According to the development of computer abilities, the simulation techniques are widely used in automobile areas instead of actual experiments. In this paper we describe the overview of various simulation techniques those are related to traffic flow, body structure, human model, casualty estimation, and others. Next we introduce the "ASSESS - A Survey Simulator to Evaluate Safety Systems -", which we are developing to analyze effectiveness of active safety systems. The simulator includes driver model, vehicle model to simulate real traffic accidents or near-miss incidents at an intersection. The characteristics and perspective of the simulator are discussed.