The authority for this chapter is RCW 46.61.380 which authorizes the superintendent of public instruction to adopt and enforce regulations to cover the operation of all school buses transporting common school students. The purpose of this chapter is to establish the manner of operating all school buses owned and operated by any school district and all school buses which are privately owned and operated under contract or otherwise with any school district in the state for the transportation of students. This chapter does not apply to the operation of buses by common carrier in the urban transportation of students (e.g., the transportation of students via a municipal transit system).