A bridge is a structure built to span physical obstacles without
closing the way underneath such as a body of water, valley, or road,
for the purpose of providing passage over the obstacle. There are many
different designs that each serve a particular purpose and apply to
different situations. Designs of bridges vary depending on the
function of the bridge, the nature of the terrain where the bridge is
constructed and anchored, the material used to make it, and the funds
available to build it.
3 Types of bridges
3.1 Structure type
3.2 Fixed or movable bridges
3.3 Double-decked bridges
3.5 Three-way bridges
Bridge types by use
Bridge types by material
8 Visual index
9 See also
11 Further reading
12 External links
Akashi Kaikyō Bridge
Akashi Kaikyō Bridge in Japan, currently the world's longest
Siosepol bridge over Zayandeh River is an example of Safavid
dynasty (1502–1722) bridge design. Esfahan, Iran
Oxford English Dictionary
Oxford English Dictionary traces the origin of the word bridge to
Old English word brycg, of the same meaning. The word can be
traced directly back to Proto-Indo-European *bʰrēw-. The word for
the card game of the same name has a different origin.
Arkadiko Bridge in
Greece (13th century BC), one of the oldest
arch bridges in existence
Bridges in Amsterdam, Netherlands
Arkadiko Bridge is one of four Mycenaean corbel arch bridges part
of a former network of roads, designed to accommodate chariots,
between the fort of Tiryns and town of Epidauros in the Peloponnese,
in southern Greece. Dating to the Greek
Bronze Age (13th century BC),
it is one of the oldest arch bridges still in existence and use.
Several intact arched stone bridges from the Hellenistic era can be
found in the Peloponnese.
The greatest bridge builders of antiquity were the ancient Romans.
The Romans built arch bridges and aqueducts that could stand in
conditions that would damage or destroy earlier designs. Some stand
today. An example is the Alcántara Bridge, built over the river
Tagus, in Spain. The Romans also used cement, which reduced the
variation of strength found in natural stone. One type of cement,
called pozzolana, consisted of water, lime, sand, and volcanic rock.
Brick and mortar bridges were built after the Roman era, as the
technology for cement was lost (then later rediscovered).
In India, the
Arthashastra treatise by
Kautilya mentions the
construction of dams and bridges. A
Mauryan bridge near
surveyed by James Princep. The bridge was swept away during a
flood, and later repaired by Puspagupta, the chief architect of
emperor Chandragupta I. The use of stronger bridges using plaited
bamboo and iron chain was visible in India by about the 4th
century. A number of bridges, both for military and commercial
purposes, were constructed by the Mughal administration in India.
Although large Chinese bridges of wooden construction existed at the
time of the Warring States, the oldest surviving stone bridge in China
is the Zhaozhou Bridge, built from 595 to 605 AD during the Sui
Dynasty. This bridge is also historically significant as it is the
world's oldest open-spandrel stone segmental arch bridge. European
segmental arch bridges date back to at least the Alconétar Bridge
(approximately 2nd century AD), while the enormous Roman era Trajan's
Bridge (105 AD) featured open-spandrel segmental arches in wooden
Rope bridges, a simple type of suspension bridge, were used by the
Inca civilization in the
Andes mountains of South America, just prior
to European colonization in the 16th century.
During the 18th century there were many innovations in the design of
timber bridges by Hans Ulrich Grubenmann, Johannes Grubenmann, and
others. The first book on bridge engineering was written by Hubert
Gautier in 1716.
A major breakthrough in bridge technology came with the erection of
Bridge in Shropshire, England in 1779. It used cast iron for
the first time as arches to cross the river Severn.
Industrial Revolution in the 19th century, truss systems of
wrought iron were developed for larger bridges, but iron does not have
the tensile strength to support large loads. With the advent of steel,
which has a high tensile strength, much larger bridges were built,
many using the ideas of Gustave Eiffel.
In 1927 welding pioneer
Stefan Bryła designed the first welded road
bridge in the world, the
Maurzyce Bridge which was later built across
the river Słudwia at Maurzyce near Łowicz, Poland in 1929. In 1995,
Welding Society presented the Historic Welded Structure
Award for the bridge to Poland.
Eciton sp. forming a bridge
Before humans, ants have been making bridges using their own bodies to
allow others to cross.
Types of bridges
Bridges can be categorized in several different ways. Common
categories include the type of structural elements used, by what they
carry, whether they are fixed or movable, and by the materials used.
Bridges may be classified by how the forces of tension, compression,
bending, torsion and shear are distributed through their structure.
