|
Outline
The Toei Oedo Line forms a 41-km underground loop around metropolitan
Tokyo. Following a construction period of 14 years, the line opened
to passengers in December 2000. The new subway reinforced the cityfs
complex public transport network, bringing transport convenience
to many localities. In particular, the subway now links the northwest
and older downtown areas with the major sub-centre of Shinjuku,
where the Tokyo Metropolitan Government and major high-rise business
and commercial precincts are located. The opening of the line has
invigorated the economies of numerous districts located along its
route.
|
|
Technical
Features
Having to cope with an already densely developed underground environment,
the subway is one of the deepest in the world, ranging between 15
m and 48 m below ground. To reduce construction cost, the outer diameter
of the tunnel was set at only 5.3 m, some 2 m smaller than previous
subway tunnels. The trains are driven by linear induction motor and
are able to handle a particularly tight minimum curve radius of 102
m.
Where soil conditions were favorable, the tunnel lining used boltless
construction. Lining segments were fixed to the tunnel wall with
dowel, and keyed joints were used between adjacent lining segments,
the first time this method of construction had been used for a railway
tunnel in Japan.
|
|
|
Role of
NCC in tunnel construction
Although the project was constructed using the design-build approach,
NCC was responsible for segment lining design and construction supervision
of almost half of the tunnel sections that used boltless segment
joints. In addition, because of its technical experience in the design
of shield tunnels, NCC was given responsibility for providing the
overall design concept for these sections.
|
|
|
Segmental lining of
the Toei Oedo subway line tunnel showing dowel
insertion points near the centre of the pre-cast
concrete segments. |
|
|
|
|
|