Vol. 38 Autumn 2006

Marunouchi and Yaesu districts, located on the east and west side of Tokyo Station, are undergoing a series of new developments, while Tokyo Station is regaining its original appearance.

The area around Tokyo Station. Marunouchi occupies the space between the luscious greenery of the Imperial Palace and Tokyo Station, with Yaesu in the foreground.

Development of the Historic Business District of Marunouchi Located near the Imperial Palace, Marunouchi was until the end of the Tokugawa Shogunate the home of numerous mansions belonging to important daimyo (hereditary feudal noblemen). Following the elimination of the daimyo through reforms after the Meiji Restoration, at the end of the 19th century the government ceded the land for private development as a business district. The English-style brick buildings that subsequently filled the area represented the first modern architecture in Japan. In 1914, the Tokyo Station building was built near the Marunouchi district as Tokyo's new central station. It is admired to this day for its magnificent outline, which symbolizes the modernization of Japan. Numerous American-style office buildings were built along the area in front of Tokyo Station around the same time. The Marunouchi Building (dubbed the "Maru-Biru") was erected in 1923 using the latest construction technology at that time. The Maru- Biru was a new style of office building that incorporated commercial outlets which were open to the public, and survived the Great Kanto Earthquake, which occurred that year. After World War II, with most of the office buildings having been destroyed or occupied by the Allied Forces, there was a severe shortage of office space. A series of new office buildings were built along Marunouchi's streets as Japan's economy recovered and quickly grew during the 1950s and 1960s. The area once again developed into an attractive business district. Tokyo Station and the surrounding areas were also renovated to accommodate more trains. Kajima was involved in many of the construction projects in and around Tokyo Station, including the platform for the Tokaido Shinkansen, the central artery of Japan's rail network.

Tokyo Station's red-brick facade is a symbol of modern Tokyo.

Many high-rise buildings have been developed in the Marunouchi district over the past few years (Left: 1990; Right: Present day)

Revitalizing the Marunouchi District Although the Marunouchi district held its status as Japan's premier business district with a series of head offices of Japan's leading corporations, buildings erected under old building construction codes, which limited the height of buildings to 31 meters (102 feet) to protect against earthquakes, were showing their age. The Marunouchi Building, the best-known office building in the district, was rebuilt in 2002 as a high-rise structure with the aim of creating a multipurpose district that anyone could enjoy. Other redevelopment projects such as the Tokyo Building have progressed in surrounding areas, transforming the vicinity from a simple business district to a wellrounded town displaying the latest fashions and information trends.

Interior of the Tokyo Building

Tokyo Building Transformed: An Advanced Space The new Tokyo Building, featured on our cover page, was erected on the south side of Marunouchi, with 33 stories above ground and four below. The original nine-story building, built soon after the war in 1951 and one of the best-known faces of the district, was rebuilt as a high-rise office incorporating the latest technology. The lower floors contain shops and restaurants, while the upper floors provide office space. An underground network linking the building with Tokyo Station greatly increased convenience and improved customer drawing power. Kajima proposed a 24-hour rapid construction method that would appreciably shorten the construction period from the normal 36 months to 30, providing significant savings in terms of cost and time. Kajima also provided technology to increase safety, incorporating the Water Screen fire prevention system (see box) and HiDAX-e seismic control system.

Artist's rendition of the completed Yaesu redevelopment. The southern and northern towers will be completed in 2007.

Yaesu District: A New Face for Tokyo The Yaesu district on the east side of Tokyo Station also has a long history as a business district, and is likewise a commercial district filled with department stores and an extensive underground shopping mall. Nearly 30 years ago, at the site where its former head office building had stood, Kajima constructed Japan's first large-scale bookstore, the Yaesu Book Center, which continues to be frequented by readers. Yaesu is now undergoing a large-scale redevelopment project in which Kajima is participating along with railroad companies and real estate firms. For this project, Kajima is constructing twin high-rise towers on either side of the promenade in front of the station. A wide, covered boardwalk will provide a link between the two towers.

Recreating the Original Station Building as a New Face Simultaneous with the redevelopment of the Marunouchi and Yaesu districts, another project has now gotten underway to restore the Tokyo station building, which was partially destroyed during World War II, to its original appearance when it was built in 1914, with work scheduled for completion sometime around 2010. The Tokyo Station, Marunouchi and Yaesu districts continue to evolve as Japan's premier station and districts and will create a new face for the capital city.

Safety Systems in the Tokyo Building The Tokyo Building has been installed with a Water Screen fire prevention system, which compartmentalizes the building with curtains of fine water particles. This system, which was jointly developed by Kajima and Hochiki Corporation, has received certification from the Ministry of Land, Infrastructure and Transport, allowing it to be installed without the need for complicated approval procedures. The Water Screen creates fire-containing compartments using a series of special spiral heads arranged in a row to spray fine particles of water 200 microns in size. Because it is a water curtain, escape, rescue and firefighting routes are not blocked. The system can also create curved or cross-sectional compartments where fire shutters and other systems would be impractical. It is a revolutionary fire prevention system that vastly expands the possibilities of spaces. Using the Water Screen to compartmentalize urban areas where many people pass through will help contribute to the creation of safe cities. Artist's rendering of the Water Screen system Water Screen system test

Vol. 38 Autumn 2006 Transformation of Tokyo's Signature Districts and Revitalization of the Heritage Kajima around the World

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