双城系统的聚集外部性、拥堵外部性和最优收费

Agglomeration Externalities,Congestion Externalities and Optimal Toll for a Two-city System

聚集外部性有利于提高双城系统的经济发展,但同时也会产生城际通勤拥堵外部性,为缓解城际通勤交通拥堵,可以利用最优收费调节交通供需关系。本文研究了城际通勤最优收费水平随交通拥堵外部性和聚集外部性的变化规律,建立双城系统的空间均衡模型和社会最优模型,分析居民的职住分布,得到城际通勤最优收费水平。结果表明,因为聚集外部性的存在,城际通勤最优收费水平可能大大低于交通拥堵外部性成本;当聚集外部性固定时,城际通勤最优收费水平随交通拥堵外部性的增大而增大;当交通拥堵外部性固定时,随着聚集外部性的增大,城际通勤最优收费水平先增大后减少;当聚集外部性和交通拥堵外部性同时变化时,随着聚集外部性的增大,交通拥堵外部性的减少,城际通勤最优收费小于零,此时,城际通勤时可以得到补贴。

The presence of agglomeration externalities contributes to the enhancement of economic development in a two-city system,while also giving rise to congestion externalities associated with intercity commuting.In order to alleviate the traffic congestion in intercity commuting,the optimal toll can be used to adjust the relationship between traffic supply and demand.This paper investigates how the optimal toll level for intercity commuting varies with the magnitude of traffic congestion externalities and agglomeration externalities.The paper develops spatial equilibrium and social optimum models for the two-city system,analyzes the distribution of employment and residence for households,and obtains the optimal toll level for intercity commuting.The results show that the optimal toll level for intercity commuting may be significantly lower than the corresponding traffic congestion externalities cost due to the presence of the agglomeration externalities.When considering fixed agglomeration externalities,the optimal toll level for intercity commuting increases with congestion externalities.When considering fixed traffic congestion externalities,the optimal toll level for intercity commuting initially rises and then declines as agglomeration externalities increase.When agglomeration externalities and traffic congestion externalities change at the same time,as agglomeration externalities increase and traffic congestion externalities decrease,the optimal toll for intercity commuting is less than zero,at which point intercity commuting is subsidized.