Study On Cost And Benefit Of Expressway PPP Project Based On System Dynamics

With the rapid development of China’s economy,the construction of expressways is becoming more and more perfect.Meanwhile the road network system for interconnecting major and medium cities has been initially established.The expressway lines currently planned to be built are mainly supplements to the existing road network system.Most of their construction sites are located at the junction of provinces and cities with mountains and rivers,which makes the project go with a high proportion of bridge and tunnel construction as well as an uncertainty about traffic volume.Therefore,the government often encounter many problems in the investment and construction of such projects,such as high challenge in engineering,a huge amount of investment,and a uncertainty about return rate.To a certain extent,the use of PPP(Pubic-Private-Partnership)financing mode to introduce social capital can alleviate the government’s financial burden.As the PPP mode is a mechanism of multi-party cooperation,there is a certain conflict of interest between the government and the social capital.When planning projects,government pays more attention to the social benefits generated by expressways,while social capital is more concerned about economic benefits.Based on this phenomenon,this article combines the theory of system dynamics,starting from the internal factors affecting the cost and benefit of expressways,through analyzing the financial net present value,dynamic investment payback period,benefit-cost ratio and other indicators,exploring the premise of balancing costs to achieve the maximum benefit for both public and private parties.The specific research contents are as follows:First,through literature review and theoretical research,conduct an in-depth analysis of the concept,characteristics and project operation process of the PPP model.On this basis,analyze the characteristics and advantages of expressway projects under the PPP model;combine expressway PPP projects and use the life cycle cost theory of construction projects to analyze the composition of expressway PPP projects;comprehensively introduces the basic concepts of system dynamics theory,modeling procedures and the advantages of studying complex economic problems.Secondly,discuss the composition of costs and benefits of expressway PPP projects,summarize the calculation principles that affect various costs and benefits of expressways,identify and determine the main factors affecting the costs and benefits of expressway PPP projects,and quantify indirect benefits of expressways through special functions influence,lay the research foundation for subsequent modeling.Then,after identifying the main factors and determining the calculation method,analyze the internal connections between expressway PPP project systems,establish a causal feedback loop for qualitative analysis of expressway PPP projects and a flow diagram model for quantitative analysis;use the DYNAMO language to establish the system equation of each variable.Completes the construction of the mathematical model.Finally,taking the G Expressway PPP project as a case,combined with the actual data of the engineering project,complete the variable assignment and related debugging of the established system model,use professional software to simulate the case,and do multi-level and multi-angle research on the simulation results.Select key factors for sensitivity analysis,and explore methods to approaches for all parties involved in the PPP project to maximize benefits under the premise of balancing costs.