For the purposes of this chapter the following definitions shall apply:

(1) “Authority” means the county transportation authority created pursuant to this chapter.

(2) “Population” means the number of residents as shown by the figures released for the most recent official state, federal, or county census, or population determination made by the office of financial management.

(3) “Public transportation function” means the transportation of passengers and their incidental baggage by means other than by chartered bus, sightseeing bus, together with the necessary passenger terminals and parking facilities or other properties necessary for passenger and vehicular access to and from such people-moving systems, and may include contracting for the provision of ambulance services for the transportation of the sick and injured: PROVIDED, That such contracting for ambulance services shall not include the exercise of eminent domain powers: PROVIDED, FURTHER, That nothing shall prohibit an authority from leasing its buses to private certified carriers or prohibit the county from providing school bus service.

Population determinations, office of financial management: Chapter 43.62 RCW.