This chapter is enacted for the purpose of promoting health, safety, morals and the general welfare of the community, in accordance with a comprehensive plan designed to lessen congestion in the streets; to secure safety from fire, panic and other dangers; to promote health and the general welfare; to provide adequate light and air; to prevent the overcrowding of land; to avoid undue concentration of population; and to facilitate the adequate provision of transportation, water, sewage, schools, parks and other public requirements.