Wash. Rev. Code § 35.71.030
When the corporate authority determines that the public interest, safety, and convenience is best served by the establishment of a mall and that vehicular traffic will not be unduly inconvenienced thereby, it may adopt a resolution declaring its intention to do so, and announcing the intended extent of traffic limitation. Any corporate authority is authorized to limit the utilization of any right-of-way, except for utilities and governmental functions, provided adequate alternative routes for vehicular movement, and the loading and unloading of goods are established or are available. The abutting property owner's right of ingress and egress shall be considered to have been satisfied whenever the corporate authority has planned and constructed, or there is available, an alternate route, alleyway, and service driveway.
RCW 35.71.030