Wash. Rev. Code § 81.80.190
The commission shall, in issuing permits to common carriers and contract carriers under this chapter, require the carriers to either procure and file liability and property damage insurance from a company licensed to write such insurance in the state of Washington, or deposit security, for the limits of liability and on terms and conditions that the commission determines are necessary for the reasonable protection of the public against damage and injury for which the carrier may be liable by reason of the operation of any motor vehicle.
In fixing the amount of the insurance policy or policies, or deposit of security, the commission shall consider the character and amount of traffic and the number of persons affected and the degree of danger that the proposed operation involves.
RCW 81.80.190
Construction-1986 c 191: See RCW 70A.384.902.