Seikan Tunnel Trivia

Vertical shaft

Originally used as an elevator shaft for hauling workers, materials and machinery. Now it is used as a way to ventilate smoke.
Main shaft

This is a railway tunnel 7.85 meters high, 9.7 meters wide, and is big enough for a 3 story building to fit inside.
Pilot drift shaft

This is the front most part of the dig in the tunnel. It supported the digging of the main shaft and construction shaft by carefully researching and testing the nature of the soil and the way the sea water seeped through, and then contemplating development and way of excavation.
Now it is used for drainage, and ventilation.
Construction shaft

It is built 30meters to the side of the main shaft. Its purpose was to always be ahead of the main shaft to make connecting guide paths, and to hasten the pace of digging by increasing the face. It also acted as a means for transporting materials, machinery and to carry out the muck.
Now it is used as a alternative passageway which is used by trucks and cars.
Inclined shaft

There are two main inclined shafts, one in Yoshioka and the other in Tappi. It is inclined at a grade of 14 degrees toward the seabed, and was used to conduct geological surveys, to carry workers, materials, machinery and muck (rocks and mud left over from the dig).
Now it is used as a passageway to blast air for ventilation. It is also used as an entrance for maintenance and there is a cable car for carrying materials.

Standard cross section of the sea bed section (unit: meters)
In the seabed of the Seikan Tunnel there are three tunnels; the pilot drift shaft, the construction shaft and the main shaft.

Tunnel cross section
(unit: meters)
Design description of the Seikan Tunnel
Beginning point: Aomori Prefecture Higashi Tsugaru-gun Imabetsu cho Hamana
End point: Hokkaido Kamiiso-gun Shiriuchi-cho Yunosato
Tunnel Extension 53.85km
Sea bed section: 23.30km
Surface section: 30.55km
Tunnel design standards Minimum curve radius: 6.500m
Maximum grade: 12/1000
Minimum overburden (under seabed): 100m
Maximum sea depth: 140m
Tunnel cross section: Double Track Shinkansen Type
Track Structure Triple Slab Track
(Capable of running Shinkansens along with regular trains in the future.)

Tunnel Extension 53.85km (equal to the length of one lap of the Tokyo Yamanote line)
in which 23.30km is under the sea bed.
Super Long Rail Extension 52.57km
Amount of cement used Approximately 85,000 tons, 850 times the height of Mt. Fuji if you piled up all of the cement bags.
Infusion of liquid glass and cement composition into the electoral turf. 847,000 square meters
(1.6 times the capacity of the Kasumigaseki building)
Amount of steel materials Approximately 17thousand tons.
(Equal the amount needed to build 57 Tokyo Towers)
Amount of soil dug Approximately 630 thousand square meters.
(12.1 times the capacity of the Kasumigaseki building)
Amount of explosives used Approximately 2,900 tons
Amount of construction workers Approx. 14 million
Construction period Approx. 24 years
Undersea station position Yoshioka Undersea Station: 149.5m undersea
Tappi Undersea Station: 135.0m undersea
Total construction cost Approx. 6,90billion yen

You will hear the sound of water as if you were in a forest.

The amount of sea water soaking the walls of the tunnel that is drained is about 20 tons a minute.
The sound of water that makes you feel as if you were in a forest comes from this sound from the drain.
Inspection within the main shaft is done by a two passenger patrol car.

A two passenger diereses engine patrol car runs in the aisle between the two tracks.
The environment underground is maintained with temperatures at 20 degrees and humidity set at 80-90%.

Throughout the year this temperature of 20 degrees and 80-90% humidity is maintained.
Tunnel inspection is done by bicycle and truck.

In order to cut down on exhaust inside of the tunnel, we use diesel engine trucks.
The fastest way from the ground to the inside of the tunnel is the cable car that travels 150 meters per minute.

The cable car that travels 150 minutes per minute will take 15 passengers to a fixed point in 5 minutes, and to the basement in another 3 minutes.
Just for your information, the stairs in the Yoshioka inclined shaft are 2,102 steps, and 2,247 steps in the Tappi shaft.
There is a pleasant breeze that blows inside the tunnel.

By sending 3,800 square meters of wind from both the Yoshioka inclined shaft and the Tappi inclined shaft every minute, a one-meter wind continually blows toward the exits allowing for continual ventilation.

The setoff base, the largest space inside the tunnel.

16 meters wide, 10 meters high and 91 meters long, this is the largest maintenance base inside of the tunnel.
Surveying technology that won the world’s highest praise.

The survey style that incorporates a laser was most effective in the penetrating 23.3km into the seabed of the Seikan tunnel.
Different technology was used according to the type of electoral turf that was being dug, and in horizontal boring, succeeded in boring 2,150 meters, the longest in the world. This surprised the world.