Authorizes public transportation service providers, including private, nonprofit transportation providers regulated under chapter 81.66 RCW, to allow the driver of a transit vehicle to stop upon the roadway momentarily to receive or discharge passengers at an unmarked stop zone if the driver stops the vehicle as far to the right side of the roadway as possible to not significantly impede traffic, the driver activates four-way flashing lights, and the driver stops at a portion of the highway with an unobstructed view so as to not create a hazard.