This chapter providing for parking and business improvement areas shall not be deemed or construed to affect any existing act, or any part thereof, relating to special assessments or other powers of counties, cities and towns, but shall be supplemental thereto and concurrent therewith.

The purposes and functions of parking and business improvement areas as set forth by the provisions of this chapter may be accomplished in part by the establishment of an area pursuant to this chapter and in part by any other method otherwise provided by law, including provisions for local improvements.