(2) Whenever a power is granted to the commission the power may be exercised by such officer or employee within the Department of Transportation as is designated in writing by the commission. Any such designation shall be filed in the office of the Secretary of State. The authority to delegate granted by this subsection includes, but is not limited to, authority to delegate the power to adopt rules for the department. [1969 c.599 §6; 1973 c.249 §14; 1993 c.741 §9]