Research On Financing Risk Of Rail Transit PPP Project Based On System Dynamics

Since 2014,China has been actively promoting PPP(public private partnership)mode,which has become the most commonly used operation mode in rail transit construction.The introduction of social capital can reduce the financial pressure of the government,speed up the project construction and improve the operation and management level.However,rail transit projects under PPP mode have the characteristics of large financing scale,long life cycle,many stakeholders and low return on investment,which lead to greater risks in the process of project operation.Moreover,the financing risk of rail transit PPP project runs through the whole life cycle of the project,which has the characteristics of complexity,systematicness and dynamic,which brings great difficulties and challenges to the financing risk management.Therefore,it is of great significance to build a more perfect financing risk identification,analysis and evaluation system for rail transit PPP project and to formulate effective risk prevention and control strategies.Firstly,from the perspective of joint social capital led by state-owned enterprises,through case analysis and literature analysis,this paper preliminarily identifies seven target risks and 34 risk factors,including social risk,policy risk,credit risk,credit risk,construction risk,operational risk and financial risk.The causal relationship and feedback mechanism between risks are analyzed by using the system dynamics method,and the causal circuit diagram is drawn.Then,according to the risk structure of causality loop diagram,the corresponding risk variables,influence parameters and function equations are set,and the stock flow diagram of financing risk is drawn.AHP risk matrix and MATLAB software are used to weight the risk factors,and a complete financing risk analysis model(SD model)of rail transit PPP project is constructed in Vensim.PLE software.The validity of the SD model is confirmed by structural rationality check,model integrity check,integral difference analysis and parameter sensitivity analysis.Then,SD model is applied to the financing risk management practice of Wuhan rail transit line 12 PPP project.Through simulation analysis,the change of target risk due to time cumulative effect is reflected.On the macro level,the risk level of credit risk,operational risk and financial risk is high through the target risk rating,which needs to be focused on prevention and control.On the micro level,the key risk factors such as incomplete contract risk and insufficient earning capacity are identified through the sensitivity analysis of boundary risk.And put forward the corresponding risk prevention and control strategy according to the actual situation.Finally,the risk prevention and control strategy is substituted into SD model in the form of data to simulate the effect of risk prevention and control.The results show that the risk prevention and control strategy can weaken the target risk to a certain extent and has certain feasibility.It not only provides theoretical guidance for the prevention and control of financing risks of rail transit PPP projects,but also provides new ideas and methods for realizing dynamic risk management.