This paper deals planning processes for improvements of residential traffics from the point of view that planning processes must be adapted to a planning environments. The situation and characteristics of Contingency Planning is clarified through the historical review of planning theories. We intend to adapt it to residential traffic planning. Namely through investigations on Roads Improvement Program in Residential Area, relations between planning style and planning environment are discussed to clarify planning processes adapted to situations of each area where the program is introduced. From the result we propose some directions about planning methods for the program.