Analysis of taxi services with search frictions and congestion externality.
详细信息
文摘
The equilibrium properties of an aggregate taxi market are investigated using a general bilateral searching and meeting function which characterizes the search frictions between vacant taxis and unserved customers. Three specific issues are analyzed for meeting functions that exhibit increasing,constant and decreasing returns to scale. Firstly,service quality in terms of customer wait/search time and average profit per taxi are examined jointly in relation to taxi fleet size,and a Pareto-improving win-win situation is identified,where an increase in taxi fleet size leads to improvements in both service quality and market profitability. Such a Pareto-improving situation is found to emerge if and only if the meeting functions show increasing returns to scale. Secondly,the properties of the socially optimal solution are examined. It is found that the taxi fleet size should be chosen such that the total cost of operating vacant taxis equals the total cost of customer waiting time multiplied by an asymmetric factor of the meeting function,and that taxi services should be subsidized at social optimum only when the meeting functions show increasing returns to scale. Thirdly,the Pareto-efficient services are examined for trade-offs between social welfare and profits in the light of partially conflicting objectives of the public sector and the private taxi firms using a bi-objective maximization approach. The taxi utilization rate and the customer wait/search time or service quality are proved to be constant along the Pareto frontier and equal to those at social optimum if the meeting functions show constant returns to scale. Extensions are made to the cases with increasing and decreasing returns to scale. This thesis further incorporates both bilateral taxi-customer search frictions and congestion externality into the economic analyses of the equilibrium properties of taxi market. We take account of congestion externalities by adopting a realistic distance-based and delay-based taxi fare structure. We first investigate comparative static effects of regulatory variables of taxi fare and fleet size on the market,and then examine the properties of the Pareto-efficient solutions for simultaneous maximization of social welfare and taxi profit in the congested market. A Structural Equation Model SEM) is applied to estimate the returns to scale in a Cobb-Douglas type bilateral searching and meeting function which characterizes the search frictions between vacant taxis and unserved customers. Number of taxis,taxi fare,population,average occupied taxi journey time and disposable income are used as exogenous variables； while customer demand,average customer waiting time and average taxi waiting and cruising time in search of each customer are used as endogenous variables. These variables are coupled together through the SEM whose parameters are estimated from the Hong Kong annual taxi survey data. Our calibration results show that urban taxi services in Hong Kong exhibits an increasing return to scale. The established SEM model can be used to obtain regulatory information useful for decision making,such as the impact of the restriction over the number of taxi licenses and the fixing of taxi fare structure.