shall keep itself informed of all new construction, extensions, improvements, retirements, or other changes in the condition, quantity, use, and classification of the property of common carriers, and of the cost of all additions and betterments thereto and of all changes in the investment therein, and may keep itself informed of current changes in costs and values of carrier properties.

(f) Additional information; access to records and data
For the purpose of enabling the Commission to make a valuation of any of the property of any such carrier, or to find the original cost of such property, or to find any other facts concerning the same which are required for use by the Commission, it shall be the duty of each such carrier to furnish to the Commission, within such reasonable time as the Commission may order, any information with respect thereto which the Commission may by order require, including copies of maps, contracts, reports of engineers, and other data, records, and papers, and to grant to all agents of the Commission free access to its property and its accounts, records, and memoranda whenever and wherever requested by any such duly authorized agent, and to cooperate with and aid the Commission in the work of making any such valuation or finding in such manner and to such extent as the Commission may require and direct, and all rules and regulations made by the Commission for the purpose of administering this section shall have the full force and effect of law. Unless otherwise ordered by the Commission, with the reasons therefor, the records and data of the Commission shall be open to the inspection and examination of the public. The Commission, in making any such valuation, shall be free to adopt any method of valuation which shall be lawful.

(g) State commissions
Nothing in this section shall impair or diminish the powers of any State commission.