Intercontinental and transoceanic fixed links

South East Asia
Mainland Peninsula Malaysia is connected to Penang Island by two road bridges: Penang Bridge and Penang Second Bridge. To the south, it is linked to Singapore Island across the Straits of Johor by the Johor–Singapore Causeway and the Malaysia–Singapore Second Link; the former also carries Malaysia's West Coast Line to the island.

There are also plans to link Java, the most populated state in Indonesia towards the Sumatra on the Sunda Strait Bridge, the Malaysia and Indonesia along the Malacca Strait Bridge and the Indonesia and Singapore along the Singapore Strait crossing.

English Channel
There is no highway connection between Great Britain and the European mainland; only a rail connection, the Channel tunnel.

A cross channel rail tunnel was first proposed in 1802 and construction actually started in 1881 before being abandoned. Roll-on Roll-off ferry services provided links across the channel for vehicles.

A road tunnel was proposed in 1979, but not considered viable. Construction of the Channel Tunnel started in 1988 and the tunnel opened in 1994. Automobiles and lorries/transport trucks are loaded onto the Eurotunnel Shuttle's enclosed railway cars (similar to auto rack/motorail railway cars) for the trip through the tunnel, however. A service tunnel runs the entire length of the crossing, but is closed to general use and used only during emergencies and for maintenance.

Trans-Global Highway
The Trans-Global Highway is a range of highway systems proposed by futurist Frank X. Didik that would link all six of the inhabited continents. People could drive cars from Australia to California via Russia and Alaska. People from New York could drive to London via Greenland. The highway would network new and existing bridges and tunnels, improving ground transportation and potentially providing a conduit for utility pipelines. However, in the Discovery Channel's "Extreme Engineering", it was noted that the Chukotka area is mostly roadless and uninhabited, and infrastructure would need to be developed completely from scratch. Chukotka is on the Eurasian side of the Bering Strait, where the highway would connect to North America via tunnels.

Transatlantic highway
The transatlantic tunnel is a theoretical tunnel that would span the Atlantic Ocean between North America and Europe possibly for the mass transit. Some proposals envision the advanced trains reaching speeds of 500 to 8,000 km/h. The tunnel envision between the United States and United Kingdom - or more specifically between North America and London.

Advantages compared to air travel could be increased speed and the use of electricity instead of oil-based fuel, considering after the peak oil.

The main barriers of constructing such a tunnel could be cost, with estimates of between $88 billion and $175 billion, as well as the limits of current material science. Existing major tunnels, such as Channel Tunnel, Seikan Tunnel and Gotthard Base Tunnel, despite using less expensive technology than any project for the transatlantic tunnel, struggle financially.