Causeway

Wendover Cut-off construction

Uruma Kaichu Doro

Great Salt Lake by Sentinel-2

I-195 Miami eastbound

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Causeway refers to a type of road or railway constructed across a body of water or wetland. It is designed to provide a direct route for transportation over areas that are otherwise difficult to traverse. Causeways can be built using earth, stone, or other materials, and they often include bridges or viaducts to allow water flow and navigation. The concept of causeways has been utilized since ancient times, serving both practical transportation needs and ceremonial or strategic purposes.

History

The history of causeways dates back to ancient civilizations, where they were used to connect islands to the mainland or to cross bodies of water and wetlands. One of the most famous ancient causeways is the Causeway of the Pharaohs in Egypt, which connected ancient temples on the mainland to the temple complexes on Philae Island. In the Americas, the Aztecs built extensive causeway networks to connect their capital, Tenochtitlán, situated on an island in Lake Texcoco, to the mainland.

Construction

The construction of a causeway involves the placement of fill material, such as earth, rock, or concrete, to create a raised roadbed. In areas where the causeway must allow water flow or navigation, bridges or culverts are incorporated into the design. Modern causeways may also include features to mitigate environmental impacts, such as providing passages for aquatic life.

Types

There are several types of causeways, including:

• Land causeways: Built over wetlands or marshy areas to provide road or railway access.
• Water causeways: Constructed across bodies of water, these can be simple embankments or more complex structures with bridges.
• Tidal causeways: These are submerged at high tide and emerge at low tide, connecting the mainland to tidal islands.

Examples

Notable examples of causeways include:

• The King Fahd Causeway, which connects Saudi Arabia and Bahrain across the Persian Gulf.
• The Adam's Bridge (also known as Rama's Bridge), a chain of limestone shoals between Pamban Island, also known as Rameswaram Island, off the southeastern coast of Tamil Nadu, India, and Mannar Island, off the northwestern coast of Sri Lanka.
• The Lake Pontchartrain Causeway in Louisiana, USA, one of the longest continuous bridges over water in the world.

Environmental Impact

While causeways provide essential transportation links, they can also have significant environmental impacts. By altering water flow and sediment distribution, causeways can affect marine and wetland ecosystems. Efforts to mitigate these impacts include designing causeways to include wildlife crossings or culverts to maintain water flow and reduce habitat fragmentation.

See Also

• Bridge
• Viaduct
• Embankment