|
| President Mitsuyoshi Nakamura (standing fourth from the right) presses the machine startup switch
|
On December 22, 2008, Kajima held a ceremony at the departure vertical shaft yard in Shinagawa Ward, Tokyo, to mark the launch of the shield tunneling machine for the Central Circular Shinagawa Route of the Tokyo Metropolitan Expressway.
As the final stretch of the Central Circular Route (which will reach about 47 kilometers when completed), the Shinagawa Route will connect Shibuya to Shinagawa over a total of about 9.4 kilometers, including an 8.4-kilometer underground tunnel which will be constructed using environmentally responsible technology.
|
| Kajima’s relay bit method enables the cutter bits of shield tunneling machines, which can be worn away by excavation, to be exchanged at any time with no additional work or equipment. Bits can be exchanged from inside the shield machine, which has working space at atmospheric pressure.
|
A Kajima joint venture is constructing the tunnel using the mud-pressure method and a large-diameter shield machine that is 12.55 meters across. The shield machine will excavate the entire 8.4 kilometers—the world’s longest distance on record for a single shield machine—at an average rate of 300 meters per month. A large-scale cutter bit is being used to eliminate the need to change the bit during excavation. However, in the event the cutter bit must be changed, it can be switched at any time using the relay bit method. The construction is scheduled for completion in February 2013.
The stretch of the Central Circular Route connecting Shibuya to Shinjuku is scheduled to open by the spring of 2010. When the Shinagawa Route is complete, the entire Central Circular Route will be ready for traffic, significantly reducing traffic congestion on the Metropolitan Expressway.
|
