BRIDGES AND TUNNELS

Copyright © 1994 EJRCF. All rights reserved.

Bridges and tunnels linking the Japanese Archipelago

The four major islands of Japan became united in 1988, when theKojima-Sakaide Route of the Honshu-Shikoku Bridges and the SeikanTunnel between Honshu and Shikoku opened to traffic. These are thetunnels and bridges carrying the railways and roads between the fourislands.

Honshu-Shikoku Bridges

The Honshu-Shikoku Bridges comprise three routes. Both the most-easterlyKobe-Naruto route and the most-westerly Onomichi-Imabari route are designedonly for road traffic, but the Kojima-Sakaide route in the middle, a long chain ofgigantic two-level bridges and viaducts opened in 1988, is for both rail and roadtraffic.

� The total length of the double-deckbridges and viaducts of the Kojima-Sakaide route is 13.1 km, and the largest bridge is the Minami Bisan-Seto Bridge, asuspension bridge with a centre span of 1.1 km.

� The Akashi Kaikyo Bridge of the Kobe-Naruto route, due to open in 1998 with a six-lane motorway, will be by far the world'slongest suspension bridge with a centrespan of 1.99 km.

Courtesy: Honshu-Shikoku Bridge Authority

Courtesy: Geographical Survey Institute

Courtesy: Honshu-Shikoku Bridge Authority

(continued on P.43)

Courtesy: JR Shikoku

� Although only a double-track narrow-gauge railway is running at the moment, the structure isdesigned to carry another double track for a standard-gauge (shinkansen) to be built in the future.

BRIDGES AND TUNNELS

Copyright © 1994 EJRCF. All rights reserved. Japan Railway & Transport Review / June 1994 43

The Kanmon Strait between Honshuand Kyushu is a narrow and dangerouspassage with fast tidal currents throughwhich many merchant vessels sail.Train ferries used to cross the strait, butwartime Japan needed a safer means ofcarrying people and goods, and a 3.6-km single-track railway tunnel was com-pleted in 1942 as the first fixed link.

Another single-track tunnel (3.6 km) wascompleted in 1944. After the war, a two-lane road tunnel (3.46 km) was com-pleted in 1958. The third link is a sus-pension bridge completed in 1973 with acentre span of 712 metres, carrying asix-lane motorway. Rapid economicgrowth brought the extension of theshinkansen network to Kyushu, and thedouble-track Shin-Kanmon Tunnel (18.7km) was completed in 1975.

Courtesy: Geographical Survey Institute

Kanmon Bridge and Tunnels

� The Kanmon Bridge carrying a six-lane motorway.

� Four fixed links crossing the Kanmon Strait: (left to right) the Kanmon Railway Tunnel, the KanmonMotorway Bridge, the Kanmon Road Tunnel and the Shin-Kanmon Tunnel for shinkansen.

Courtesy: Japan Highway Public Corporation

� The Kanmon Railway Tunnel: The underseapart comprises two separate single-tracktunnels.

Courtesy: JR Kyushu

� A Series 300 Nozomi super-express trainleaving the Shin-Kanmon Tunnel.

Courtesy: JR West

BRIDGES AND TUNNELS

Copyright © 1994 EJRCF. All rights reserved.44 Japan Railway & Transport Review / June 1994

Seikan Tunnel

The island of Hokkaido was Japan'sfrontier for a long time. People wentthere to open up new land and theisland's rich natural resources werebrought to the main island by sea. TheTsugaru Strait between Hokkaido andHonshu is a wide and stormy interna-tional waterway through which manyships, including naval vessels ofJapan's neighbours, pass frequently.In 1954, the Toya-Maru, a train ferrysailing between Aomori and Hakodate,was hit by a severe typhoon and sankwith 1,314 passengers (of whom only159 survived). The disaster promptedthoughts of constructing a railway tun-nel under the strait, and a series of seri-ous studies were started.

The construction work started officiallyin 1964, and the tunnel was finallyopened in 1988. The engineeringworks were extremely difficult and ex-pensive because of bad geological con-ditions. The total length of the tunnel is53.85 km including the 23.35 km underthe sea. The main tunnel is designed tocarry a double-track shinkansen line infuture, although only narrow-gaugetrains are running at present. The twoundersea stations are mainly for emer-gency use, but tourists can enjoy ashort guided visit.

� The Toya-Maru disaster (26 September 1954)prompted thoughts of building an underseatunnel.

Courtesy: Asahi Shimbun

Courtesy: Geographical Survey Institute

BRIDGES AND TUNNELS

Copyright © 1994 EJRCF. All rights reserved. Japan Railway & Transport Review / June 1994 45

� The 23.35km undersea part comprises three bores: a double-trackrailway tunnel, a parallel service tunnel, and a pilot tunnel nowserving as a drainage tunnel.

� In future, the main tunnel will be used forshinkansen traffic, too.

� A train arriving at Tappi-Kaitei station at theHonshu undersea side of the tunnel.

Courtesy: JR Hokkaido

� Huga halls behind the undersea stationplatforms are currently used for touristexhibition. The halls will be used asshinkansen track maintenance depots infuture.

Courtesy: JR Hokkaido