Most bridges will employ all of the principal forces to some degree,
but only a few will predominate. The separation of forces may be quite
clear. In a suspension or cable-stayed span, the elements in tension
are distinct in shape and placement. In other cases the forces may be
distributed among a large number of members, as in a truss.
Beam bridges are horizontal beams supported at each end by
substructure units and can be either simply supported when the beams
only connect across a single span, or continuous when the beams are
connected across two or more spans. When there are multiple spans, the
intermediate supports are known as piers. The earliest beam bridges
were simple logs that sat across streams and similar simple
structures. In modern times, beam bridges can range from small, wooden
beams to large, steel boxes. The vertical force on the bridge becomes
a shear and flexural load on the beam which is transferred down its
length to the substructures on either side They are typically made
of steel, concrete or wood. Girder bridges and Plate girder bridges,
usually made from steel, are types of Beam bridges. Box girder
bridges, made from steel, concrete, or both are also beam bridges.
Beam bridge spans rarely exceed 250 feet (76 m) long, as the
flexural stresses increase proportional to the square of the length
(and deflection increases proportional to the 4th power of the
length). However, the main span of the Rio-Niteroi Bridge, a box
girder bridge, is 300 metres (980 ft).
The world's longest beam bridge is
Lake Pontchartrain Causeway
Lake Pontchartrain Causeway in
Louisiana in the United States, at 23.83 miles
(38.35 km), with individual spans of 56 feet (17 m).
Beam bridges are the simplest and oldest type of bridge in use
today, and are a popular type.
A truss bridge is a bridge whose load-bearing superstructure is
composed of a truss. This truss is a structure of connected elements
forming triangular units. The connected elements (typically straight)
may be stressed from tension, compression, or sometimes both in
response to dynamic loads.
Truss bridges are one of the oldest types
of modern bridges. The basic types of truss bridges shown in this
article have simple designs which could be easily analyzed by
nineteenth and early twentieth century engineers. A truss bridge is
economical to construct owing to its efficient use of materials.
Cantilever bridges are built using cantilevers—horizontal beams
supported on only one end. Most cantilever bridges use a pair of
continuous spans that extend from opposite sides of the supporting
piers to meet at the center of the obstacle the bridge crosses.
Cantilever bridges are constructed using much the same materials &
techniques as beam bridges. The difference comes in the action of the
forces through the bridge.
Some cantilever bridges also have a smaller beam connecting the two
cantilevers, for extra strength.
The largest cantilever bridge is the 549-metre (1,801 ft) Quebec
Bridge in Quebec, Canada.
Arch bridges have abutments at each end. The weight of the bridge is
thrust into the abutments at either side. The earliest known arch
bridges were built by the Greeks, and include the Arkadiko Bridge.
With the span of 220 metres (720 ft), the
Solkan Bridge over the
Soča River at
Solkan in Slovenia is the second largest stone bridge
in the world and the longest railroad stone bridge. It was completed
in 1905. Its arch, which was constructed from over 5,000 tonnes (4,900
long tons; 5,500 short tons) of stone blocks in just 18 days, is the
second largest stone arch in the world, surpassed only by the
Friedensbrücke (Syratalviadukt) in Plauen, and the largest railroad
stone arch. The arch of the Friedensbrücke, which was built in the
same year, has the span of 90 m (295 ft) and crosses the
valley of the
Syrabach River. The difference between the two is that
Solkan Bridge was built from stone blocks, whereas the
Friedensbrücke was built from a mixture of crushed stone and cement
The world's current largest arch bridge is the
Chaotianmen Bridge over
Yangtze River with a length of 1,741 m (5,712 ft) and a
span of 552 m (1,811 ft). The bridge was opened April 29,
2009 in Chongqing, China.
Tied arch bridge
Tied arch bridges have an arch-shaped superstructure, but differ from
conventional arch bridges. Instead of transferring the weight of the
bridge and traffic loads into thrust forces into the abutments, the
ends of the arches are restrained by tension in the bottom chord of
the structure. They are also called bowstring arches.
Suspension bridges are suspended from cables. The earliest suspension
bridges were made of ropes or vines covered with pieces of bamboo. In
modern bridges, the cables hang from towers that are attached to
caissons or cofferdams. The caissons or cofferdams are implanted deep
into the bed of the lake, river or sea. Sub-types include the simple
suspension bridge, the stressed ribbon bridge, the underspanned
suspension bridge, the suspended-deck suspension bridge, and the
self-anchored suspension bridge. There is also what is sometimes
called a "semi-suspension" bridge, of which the Ferry
Burton-upon-Trent is the only one of its kind in Europe.
The longest suspension bridge in the world is the 3,909 m
Akashi Kaikyō Bridge
Akashi Kaikyō Bridge in Japan.
