Public Policy necessities for administration of complex and different cities (Case study: Tehran)

Due to complexity and huge varieties in mega cities, their administration need suitable policy making that is designed specifically for each city. So, in the light of contingency approach and collage metaphor, in each city, designing of a mixed policy making system is necessary; a system that is able to use collection of current policy making models, and support urban management system for adopting better decisions. There for it's characteristic and necessities should be designed to be able to answer the continuous changes in complex and variety of cities problem in the future.