Each local board of education shall adopt and enforce rules and regulations whereby a parent or guardian may elect to waive bus transportation for that parent's or guardian's student to and from school in favor of another form of transportation. The principal of each school may issue passes for school bus transportation to certain pupils who have chosen to drive a private vehicle, for use on a temporary and emergency basis; and may also set aside a specific number of parking spaces for use on a temporary and emergency basis by pupils who originally chose transportation by school bus. Any contract between the Department of Education and a supplier of bus transportation, or between a local school board and a supplier of bus transportation, shall be based upon the number of students who elect to be transported by bus, and shall not be based upon the total number of students in the school or school district.