A Derived Demand Function for Freight Transportation
将运输视为生产过程中的投入，利用超越对数成本函数估计铁路和卡车的派生需求，发现零担货运中铁路与卡车基本独立，且铁路需求价格弹性较高，表明全面提价可能不利而选择性降价更优。
An attempt has been made to improve upon existing specifications and estimations of freight demand by treating transportation as an input in the production process and estimating the derived input demand equations for rail and trucking associated with a general translog cost function. This estimation method also recognizes that rates and shipment characteristics are jointly dependent and takes this inter dependence into account in estimating the demand functions. Two tentative conclusions emerge from the findings of this paper. First, at least with respect to less-than-truckload (LTL), rail and truck transportation are largely independent. Therefore, relatively little modal misallocation of resources between rail and LTL trucking should result from ICC policies that attempt to maintain the value of service pricing structure. Second, the estimated own price elasticities of demand for rail services were sufficiently high to indicate that the railroads might not benefit from blanket rate increases but could benefit instead from selective rate cutting. It is noted that the unique methodology employed and the empirical findings described in this paper need to be verified using different data and different time periods.