2017 Volume 82 Issue 739 Pages 2305-2311
Previous studies have shown that a high proportion of wooden main halls completed in the Edo Period or earlier still existing today. Thus, when estimating the average usage period of main halls, it is believed to be necessary to consider not only the usage period of the previous main halls that have already been rebuilt, but also the usage period of the current main halls to date.
There is prior research using survival time analysis to estimate the usage period of buildings, and the Kaplan-Meier method used for analysis including censored data (observed data on buildings still in use for which the lifetime is not determined) is used in such research, and this research also uses the same method of analysis.
As a result of survival time analysis of wooden main halls of temples nationwide under the conditions of complementing lost data by two times, it was found that the average usage period is estimated to be 235 years, which is 100 years longer than the usage period based on the arithmetic average already reported. By region, Hokkaido and Tokyo are particularly short at 78 and 119 years, while the average usage period in Kyushu is 173 years, 60 years less than the national average. Also, the five other regions (Tohoku, Chubu, Osaka, Chugoku and Shikoku) fell in a range between 210 and 273 years, comparatively close to the national average.
Current wooden main halls included local cultural resources, and the estimated average usage period of these was 504. This is more than double the average for wooden main halls as a whole, indicating that the usage period of cultural property is particularly long in cultural resources.
As described above, survival time analysis was performed to reveal a more accurate actual condition of the usage period of main halls and the regional differences thereof.
This research is focused on wooden main halls of Buddhist temples from a variety of eras extending to the present including those that were mainly completed prior to World War II. The results of this statistic and quantitative research indicate that even normal wooden main halls can withstand a considerable passage of time by conducting ongoing repairs if it is believed that there is a much intent to continue using them.
