سنجش ارزش زمان سفرهای باربری و مزایای آن براساس اطلاعات بازار

This paper focuses on how value of time and its accrued time saving benefits for freight trips can be expressed and measured in terms of market information such as freight fee, freight time, observable freight service consumption and observable freight service production within a framework of general equilibrium rather than individual user analysis which most previous studies adopt. In order to satisfy the weak complementarity assumption, we specifies freight time externality as product form of quality index of freight time and freight consumption Sh(t)x and S0(t)X into the utility function of non-business users and production function of business users, respectively. And for freight operators the product of quality index of freight time and labour and capital inputs S(t)l, S(t)k are introduced into the production function of freight operators. Then we define VOT as marginal substitution rate between price and time and expressed it as the freight service fee per freight time multiplied by the elasticity of quality level indicator with respect to freight time for each of non-business and business users, respectively. The freight service providers’ VOT is expressed as average labour and capital cost per freight time. Thus we can measure three VOTs in terms of market information such as freight fee, freight time and average labour and capital cost and the elasticity of quality level indicator with respect to freight time although we need to estimate quality index of freight time by estimating freight demand functions of users. Next we derive an “origin” formula to measure social freight time saving benefits including its repercussion effects expressed by the change in equilibrium freight price, wage and capital rent, where we adopted the concept of equivalent variation as the social benefit definition. The proposed origin (or shortcut) formula is the weighted general equilibrium consumers’ surplus of the freight demand multiplied by VOTs with respect to freight time. The weight after the change can be approximately expressed as 1 + (income effect of marginal freight time saving benefit for non-business), so that it is also possible to calculate from the market information. Furthermore VOT to be applied to the benefit measurement formula is a sum of VOT for shippers and operators. Therefore we can say that conventional trapezoidal formula with the weight of one and VOT for only operators underestimates the benefit in two points. First is missing the weight eBm and second is neglecting VOT for shippers.