Everything about Causeway totally explained
In modern usage, a
causeway is a road or railway elevated by a bank, usually across a broad
body of water or
wetland. A transport corridor that's carried instead on a series of arches, perhaps approaching a bridge, is a
viaduct. In the U.S. a short stretch of viaduct is called an
overpass. The distinction between the terms
causeway and
viaduct becomes blurred when flood-relief
culverts are incorporated, though generally a causeway refers to a roadway supported mostly by earth or stone, while a bridge supports a roadway between piers (which may be embedded in embankments). Some low causeways across shore waters become inaccessible when covered at high
tide.
Etymology
When first used, the word appeared in a form such as “causey way” making clear its derivation from the earlier form “causey”. This word seems to have come from the same source by two different routes. It derives ultimately, from the Latin for heel,
calx and as near certainly as may be, comes from the trampling technique for consolidating earthworks. In antiquity, the construction was trodden down, one layer at a time, often by
slaves or a flock of
sheep. Today, a machine does the job. The same technique would have been used for road embankments, raised river banks, sea banks and
fortification earthworks. (The layers, though not the trampling action, can be seen in the
Bayeux Tapestry: Building Hastings Castle.)
The second derivation route is simply the hard, trodden surface of a path. The name by this route came to be applied to a firmly-surfaced road. It is now little-used except in dialect and in the names of roads which were originally notable for their solidly-made surface.
The word is comparable in both meanings with the
French chaussée, from a form of which it reached
English by way of
Norman French. The French adjective,
chaussée, carries the meaning of having been given a hardened surface, and is used to mean either paved or shod. As a noun
chaussée is used on the one hand for a metalled carriageway, and on the other for an embankment with or without a road. Other languages have a noun with similar dual meaning. In
Welsh, it's
sarn. The Welsh is relevant here, as it also has a verb,
sarnu, meaning to trample. The trampling and ramming technique for consolidating earthworks was used in fortifications and there's a comparable, outmoded form of wall construction technique, used in such work and known as pisé, a word derived not from trampling but from ramming or tamping.
Engineering
The modern embankment may be constructed within a
cofferdam: two
parallel steel sheet
pile or
concrete retaining walls,
anchored to each other with steel cables or rods. This construction may also serve as a
dyke that keeps two bodies of water apart, such as bodies with a different water level on each side, or with
salt water on one side and
fresh water on the other. This may also be the primary purpose of a structure, the road providing a hardened crest for the dike, slowing erosion in the event of an overflow. It also provides access for maintenance as well perhaps, as a public service.
Examples
Notable causeways include those that connect
Singapore and
Malaysia (the
Johor-Singapore Causeway),
Bahrain and
Saudi Arabia (25-km long
King Fahd Causeway) and
Venice to the mainland, all of which carry roadways and railways. In the
Netherlands there are a number of prominent dykes which double as causeways, including the
Afsluitdijk,
Brouwersdam, and
Markerwaarddijk. In
Louisiana, two very long bridges, called the
Lake Pontchartrain Causeway, stretch across
Lake Pontchartrain for almost 38 km, making them the world's longest bridges (if total length is considered instead of span length). They are also the oldest causeways on the Gulf Coast that have never been put out of commission for an extended period of time following a Hurricane. In the Republic of
Panama a causeway connects the islands of Perico, Flamenco, and Naos to
Panama City on the mainland. It also serves as a breakwater for ships entering the
Panama Canal. The oldest engineered road yet discovered is the
Sweet Track in
England, dating from the
3800s BC.
Causeways are also common in
Florida, where low bridges may connect several man-made
islands, often with a much higher bridge (or part of a single bridge) in the middle so that taller
boats may pass underneath safely. Causeways are most often used to connect the
barrier islands with the
mainland.
The
Churchill Barriers in
Orkney are of the most notable sets of causeways in Europe. Constructed in waters up to 18 metres deep, the four barriers link five islands on the eastern side of the natural harbour at
Scapa Flow. They were built during
World War II as military defences for the harbour, on the orders of
Winston Churchill.
Precautions
Causeways affect currents and may therefore be involved in beach
erosion or changed deposition patterns. This, for instance, has been a problem at the
Hindenburgdamm in northern Germany. Causeways are often a problem with an approaching
hurricane or strong
tropical storm, because the high
winds and
waves make them dangerous. Along with
traffic jams, this is a major reason for the early
emergency evacuation of
island residents during a weather emergency.
Further Information
Get more info on 'Causeway'.
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