Study Of The Combined Impact Of Parking Charge And Supply Policy Based On System Dynamics Theory

Reasonable parking supply and charge are essential for the regular operation of the traffic in the city center, but the actual effect after parking policy is often difficult to predict. The effectiveness of parking policy as a mean of transportation demand management has been confirmed by numerous studies. However, those studies only considered the influence of parking fee but ignored the parking supply, and most of the analytical models are static models and focused on aggregate demand, which couldn’t provide an intuitive decision-making basis for government decision-makers. So how to analyze the dynamic effects of different parking fees and parking supply policy to traffic state has becopme an urgent transportation problem. System dynamics is a modelling approach characterized by its capability of representing aggregate systems and capturing the dynamic complexity of their evolution, it can satisfy the dynamic evolution demand of the model while considering the combined effect of parking fee and parking supply, the model can make an dynamic assessment for the traffic state under different paking policies and obtain the optimization of parking fee and parking supply policy.This paper analyzed the combined effect of parking charge and parking supply through their working principle, and described the System Dynamics and its model approach, based on which we developed an evaluation model for parking policy using System Dynamics, studied at the effect of parking charge and supply policies to traffic speed. Composed of three interrelated subsystems, the model first summarized the travel cost of each travel mode in the travel cost estimate subsystem, then in the travel mode choice subsystem it predicted the new travel choice distribution based on the travel cost of each travel mode, the travel choice distribution was converted into traffic flow and sent into the traffic state evaluation subsystem which forecasted the future car speed based on BPR function and generated the new travel cost. The new travel cost would be sent into the model for a new cycle until the entire model reached a steady state. The model output traffic speed as the evaluation variable to represent the traffic state of the entire road network and provide a theoretical basis for the decision-makers.This paper took the centre area of Hangzhou Province as an example, the survey was designed based on the data that the model needed. The accurate of the model was verified by the survey data and the data of a business district called Wu Lin in Hangzhou from Hangzhou Traffic Congestion Index System, it is pointed that the relative error between the predict speed and the real speed is only 1.1 percent. The results indicated that the regular pattern of the traffic speed to parking charge can be showed well using the comprehensive evaluation model based on System Dynamics, and the model infers that reduce the parking supply in the core area will increase its congestion level.