Coal-producing areas experienced declines ahead of the rest of the country. We believe that clarifying transformation patterns of those areas will provide knowledge that will contribute to the planning of residential areas in the shrinking society. However, to understand the shrinkage process, it is necessary to understand the peculiarities of the formation mechanism of coal mining settlements. Therefore, this study aimed to reveal the construction process of coal mining company housing in the Mitsui Miike Coal Mine which is a representative example.

　The methodology is as follows. we studied the construction process of coal mining company housing by the historical records of Miike Mining and Miike Port Office, Company Housing Registry (Shataku Daichō), the information of architectural approval applications, documents of Teruo Takematsu, data of the applications for building confirmation, and Company Housing Plan of Miike Mining. Second, we divide the construction process of coal mining company housing into periods based on the social condition, and developments of the coal mining industry and coal mining company housing areas. Third, we plotted the construction process of coal mine company housing on the map for each period category.

　Through this study, we made the following things clear; 1) In Mitsui Miike Mine, the construction of coal mining company housing can be divided into nine periods: Phase 1 (1889-1902): the founding period, Phase 2.1-2.1 (1903-1924): the southwest move period, Phase 3 (1925-1935): the stagnation period, Phase 4 (1936-1944): the construction promotion period (the wartime regime), Period 5 (1946-1948): the construction promotion period (the postwar reconstruction), Phase 6 (1950-1958): the intermediate period between increased production and decline, and Phase 7 (1961-1997): the decline period.

　2)In Phase 1, construction activities were taken place near the mine shafts near the outcrop. In Phase 2.1, construction activities moved to the south with the mine shaft development (coal mining company houses for officers were built near the office and the port). In Phase 2.2, construction activities of coal mine company housing for miners moved to the southwest with the mine shaft development. In Phase 3, construction activities moved to the west even under the recession. In Phase 4.1, construction activities of coal mine company houses for miners began to be observed in the east and west regardless of the mine shafts' location. In Phase 4.2, coal mining company houses were built in the east and west regardless of the location of mine shafts. In Phase 5, construction activities were carried out over a wide area from east to west, regardless of the mine shaft's location. In Phase 6, construction activities were carried out over a wide area from east to west. In Phase 7, construction activities were concentrated in the western part near the mine shafts. In the company housing plan, the policy was to maintain the coal mine company houses in the northwest near the mine shafts.

　From the above, we can infer that we can classify the formation process of coal mining settlements into (1) the modernization process, in which coal mining settlements move along the geological structure, (2) the production increase process, in which coal mining settlements expand under the influence of social conditions and national policy, and (3) the decline process, in which coal mining settlements shrink again along with the geological structure.

　Following the previous theses, which clarified the intention changes for the entire city and for each reconstruction method and place, this study clarifies the influence of resident attributes on intention changes.

　Finally, the authors clarify how affected households determined and changed their intentions regarding housing recovery according to the household age, economic conditions, and household composition. The following is a summary of the findings of this study.

　Regarding initial intentions for housing recovery method, households that intended to reconstruct by “Collective relocation project for disaster prevention” or “Housing reconstruction on their own” were characterized as working family households which are middle-aged, large family and standard-level income. Having sufficient financial resources and requiring a certain amount of residential space, these households intended to reconstruct their housing as owner-occupied detached houses. On the other hand, the households that intended to reconstruct by “Disaster restoration public housing” were characterized as elderly households who had finished their prime working years which are 60s and more, small family, and low-level income. Not having the financial capacity and not needing a large housing area, these households are thought to have expressed intentions to reconstruct their housing in rental housing.

　When it came to the final intention, there was no difference in the percentage of intentions by “household age at the time of answer”. With regard to the other residential attributes, firstly, the intentions for reconstruction in owner-occupied detached houses were generally the same as initial intentions, however, some households changed their intentions and choose a different reconstruction method depending on their occupation. Specifically, on the one hand, “self-employed” households tend to choose “Housing reconstruction on their own” which has flexibility in location, on the other hand, “civil servant” households tend to choose “Collective relocation project for disaster prevention” which has the economic advantage. Secondly, the initial tendency was stronger for “Disaster restoration public housing”. This is due to the fact that small and low-level income households with financial and family reasons abandoned the reconstruction by owner-occupied detached houses and changed their intentions to “Disaster restoration public housing”. In addition, "fishery" households, a characteristic occupation in Ofunato City, consistently expressed their intention to “Collective relocation project for disaster prevention” from the beginning, which may be due to the influence of the location of the project, which was mainly conducted in fishing villages. This point is also supported by the analysis of "typical attribute types". The households that initially “No answer” were relatively younger, single, and low-level income households that had little intention to rebuild by owner-occupied detached houses and did not need to actively seek assistance.

