I. There is established the department of transportation, an agency of the state under the executive direction of a commissioner of transportation.
II. The department of transportation, through its officials, shall be responsible for the following general functions:
(a) Planning, developing, and maintaining a state transportation network which will provide for safe and convenient movement of people and goods throughout the state by means of a system of highways, railroads, air service, mass transit, and other practicable modes of transportation, in order to support state growth and economic development and promote the general welfare of the citizens of the state.
(b) Performing any regulation of transportation activities required by law which is not within the jurisdiction of another state agency.