Entrance to Tokyo Bay AquaLine, Tokyo, Japan
The Tokyo Bay Aqua-Line is a bridge-tunnel-combination across Tokyo Bay in Japan. It connects the city of Kawasaki in Kanagawa Prefecture with the city of Kisarazu in Chiba Prefecture. With an overall length of 14 km, it includes a 4.4 km bridge and 9.6 km tunnel underneath the bay - which is the longest underwater tunnel for cars in the world.
At the bridge-tunnel crossover point, there is an artificial island called the "Umi-hotaru (海ほたる, engl. sea firefly)" with a rest area as well as the usual restaurants, shops and amusement facilities. The characteristic wind tower Kaze no tō (風の塔) in the middle of the tunnel is used to pump air into the tunnel.
The road carries National Route 409 across the bay. It opened on December 18, 1997 after 31 years of construction at a cost of 1.44 trillion yen (11.2 billion USD at the time of opening). With the Tokyo Wan Aqualine the drive from the most important industrial regions Chiba and Kanagawa is reduced to 15 minutes. Before it was opened one had to drive a 100km long way along the Tokyo Bay which automatically leads through the center of Tokyo. One aim during the planning of the Aqualine was to reduce the traffic through the center of Tokyo, but as the highway toll is still quite high at 3,700 Yen, this effect doesn't take place as strong as expected.
The Gotthard Base Tunnel (GBT) is a railway tunnel under construction in Switzerland. With a planned length of 57 km (35 miles) and a total of 153.5 km (95 miles) of tunnels, shafts and passages planned, it will be the longest railway tunnel in the world upon completion, ahead of the current record holder, the Seikan Tunnel. The project is designed to feature two separate tunnels containing one track each. The tunnel is part of the Swiss AlpTransit project, also known as New Railway Link through the Alps NRLA which also includes the Lötschberg Base Tunnel between the cantons of Berne and Valais. Like the Lötschberg tunnel, it is intended to bypass winding mountain routes and establish a direct route suitable for high speed rail and heavy freight trains. On completion it is expected to decrease the current 3.5 hours travel time from Zürich to Milan by one hour. The two portals will be near the villages of Erstfeld, Canton Uri and Bodio, Canton Ticino. Completion has been projected for 2015 but due to delays the tunnel may only be completed as late as 2017. Nearby are two more St. Gotthard Tunnels: the 1881 railway tunnel and the 1980 road tunnel.
The Sydney Harbour Tunnel is a tunnel in Sydney, Australia. It was completed in August 1992 to provide a second vehicular crossing of Sydney Harbour to alleviate congestion on the Sydney Harbour Bridge. The tunnel is made up of three sections: twin 900-metre land tunnels on the north shore, twin 400-metre land tunnels on the south shore and a 960-metre immersed tube (IMT) structure. It joins the Warringah Freeway at North Sydney and the Cahill Expressway at the entrance to the Domain Tunnel. The tunnel falls about 55 metres from the northern entrance and about 35 metres from the southern entrance to its deepest point, 20 metres below sea-level.
The IMT structure consists of eight precast concrete units. The units were constructed over 100 kilometres away in a dry dock at Port Kembla and then towed to Sydney Harbour. A trench was dredged prior to the arrival of the IMTs and then the IMTs were lowered into the trench by a system of pontoons and control towers. After the IMTs were in place the trenches were backfilled and then a rock armour was placed over the top to protect the units against marine hazards, such as anchors or sinking vessels.