　In terms of intentions for the housing recovery place, households that initially moved from “Outside the city” and finally moved into “Inland area” tended to be younger and had low-level incomes. These households that relocate from their previous residence are considered to be more mobile and it is relatively easier for them to rebuild their homes in their new residence.

　In this study, the authors conducted research of the repairing cases of flooded detached houses, aiming to clarify the relationship between flood damage and repairing method that were carried out subsequently of flooded houses.

　The authors made technical interviews with a regional building contractor who repaired flooded detached houses in Mihara City, Hiroshima Pref., which is one of the areas affected by the heavy rains in July 2018 (Heavy rains of July Heisei 30). They conducted a case study of 11 selected houses and examined what repairing work were performed focusing on whether replacement or continuous use of each building part of the houses was selected. The results indicate that there is little difference of repairing work between construction types of house and that repairing methods are likely to be characterized by flood level.

　With collected data of construction cost of the cases, the authors conducted quantitative analysis between direct construction cost and degree of flood damage. As a result of a linear regression analysis, a simple regression model using flood volume (m3) as an explanatory variable, which is the product of repaired floor area (m2) and flood level (m) above floor, was evaluated as intuitively easy to comprehend and with high compatibility.

　The authors considered simulated repairing method of a standard model house at different four flood levels to verify differences of repairing method and construction cost fluctuation depending on height of flood levels. The elevation from underfloor to 0.2m height above floor was found to have the most impact on the overall increase in construction cost from underfloor to 2.0m height above floor, because sanitary equipment, floors, internal fittings and furnitecture are to be replaced at the same time. The elevation from 0.9m to 2.0m above floor, the cost increase due to the renewal of windows, front doors and staircase are particularly large. These construction works that occur collectively when a flood level exceeds a certain height would contribute to the discrete increase in cost. In contrast, the range of the internal wall to be replaced enlarges as the flood level gets higher. Therefore, the cost from 0.2m to 0.9m above floor increases continuously.

　Comparing the predicted values and the estimated values of the model house, the predicted ones are particularly larger at 2.0m above floor although it was roughly fitted in the range of 0.2m to 0.9m. Such differences are considered caused by discrete increases in cost described above and the sample data including additional cost. Further studies are needed in the future to refine the predict model.

　The obtained findings indicate the repair methods performed subsequently of flooded detached houses are likely common depending on the flood level. The normal repairing methods presented in this study can be used as a basic plan for residents and construction contractors to consider repairing methods. It is expected to be used as a starting point for clearly discussing what repairing method will be optimal according to their budget situations and future living style.

1.Introduction

Aging of public facilities, declining population and increasing local government finance have been questioned conventionally. From such as situation, In April 2014, the Ministry of Internal Affairs and Communications requested municipalities to formulate a "Comprehensive Management Plan of Public Facilities and Infrastructures". In the plan, the facility reduction target and basic policy are described using uniform calculation of renewal and renovation expenses. However, the construction transition of public facilities differs from municipality to municipality, and the uniform calculation does not provide an appropriate analysis.

2.Purpose of This Study

The purpose of this study is to consider public facilities improvement policies according to the differences of construction transition.

3.Research Method

The method is classifying in the transition patterns of target municipalities by cluster analysis. Then, we estimate renewal and renovation expenses and reveal features and problems by each cluster.

4.Research Result

The results of this study are summarised below.

1) By constructing the database of public facilities, it becomes possible to compare between municipalities.

2) The construction transitions of public facilities are classified into 4 types. These types are Economic growth period peak type, Early peak type, Two peaks type and Continuous construction type.

3) The transitions of renewal and renovation expenses are different for each type, and improvement policies such as reduction and leveling are also differ from type to type.

・ Municipalities that constructed public facilities in particular from 1950 to 1970 need to reduce public facilities quickly because it is difficult to level out renewal and renovation expenses due to early renewal period and many facilities that have not been renovated.

・ Municipalities that built intensively public facilities around 1980 have to level out expenses by renovating the facilities that have not been renovated and accelerating renewal time during the period up to about 2060. It is effective in reducing school facilities, government office, parenting support facilities and public housing built around 1980.

・ For municipalities that have continued to construct public facilities since 1990, it is desirable to consider renewal and renovation together and level out the expenses including the next about 40 years. They need to investigate surplus public facilities except school facilities and plan for reduction in those facilities.