Spatial equity analysis on expressway network development in Japan: Empirical approach using the spatial computable general equilibrium model RAEM-light

The authors apply the RAEM-Light model to analyze the distribution of social benefits from expressway network projects from the viewpoint of spatial equity. The RAEM-Light model has some innovative features. The spatial behavior of producers and consumers is explicitly described and is endogenously determined by using econometric production and consumption functions. This model applies a slightly different concept than the traditional spatial computable general equilibrium model that does not depend on the input-output data. It is therefore well suited for analyzing detailed areas for which official input-output data are not available (i.e., its zones are subdivided into a neighborhood area level). In this paper, the authors analyze two expressway network scenarios. In Scenario 1, the regional economic impacts from the present expressway network are simulated. In this base case simulation, it is concluded that the present expressway network has a low score on spatial equity, in particular because of negative impacts on rural areas. In Scenario 2, the authors analyze the present and future expressway network case in rural areas. As compared with Scenario 1, negative impacts from the implementation of the expressway network are reduced, especially in rural areas. This comparative analysis quantified the effectiveness of the two network structures from the viewpoint of spatial equity. Theoretically and quantitatively comprehensive studies from the viewpoint of spatial equity on the effects of infrastructure development have not yet been sufficiently conducted; however, the results of the comparative analysis are promising for an economic assessment of the expressway networks from the point of spatial equity.