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Civil Engineering Business

Civil engineering is indispensable for society to function. Yet, people seldom notice the infrastructure that supports their everyday lives—largely because so much of it is unseen. For example, the utility ducts constructed by Kajima carry many kinds of utility lines underground, including those for gas, electricity, water and sewage.

Kajima's history began with building railways, after which the company expanded its business to the construction of infrastructure including dams, bridges and roads. Kajima has also accumulated a wide range of technology and expertise in its civil engineering business in areas such as power facilities, transportation networks and the aforementioned utility ducts. Indeed, the company's achievements in civil engineering led the way for the economic development of Japan. Kajima has also been active internationally, having undertaken major projects in countries around the world.

Shin-Sugita Common Utility Duct

Photo: Shin-Sugita Common Utility Duct

Figure: Shin-Sugita Common Utility Duct

Many structures that support our daily life remain hidden from casual observation even after they have been completed. A common utility duct, for example, is an underground tunnel that carries many different kinds of utility lines, including gas, electricity, water, sewage, and other types of infrastructure that are indispensable to our daily lives. Once a common utility duct has been constructed, it is no longer necessary to excavate the street every time something must be replaced, and the ability to visually inspect water lines and the like greatly simplifies the task of maintenance. Furthermore, if an earthquake or other major disaster occurs, damage can be quickly pinpointed and repaired. Where common utility ducts are in place, a city is much better prepared to deal with emergencies.

To make local infrastructure more resistant to disasters, a 220-kilometer common utility duct is being planned for the Yokohama-Kawasaki area in Kanagawa Prefecture. The Ministry of Land, Infrastructure, Transport and Tourism has awarded a contract for the project, and work is currently in progress in the Shin-Sugita district, located along the coast of Tokyo Bay in Yokohama where the duct is being constructed directly beneath Capital Expressway Route 357. A Kajima joint venture is responsible for a 3.3-kilometer segment of the construction.

The Kajima joint venture proposed tunneling deeper beneath the surface than what had been called for in the basic design, because the shallower land is soft and spongy, while tunneling in a deeper and more stable stratum would minimize the impact of the project upon the Capital Expressway Coastal Viaduct on the surface and allow for a more earthquake-resistant structure. This proposal received very positive reviews, and the company was awarded a design-build contract.

In order to build a stable lifeline that has a long Project Workflow service life and is highly resistant to disaster, the duct and its ancillary elements have all been designed to last 75 years, which is unprecedented in the industry. The Kajima joint venture is pouring every bit of its know-how into the design and construction of the common utility duct that will provide area residents with safety and peace of mind in the future.

Map: Shin-Sugita Common Utility Duct

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Project Workflow

01 Starting shaft is constructed

A vertical shaft is first dug where the shield tunneling machine will start excavating.

Photo: Capital Expressway Coastal Viaduct

Height restrictions and extraordinary caution is required for the construction conducted directly beneath the Capital Expressway Coastal Viaduct.

02 The Shield tunneling machine is lowered into place

The shield tunneling machine is lowered down to the bottom of the shaft, where tunneling will commence.

Photo: "Hammer Shield 636"

After a public contest to solicit names for the shield tunneling machine, it was named the "Hammer Shield 636."

03 Tunnel is bored

The shield tunneling machine digs its way forward through the earth, installing tunnel wall segments as it goes. The Hammer Shield 636 also features an automatic segment conveyor system.

Photo: Inside in Tunnel

04 Tunnel interior is built

The central dividing wall and floors are constructed first. Two sewer lines are being installed on the upper level left side as seen from the leading edge of the tunnel. A water line is being installed on the next level down.

Photo: Sewerage

05 Service shafts are constructed

Shafts will be built through 2011 to provide ventilation in the tunnels and repair and servicing ducts that branch to the surface.

Photo: Service Shaft

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