Changes in the network centrality of greenways in housing areas under redevelopment in Tsukuba Science City

Abstract

In some Japanese New Towns (NTs), which were constructed from the 1960s to the 1970s by the Japan Housing Corporation, housing areas were integrally designed with open spaces such as greenways and parks, in order to provide pleasant corridors and nearby outdoor spaces for residents. However, redevelopment projects have been underway for some areas in NTs, conducted mostly by private developers. The shift in developers has also led to a change in the block design, which now has a closed layout. This weakens the residents’ connections to the unchanged open spaces. This study aimed to reveal the changes in the network centrality of greenways in redeveloped housing areas in Tsukuba Science City. To do so, we compared the network centrality of greenways before and after redevelopment, using three indices (Reach, Betweenness, and Straightness) through Urban Network Analysis in ArcGIS. The results show that the network centrality of greenways generally decreased after redevelopment. Although the network centrality primarily decreased around the former housing sites, it increased in the vicinity of several former housing sites as well. Additionally, changes in the network structure were found in some case studies that were based on the pattern of changes in the types of houses, such as condominiums or single-family homes.