日本経済の空間的計量モデル(SPAMETRI)の適用による新幹線および高速道路投資の効果分析

抄録

We developed the Spatial Econometric Model for Japan (SPAMETRI) during the years 1970-1975. The analytical purpose of the model is to evaluate the interregional effect of a nation-wide transport invesemtnet project. The whole structure of SPAMETRI is divided into two major parts: Production-Expenditure Model (PEM) and Traffic-Transport Model (TTM). And the structure of SPAMETRI is relatively simple and ordinary, except for a unique concept of time distance or accessibility of a region. Nevertheless, because of the multi-demensional character of the model resulting from its interregional setting, the number of equation becomes extremely large.
The purpose of this paper is to apply SPAMETRI to the evalulation of the economic effects of Tokaido Shinkansen and Tomei-Meishin expressway construction. For this purpose, however, we cannot utilize SPAMETRI in original form. The reason is as follows. The timee series data from 1961 to 1973 are available for the economic and demographic variables, but only 1961-1970 data are available for the transprot variables. Therefore, the equations which contain some transrpot variables have to be estimated by the data for shorter periods. Because of this limitation together with other technical difficulties, the joint ex post simulation (final test) with the PEM and TTM is possible only for 1963-1968. However, a single ex post simulation with PEM can be performed with exogenous supply of time distance variables extrapolated backward by the available data. This single simulation with PEM was carried out for 1956-1963 years.
In order to evaluate the economic effects of Shinkansen and expressway constructtion, we performed simulation of six types. Numerical results of above simulations are summarized as follows.
(1) The benefit-cost ratio of Shinkansen construction investment is approximately 1.4 times of the ratio of construction investment in the ordinary railway. As to the costs of construction investment, both are equivalent. Compared with the ordinary railway, Shinkansen has only a little effect on the regional decentralization of income produced.
(2) The benefit-cost ratio of expressway construction investment is 1.755 times of the ratio of construction investement in the ordinary road. Compared with the ordinary road, the expressway has an effect on the regional centralization of income produced.