The commission may, upon complaint or upon its own motion, prescribe and authorize just and reasonable rates for the transportation of persons or property for any public service company subject to regulation by the commission as to rates and service, whenever and as often as it deems necessary or proper. The commission shall, before any hearing upon the complaint or motion, notify the complainants and the carrier concerned of the time and place of the hearing by giving at least ten days' written notice thereof, specifying that at the time and place designated a hearing will be held for the purpose of prescribing and authorizing the rates. The notice is sufficient to authorize the commission to inquire into and pass upon the matters designated in this section.
In exercising this power, the commission may use any standard, formula, method, or theory of valuation reasonably calculated to arrive at the objective of prescribing and authorizing just and reasonable rates.
In the exercise of this power, the commission may consider, in addition to other factors, the following:
RCW 81.04.250