At the conclusion of such hearing, the board shall consider the evidence taken and shall make specific findings with respect to the objections and issues within thirty days after the hearing, which findings shall approve, disapprove, or modify the proposed plan of the department of transportation. Such findings shall be final and binding upon both parties. Any modification of the proposed plan of the department of transportation made by the board of review may thereafter be modified by stipulation of the parties.
RCW 47.52.180