TEMPO.CO, Jakarta - An underwater tunnel or toll road is a highway below sea level that provides access for vehicles from one land to another. The underwater toll road has a long history, starting from a road that "merely" crossed a river of 0.4 kilometers wide to an underwater toll road with a length of more than 50 kilometers.
Undersea toll roads can now be found in several developed countries. Indonesia plans to build an underwater toll road in the new capital city of Nusantara, or IKN. In the future, the underwater toll road will connect the Balikpapan-Samarinda toll road with the new capital.
Here is the list of countries that own an underwater toll road:
1. China
In January 2022, China officially inaugurated another of its underwater toll roads measuring 10.79 kilometers. The toll road is called Taihu Tunnel as it spans in the middle of Lake Taihu in Jiangsu Province. Previously, China built an undersea tunnel in Xiamen, Fujian Province 2005–2010, called the Xiang’an Tunnel of 8.69 kilometers long.
Another one connects Hong Kong, Zhuhai, and Macau which is a combination of bridge and underwater tunnel. The length of the underwater road is 6.7 kilometers from the overall total of 55 kilometers long.
2. Britain
Britain has the oldest underwater tunnels, namely the Blackwall Tunnel, the Queensway Tunnel, and the Channel Tunnel.
The Blackwall has two separated lines with lengths of 1.35 kilometers and 1.17 kilometers respectively. The roads lie under the Thames River in the Blackwall and Greenwich areas since 1897.
The Queensway Tunnel was built in 1925–1934 under the Mersey River between Liverpool and Birkenhead. The road also known as the “Birkenhead Tunnel” or the “Old Tunnel” measures 3.24 kilometers long.
Meanwhile, The Channel Tunnel lies from Folkestone, the U.K. to Calais, France with the underwater line at 37.9 kilometers from the total of 50.4 kilometers. The road was built in 1988–1994.
3. Japan
Japan has at least two underwater roads, which are the Kanmon Tunnel and the Tokyo Bay Aqua-Line. The Kanmon Tunnel connects the islands of Honshu and Kyushu in the cities of Shimonoseki and Kitakyushu. The length is 3.46 kilometers which is equipped with sidewalks for pedestrians. The tunnel was built from 1937 to 1958.
Meanwhile, the Tokyo Bay Aqua-Line is a combination of a bridge and an undersea tunnel. It is located under Tokyo Bay with a length of 9.6 kilometers from a total of 23.7 kilometers.
4. Norwegia
Citing New Civil Engineer, Norway has deeper underwater roads than other countries. The tunnels connect small islands on the edge of the country.
There is the Ryfast Tunnel that connects Stavanger and Ryfylke, it spans 14.3 kilometers at a depth of 293 meters. Then the Eiksund Tunnel with 7.7 kilometers long and 287 meters deep.
The Hitra Tunnel is 5.6 kilometers long and 264 meters deep. Several other underwater tunnels include the Bomlafjord Tunnel, North Cape Tunnel, Flekkeroy Tunnel, and Fardo Tunnel.
5. South Korea
South Korea has an underwater Boryeong Tunnel along 6.9 kilometers that connects Boryeong with Wonsan Island. There is also the combination of a bridge and an undersea tunnel between Busan and Geoje. The undersea tunnel lies along 3.2 kilometers.
Lastly, there is Tongyeong Tunnel which was initially opened specifically for motorcycles in 1932. But the 483-meter-long road is now only used for pedestrians heading to Mireukdo Island.
6. The United States
Undersea tunnels in the U.S. are Lincoln Tunnel and Holland Tunnel. Both tunnels connect New York and New Jersey which are separated by the Hudson River. Each length is around 2.4 kilometers and 2.6 kilometers respectively.
In addition, there are Detroit-Windsor Tunnel that connects Detroit in the U.S. and Windsor in Canada. The length reaches 1.57 kilometers.
7. Turkey
Turkey has an underwater tunnel that connects the Asian and European continents. It lies along the Bosphorus Strait, Istanbul measuring 5.4 kilometers.
NIA HEPPY | SYAHDI MUHARRAM