Cable-stayed bridges, like suspension bridges, are held up by cables.
However, in a cable-stayed bridge, less cable is required and the
towers holding the cables are proportionately higher. The first
known cable-stayed bridge was designed in 1784 by C. T. (or C. J.)
The longest cable-stayed bridge since 2012 is the
Russky Bridge in
Fixed or movable bridges
"Fixed link" redirects here. For other uses, see Intercontinental and
transoceanic fixed links and Link (other).
Bloomingdale Trail bridge from Ashland to Western in Chicago.
Most bridges are fixed bridges, meaning they have no moving parts and
stay in one place until they fail or are demolished. Temporary
bridges, such as Bailey bridges, are designed to be assembled, and
taken apart, transported to a different site, and re-used. They are
important in military engineering, and are also used to carry traffic
while an old bridge is being rebuilt. Movable bridges are designed to
move out of the way of boats or other kinds of traffic, which would
otherwise be too tall to fit. These are generally electrically
The double-decked George Washington Bridge, connecting New York City
to Bergen County, New Jersey, US, is the world's busiest bridge,
carrying 102 million vehicles annually.
See also: List of multi-level bridges
Double-decked (or double-decker) bridges have two levels, such as the
George Washington Bridge, connecting
New York City
New York City to Bergen County,
New Jersey, US, as the world's busiest bridge, carrying 102 million
vehicles annually; truss work between the roadway levels
provided stiffness to the roadways and reduced movement of the upper
level when the lower level was installed three decades after the upper
Tsing Ma Bridge
Tsing Ma Bridge and
Kap Shui Mun Bridge
Kap Shui Mun Bridge in
Hong Kong have
six lanes on their upper decks, and on their lower decks there are two
lanes and a pair of tracks for
MTR metro trains. Some double-decked
bridges only use one level for street traffic; the Washington Avenue
Minneapolis reserves its lower level for automobile and
light rail traffic and its upper level for pedestrian and bicycle
traffic (predominantly students at the University of Minnesota).
Likewise, in Toronto, the
Prince Edward Viaduct
Prince Edward Viaduct has five lanes of
motor traffic, bicycle lanes, and sidewalks on its upper deck; and a
pair of tracks for the Bloor–Danforth subway line on its lower deck.
The western span of the
San Francisco–Oakland Bay Bridge
San Francisco–Oakland Bay Bridge also has
High Level Bridge
High Level Bridge across the
River Tyne in
Newcastle upon Tyne, completed in 1849, is an early example of a
double-decked bridge. The upper level carries a railway, and the lower
level is used for road traffic. Other examples include Britannia
Bridge over the
Menai Strait and
Craigavon Bridge in Derry, Northern
Ireland. The Oresund
Malmö consists of
a four-lane highway on the upper level and a pair of railway tracks at
the lower level.
Tower Bridge in London is different example of a
double-decked bridge, with the central section consisting of a low
level bascule span and a high level footbridge.
Main article: Viaduct
A viaduct is made up of multiple bridges connected into one longer
structure. The longest and some of the highest bridges are viaducts,
such as the
Lake Pontchartrain Causeway
Lake Pontchartrain Causeway and Millau Viaduct.
The three-way Tridge
Main article: Three-way bridge
A three-way bridge has three separate spans which meet near the center
of the bridge. The bridge appears as a "T" or "Y" when viewed from
above. Three-way bridges are extremely rare. The Tridge, Margaret
Bridge, and Zanesville Y-
Bridge are examples.
Bridge types by use
A bridge can be categorized by what it is designed to carry, such as
trains, pedestrian or road traffic, a pipeline or waterway for water
transport or barge traffic. An aqueduct is a bridge that carries
water, resembling a viaduct, which is a bridge that connects points of
equal height. A road-rail bridge carries both road and rail traffic.
Overway is a term for a bridge that separates incompatible
intersecting traffic, especially road and rail. A bridge can carry
overhead power lines as does the Storstrøm Bridge.
Some bridges accommodate other purposes, such as the tower of Nový
Bridge in Bratislava, which features a restaurant, or a
bridge-restaurant which is a bridge built to serve as a restaurant.
Other suspension bridge towers carry transmission antennas.[citation
Bridges are subject to unplanned uses as well. The areas underneath
some bridges have become makeshift shelters and homes to homeless
people, and the undertimbers of bridges all around the world are spots
of prevalent graffiti. Some bridges attract people attempting suicide,
and become known as suicide bridges.
Bridge types by material
The Iron Bridge
The Iron Bridge completed in 1781 was the first cast iron bridge.
