Theme 3
SDGs and Sumitomo: Community Development

Even in the central districts of Tokyo there is unused or underused land*, densely built-up quarters crisscrossed by alleys exposed to high disaster risks, and communities lacking vitality and frequented by few people. Individuals or residents’ associations acting alone cannot transform these areas. Sumitomo Realty & Development has vigorously engaged in urban redevelopment since the mid-1970s as a comprehensive developer coordinating the rights and interests of landowners, always with the aim of resolving the issues confronting communities and enriching their functions.

In pursuing redevelopment, Sumitomo Realty & Development emphasizes community co-creation hand in hand with the residents of communities. Through in-depth discussion with landowners to identify residents’ lifestyles and the issues confronting the community, the company endeavors to reach a consensus so as to promote community development aligned with the residents’ desires and aspirations while considering profitability.

Forming a consensus is the most time-consuming and challenging task because of the differing interests of the various parties involved. Starting with discussion with landowners, the company cultivates their understanding of the contemplated redevelopment, formulates a redevelopment plan, and executes the project. Always working with communities to resolve the issues they face, Sumitomo Realty & Development’s pursues urban redevelopment conducive to vibrant sustainable communities that offer residents’ safety and security and are frequented by many non-residents.

Two excellent examples of Sumitomo Realty & Development’s people-centric approach to urban redevelopment in central Tokyo are Koraku 2-chome East District and Koraku 2-chome West District in Bunkyo-ku, Tokyo, adjacent to JR Iidabashi Station. Fire could have spread easily in such a tightly packed area crisscrossed by alleys and the nearby river posed a risk of flooding. First proposing redevelopment of the east district under the Urban Renewal Act, the company held the first workshop with landowners in 1987, proposed the plan, listened to their opinions, and refined the plan in light of those opinions so as to resolve the issues etc. Although some landowners initially raised objection, the consent of all the landowners was eventually secured and the Sumitomo Fudosan Iidabashi First Building was completed in 2000, a complex of offices, residences, and commercial facilities. A densely built-up area of low-rise wooden houses exposed to high disaster risks was transformed into Japan’s first building equipped with seismic isolation devices installed between the upper and lower floors. Apartments on the upper floors were allocated to people who had been living in the area prior to redevelopment and those who had owned business in the area opened offices and shops on the lower floors. The residents resumed their lifestyles.

In the 1980s, aging infrastructure such as deteriorating roads and bridges had a serious impact on the economy and people’s lives in the U.S. ‘America in Ruins: The Decaying Infrastructure’ written by Pat Choate and Susan Walter was among the bestselling book in Japan at the time. Five decades since the end of high economic growth, concerns about aging infrastructure pointed out in the book have been raised in Japan as well, and building a sustainable community has become a pressing issue.

Amid such circumstances, Sumitomo Mitsui Construction Co., Ltd. (SMCC) has been focusing on the precast concrete method, which involves fabrication of concrete elements offsite that are then combined at construction sites. Compared to the cast-in-place concrete method applied at the construction site, merits such as quality stability, labor-saving, shorter construction period, energy-saving at the construction site, and minimizing dust, debris, and noise for the neighboring communities can be achieved.

SMCC embraced the precast concrete method at full scale in the early 1990s. As concrete fabrication technology progressed, high-strength concrete became suitable for high-rise buildings higher than 60 meters, which was considered difficult in the past. In particular, for buildings emphasizing better living conditions, such as super high-rise buildings, a Reinforced Concrete (RC) structure is more suitable than a Steel (S) structure owing to less vibration and superior fire resistance, and thus as demand for higher concrete strength increased, so did demand for the precast concrete method. Moreover, after the bursting of the economic bubble in Japan, and facing the decline in the number of skilled engineers specialized in the onsite casting of concrete, use of the precast concrete method increased in order to maintain quality while achieving labor-saving.

The precast concrete method called SQRIM (Sumitomo-Mitsui Quick RC Integration Method) is the current expertise of SMCC, a method in which the main structural elements such as joints of structural parts including columns and beams are fabricated as a single precast unit. Unlike wall parts that only block wind and rain, the structural elements such as columns and beams require sophisticated architectural designs including weight and dimensional designs. For example, in order to join a column and beams configured in a complicated manner, 20 steel rods, each 40 mm in diameter, must be precisely slotted into position without any deviation. Thus, SQRIM requires advanced technology throughput the process from the design stage to installation. Having its own in-house precast plant, SMCC has a great advantage. Handling the entire process all the way from the design stage to installation continually accumulates knowhow and thus enables accomplishment of the most complicated orders (construction).