Vol. 36 Spring 2006

A rich and varied cultural heritage is born, cultivated, and preserved over the centuries in Japan. We have a duty to pass this on to the next generation. But many of our important cultural properties have deteriorated with age or been damaged in man-made or natural disasters. Sophisticated construction technologies play a key role in securely preserving and restoring these endangered cultural assets. Earthquakes have been especially damaging in Japan, and Kajima has employed a range of techniques and materials to strengthen structures and help ensure the survival of both historical buildings, and the museums that house cultural treasures. In this issue, we introduce some of the renovation and reconstruction projects in which Kajima has played an important part in passing on our cultural heritage.

Renovating Japan's Cultural Assets Honmonji Temple Renovation of the roof of the main hall of Ikegami Honmonji Temple, located in southern Tokyo, is in its final stages. Approximately 120,000 roofing tiles are being replaced. With a history stretching back more than 700 years, Honmonji Temple serves as the mausoleum of its founder, Saint Nichiren. Unfortunately, bombing in 1945 destroyed most of the temple's structures, though the graceful form of the main hall was rebuilt in 1964. And now, 41 years later, an extensive renovation is being undertaken to replace the cracked and displaced tiles that have become noticeable on the roof.

The original, ornamental demon-faced tiles (left) were redesigned for the new roof (right).

The central roof rises to approximately 30 meters (98 feet), has an area of approximately 2,300 square meters (24,600 square feet), and at its steepest point has an angle of 43 degrees from the ground. The work required use of lifelines by tile workers and the installation of safety nets. One of the most evident aspects of craftsmanship is the slope of the roof, determined by the craftsman's sense, refined by experience to create the proportions that appear most beautiful when viewing the building from a distance. Seen from far away, the roof's center appears to arch inward, drawing a gentle curve from its peak. The careful and painstaking work has proceeded steadily since April 2005, and is scheduled for completion in April this year. A wooden statue of Saint Nichiren (designated by the Japanese government as an important cultural asset) is also enshrined in the main hall. During renovation of the interior in 2002, Kajima installed an elevator that would immediately move the statue to a reinforced, fireproof room underground in the event of a fire or earthquake.

Above (from left): -- A monk writes a prayer commemorating construction of the roof. -- Interior of the hall where the statue of Saint Nichiren is enshrined. Below (from left): -- A festival being held at the main hall at Honmonji Temple -- Workers lay tile along the steep roof.

Shoboji Temple The main hall of Shoboji Temple, built in 1811 in Mizusawa, Iwate Prefecture, is known for having the largest thatched roof in Japan. An extensive renovation is being conducted to simultaneously replace the thatch, repair and replace damaged foundation stones, and repair decayed sections. The gambrel roof is 40 meters (130 feet) wide, 30 meters (98 feet) deep, and 21 meters (70 feet) high. The thickness of the thatch is approximately 120 centimeters (3.9 feet). Thatching requires 15,000 bales of rope-bound thatch, 150 centimeters (4.9 feet) long. The framework and trusses of the main hall are an intricate web of hundreds of components, constructed with traditional methods to form joints without nails or metal braces. This is the first major repair work in 190 years, and 40-year-old thatch was also replaced. The work is scheduled for completion in August this year.

Main hall of Shoboji Temple

Stone Walls of Sendai Castle Computer technology has been employed to restore and preserve the stone walls of Sendai Castle (Miyagi Prefecture), constructed in the late 1600s. The walls began curving outward in the 1960s, and experts had indicated there was a possibility that they might collapse. The walls, 190 meters (625 feet) long and 5 to 18 meters (16 to 60 feet) high, are composed of more than 10,000 individual stones. Master stonemasons were able to relay the stones in their original positions, based on information obtained using 3D imaging technology in a perfect example of a collaboration between cutting-edge technology and traditional craftsmanship.

Stone walls of Sendai Castle

Holy Resurrection Cathedral (Nikolai-do) Renovation of Tokyo's Nikolai-do-- the cathedral of the Orthodox Church in Japan, built in 1891--was carried out by employing the magnetic flux inspection method to determine the position of steel beams and inspect their coverings, the use of radar, and the Rebar Corrosion Diagnostic System, which allows for determination of high salt content. For the restoration of plaster surfaces, Kajima employed original technologies that beautify the surface through application of a cleansing pack to remove grime, similar to a facial mask.

Nikolai-do, first built in 1891

Rebuilding Historical Landmarks Shimbashi Railway Station A historical building that was once lost is being brought back. The original Shimbashi Railway Station in Tokyo was destroyed in the Great Kanto Earthquake of 1923, and was recently rebuilt in its original location among the high-rise buildings that now occupy much of the Shiodome area. Computer technology was employed to reconstruct the building, based on two period photographs taken at the time of construction in 1872, along with remains uncovered during surveys of historical sites. The Shimbashi Railway Station was the first railway station in Japan. Kakegawa Castle Kajima reconstructed Kakegawa Castle, built originally in 1596 in Shizuoka Prefecture, but destroyed in a major earthquake in 1854. The main tower was faithfully restored to original specifications, based on the remains of other towers and period illustrations. It is the only castle in Japan to have been rebuilt as a completely wooden structure.

Vol. 36 Spring 2006 Passing on Our Heritage:Technology Preserving Cultural Assets Kajima around the World

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