Krämerbrücke in Erfurt,
Germany - with half timbered buildings
Small stone bridge, Othonoi, Greece
The materials used to build the structure are also used to categorize
bridges. Until the end of the 18th Century, bridges were made out of
timber, stone and masonry. Modern bridges are currently built in
concrete, steel, fiber reinforced polymers (FRP), stainless steel or
combinations of those materials. Living bridges have been constructed
of live plants such as
Ficus elastica tree roots in India and
wisteria vines in Japan.
For small footbridges, the cantilevers may be simple beams; however,
large cantilever bridges designed to handle road or rail traffic use
trusses built from structural steel, or box girders built from
The cables are usually made of steel cables galvanised with
zinc, along with most of the bridge, but some bridges
are still made with steel reinforced concrete.
Stone, brick and other such materials that are strong in compression
and somewhat so in shear.
Beam bridges can use pre-stressed concrete, an inexpensive building
material, which is then embedded with rebar. The resulting bridge can
resist both compression and tension forces.
The triangular pieces of
Truss bridges are manufactured from straight
and steel bars, according to the truss bridge designs.
The World Heritage Site of
Stari Most (Old Bridge) gives its name to
the city of Mostar, Bosnia and Herzegovina
Most bridges are utilitarian in appearance, but in some cases, the
appearance of the bridge can have great importance. Often, this is the
case with a large bridge that serves as an entrance to a city, or
crosses over a main harbor entrance. These are sometimes known as
signature bridges. Designers of bridges in parks and along parkways
often place more importance to aesthetics, as well. Examples include
the stone-faced bridges along the
Taconic State Parkway
Taconic State Parkway in New York.
To create a beautiful image, some bridges are built much taller than
necessary. This type, often found in east-Asian style gardens, is
called a Moon bridge, evoking a rising full moon. Other garden bridges
may cross only a dry bed of stream washed pebbles, intended only to
convey an impression of a stream. Often in palaces a bridge will be
built over an artificial waterway as symbolic of a passage to an
important place or state of mind. A set of five bridges cross a
sinuous waterway in an important courtyard of the
Forbidden City in
Beijing, China. The central bridge was reserved exclusively for the
use of the Emperor, Empress, and their attendants.
Highway bridge treated with high-frequency impact treatment
Bridge maintenance consisting of a combination of structural health
monitoring and testing. This is regulated in country-specific engineer
standards and includes e.g. an ongoing monitoring every three to six
months, a simple test or inspection every two to three years and a
major inspection every six to ten years. In Europe, the cost of
maintenance is higher than spending on new bridges. The lifetime of
welded steel bridges can be significantly extended by aftertreatment
of the weld transitions . This results in a potential high benefit,
using existing bridges far beyond the planned lifetime.
See also: List of bridge failures
The failure of bridges is of special concern for structural engineers
in trying to learn lessons vital to bridge design, construction and
maintenance. The failure of bridges first assumed national interest
Victorian era when many new designs were being built, often
using new materials.
In the United States, the
National Bridge Inventory tracks the
structural evaluations of all bridges, including designations such as
"structurally deficient" and "functionally obsolete".
There are several methods used to monitor the stress on large
structures like bridges. The most common method is the use of an
accelerometer, which is integrated into the bridge while it is being
built. This technology is used for long-term surveillance of the
Another option for structural-integrity monitoring is "non-contact
monitoring", which uses the
Doppler effect (Doppler shift). A laser
beam from a
Laser Doppler Vibrometer is directed at the point of
interest, and the vibration amplitude and frequency are extracted from
the Doppler shift of the laser beam frequency due to the motion of the
surface. The advantage of this method is that the setup time for
the equipment is faster and, unlike an accelerometer, this makes
measurements possible on multiple structures in as short a time as
possible. Additionally, this method can measure specific points on a
bridge that might be difficult to access.
List of bridge types
List of bridge types and List of longest bridges
in the world
Bridge to nowhere
BT Centre for Major Programme Management
Cross-sea traffic ways
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Structurae – International Database and Gallery of Engineerings
Structures with over 10000 Bridges.
U.S. Federal Highway Administration
The Museum of Japanese Timber Bridges Fukuoka University
"bridge-info.org": site for bridges
Box girder bridge
Cantilever spar cable-stayed bridge
Pontoon bridge (Vlotbrug)
Suspension bridge (types)
Through arch bridge
Visual index to various types
Lists of bridges by type
List of bridges
List of road–rail bridges
List of bridge–tunnels
List of bascule bridges
List of multi-level bridges
List of toll bridges
List of cantilever bridges
Lists of bridges by size
Continuous truss bridges
Masonry arch bridges
Bridge to nowhere
See also: Architecture