After the park concept had been imported from Western countries, it's been developed especially for children usage from the late 1960s in uniform design by Japanese government standards. Nowadays more than 70% of them holds by neighbourhood parks that are less than 2500 sqm filled with similar play facilities like a swing, a sandbox, and a slide.
In recent year, park-relevant policy actively focuses on improving its quality rather than increasing its quantity, by sharing park functions following local requirements among neighbourhood parks. At the same time, as technology are radically glowing and spreading, the movement of making basic statistics data open-source are getting active. It happens on the local municipality level as a moderate solution between park development by the bottom-up approach which consumes much time and budget of the municipality on the workshop and the top-down approach that has been done last decades. These actions possibly improve the transparency and accountability of government agencies and its planning of parks.
The purpose of this research is to evaluate possible scenarios for function sharing of neighbourhood parks at Adachi ward in Tokyo. Focusing on their project called "Park innovation project", which attempts to share the park functions in Adach ward, neighbourhood questionnaires had been carried out to classify park preferences based on attributes and the value weighting extracted by conjoint analysis. As a result, park preference at the target site has been classified into five typologies.
Based on the park preferences and location environment of each park, the decision-making tool for both citizens and municipality has been proposed to evaluate recent developments and scenarios on multi-criteria of social, environmental, economical and balance aspects. The decision-making tool simulates massive solutions for function sharing with filtering better solution by genetic algorithm, which could narrow down 450 representitive solutions from 1.35+E51 all possible solutions. Comparing the 450 simulation results with the evaluation values of existing parks, it is confirmed that the diversity of functions on present parks are not ensured. However, the improvement of function sharing develompent has been shown by the comparison between developed 9 parks and 28 existing parks. It is also suggested that the need for improved park evaluation by sharing the functions of neighbourhood parks in the region.
There is no solution maximizing all aspects however scenario prioritizing social aspect tends to comprehensively maximize other evaluations rather than scenarios prioritizing balance aspects nor economical aspects, which could easily be chosen by the municipality.
As a conclusion, trade-off among each evaluates aspect has been clarified above, which could bring a milestone towards rapid consensus making with high quality reflecting neighbourhood requirements. As the outcome of the research, the decision-making tool which could be a base of discussion has been proposed, and 450 function sharing scenarios are concluded into datasheets for the actual local workshop very shortly. Those achievements will contribute to actual urban design on public space and will lead to evidence-based park planning.
