In March 2019, a consortium that included Obayashi was selected as a prospective project developer in a proposal-based competition sponsored by Yokohama City, and land owned by the city near Shin-Takashima Station on the Minato Mirai Line and roughly eight minutes on foot from Yokohama Station was transferred for the purpose. A construction of a large-scale multipurpose complex with a total area of over 180,000 square meters and boasting a 30-story West Tower and a 16-story East Tower will be developed on this land.

The consortium consists of four companies with different core businesses: Obayashi, Keikyu Corporation, Nippon Steel Kowa Real Estate Co., Ltd., and Yamaha Corporation. Our strength is its abilities to create new synergies by bringing together each company's expertise and know-how.

This is the first time that Obayashi will serve as the managing company in a large-scale joint development project with other companies. Obayashi is determined to capitalize on its position as developer, designer, and as a construction company to reduce costs and create environmentally friendly, attractive facilities through the introduction of the latest technologies and other means. To those ends, we are cooperating with the consortium members on a daily basis.

To minimize the volume of excavation required, the basement floor was only one floor, and the underground space was kept to an absolute minimum to reduce the volume of construction work.

Girder shoring was used to support the earth-retaining walls during excavation, and a bottom-up construction method was adopted to build the underground frame upwards from the foundation's footing beams. Unlike with the top-down construction method, in which underground and aboveground construction can be carried out at the same time, it was therefore essential to shorten the underground construction period. However, because the land was soft, it was also necessary to install girders at a fine pitch in order to control any displacement of retaining walls.

To increase construction efficiency, girders were arranged in one direction in a concentrated layout to secure large workspaces, while corner angle braces and ground anchors were used at the ends of the excavation area.

Given the proximity of the West Tower to the public road, it was not possible to secure the space required to install the ground anchors needed for cantilever retaining. So the design of the underground frame was also changed to facilitate its installation. The advantage of design-build contract is that you can incorporate builder side's opinions into the design to reduce construction time and costs.

• *1 Clean-Crete
  A type of concrete which can reduce CO2 emissions by a maximum 80% by replacing cement with industrial by-products such as fine powdered slag from blast furnaces, which do not generate much CO2.

Work style reforms are often judged on working hours, but Project Director Sato feels that "it is important to ensure that employees experience great job satisfaction and feel comfortable in the work. That's why we first created a positive office environment."

The construction site office was equipped with all the latest fixtures and fittings to improve the work environment. We also came up with various ways of creating an office environment in which people could relax, communicate easily, and concentrate on their work. One example of this was our decision to create zones in the construction site office. The office space is divided into an active zone, a solo work zone, and other specific spaces.

Keeping the office exclusive to authorized personnel helps enhance concentration and inspire vigorous horizontal communication in each of the specific zones. This reduces the emergence of gaps between each work and makes for smoother coordination across the site.

In addition to improving the office environment, we are also actively utilizing ICT tools. As a rule, we circulate information electronically on eYACHO, a construction management app for construction sites, and share information with relevant parties using Microsoft Teams to facilitate a paperless operation.

All of these measures help create an environment in which employees can concentrate on their work and enjoy a greater sense of fulfillment. Ultimately, these innovative measures have boosted productivity considerably further than was initially expected. "The dynamic excitement of building something on a site is unique to the construction industry. I believe that we have to adjust our workplaces flexibly in order to create environments in which employees get to truly enjoy that sense of fulfillment," says Mr. Sato.