In general, two kinds of structures are used to provide a way across a river, canal, sea, or other obstacle: bridge structures that pass over the obstacle, and tunnel structures that pass below the obstacle. Although the construction of both bridges and tunnels can be traced back over thousands of years, bridge–tunnel combinations that use an island as a sea-crossing fixed link (SCFL) have only been built over the past 82 years. The first such combination was probably the 6.4 km long San Francisco–Oakland Bay Bridge in the United States, which was completed in 1936. The most recently constructed SCFL combining a bridge, tunnel, and island is the Hong Kong–Zhuhai–Macao (HZM) Bridge, which opened for traffic on October 24, 2018 with the longest SCFL combination in the world, at a total length of 29.6 km.
展开▼