Research background
In Japan, the unprecedented population decline is proceeding. Therefore, the construction of a sustainable compact city is an urgent issue in local cities. With the amendment of the Urban Renaissance Special Measure Law, which came into effect in 2014, it was possible to formulate the location adequacy plan that integrates urban planning and private facility induction. In formulating the plan, the setting of the city function instruction area and the residence instruction area is required. It is also essential to set target values for problem solving and to quantify expected effects due to achievement of goals. As of June 5, 2018, 164 municipalities have already formulated plans among 1,712 municipalities nationwide. In the future, it is certain that plans will continue to increase. On the other hand, analyzing the plan that is formulated is a problem that the viewpoint of reducing CO2 emissions is insufficient. There is no doubt that balanced policies, including not only environmental aspects but economic aspects, are important for thinking about the compact city. For this reason, this study aims to devise Low Carbonization Eveluation Method that supplements the setting method that is generally adopted in the study of Residence Instruction Area.
Research method
The Ministry of Land, Infrastructure and Transport aims at the "compact city + network" that realizes a virtuous circle through collaboration between a site location plan and regional public traffic restructuring plan. Meanwhile, in local cities, public transportation facilities are not satisfied as in the metropolitan area, the degree of dependence on cars is extremely high at present. In the future, rapid development of automatic driving technology is expected, there is a high possibility that this trend will not change significantly even if the aging society progresses. In this study, commuting distance by automobiles with high dependency in local cities was chosen as an evaluation indicator. Utility as an evaluation indicator was clarified through verification of CO2 emission reduction effects resulting from shortening commuting distance due to centralized urban areas. Also, the low carbonization evaluation method has been devised that can extract districts contributing to low carbonization.
1) Estimation of commuting distance
As an effect that can be expected by consolidating employees into residence induction area, the method of estimating CO2 emissions associated with automobile commuting by employees for each town and street.
2) Setting of the “low carbonization area”
Based on the commuting distances, a reference value was set that can discriminate towns and streets which contributes to reduction of CO2 emissions. Next, by utilizing the reference value, a layer related to low carbonization (low carbon contribution area) was set after dividing all towns and streets into multiple areas according to reduction contribution degree.
3) Comparative verification between low carbon contribution area and actual living induction area
A method of utilizing the Low Carbonization Evaluation Method was devised through comparative verification between the low carbonization area and the residence instruction area under consideration in research target cities.
In the future, municipalities that are working on the formulation of the location adequacy plan can utilize as a logical basis when considering the setting of the residence instruction area, and municipalities that have already formulated plans can use as a basis for review every five years.
