Civil Engineering

Bridges: everything about bridges, their types, and main parts

The construction of the Iron Bridge in Shropshire, England, in 1779 was a significant advance in bridge engineering. For the first time, cast-iron arches were employed to cross the Severn River. Wrought iron truss systems for larger bridges were developed with the Industrial Revolution in the 19th century, but iron lacks the tensile strength to carry heavy loads. Since steel has great tensile strength, much larger bridges have been constructed, many of which were inspired by Gustave Eiffel.

Stepping stones were the earliest and most basic kinds of bridges. The Sweet Track and the Post Track in England are two examples of such bridges; they date back to the Neolithic period and are about 6000 years old.  Log bridges, sometimes known as timber bridges that fall naturally or are purposefully felled or erected across waterways, were unquestionably utilized by ancient cultures. The first substantial span man-built bridges were likely made from trees that were purposefully cut down. Well in this article we’ll be answering the questions related to bridges.


  • What is a bridge?
  • What are the types of bridges?
  • What are the main parts of a bridge?
  • How to maintain bridges?
  • What are bridges made of today?
  • What are the advantages and disadvantages of bridges?


What is a bridge?

The bridge, a linking structure, forges ties between several estranged regions of a nation, two oceanic banks, or regions of two nations. A bridge is a structural wonder that is typically utilized to get over any kind of obstacle that could make life more difficult for humans. Engineers have always sought to dominate nature, and as a result, they have created bridge structures that can be used to go around the aforementioned natural barriers.

Bridges come in a wide variety of designs, each with a specific function and range of applications. The role of a bridge, the characteristics of the terrain where it is built and anchored, the material used to produce the bridge, and the amount of funding available all affect how it is designed.

Although there were substantial timber bridges in China throughout the Warring States era, the Zhaozhou Bridge, constructed between 595 and 605 AD under the Sui dynasty, is the country’s oldest stone bridge still standing. The fact that this bridge is the oldest open-spandrel stone segmental arch bridge in the entire globe adds to its historical significance. European segmental arch bridges have existed since at least the Alconétar Bridge (about the second century AD), and the huge Trajan’s Bridge (105 AD) in the Roman era had timber segmental arches with open spandrels.

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What are the types of bridges?

The following are the types of bridges;

  • Arch Bridges
  • Cable-Stayed Bridges
  • Beam Bridges
  • Suspension Bridges
  • Tied-Arch Bridges
  • Cantilever Bridges
  • Truss Bridges

Arch Bridges

Arch Bridges

An arch-shaped bridge made of stone and brick is shown above the left. A more contemporary concrete arch bridge is shown to the right. The primary structural element of an arch type of bridge is one or more arches, which are located beneath the deck. The most popular building materials at the time were stone and brick, and this method has been around for tens of thousands of years. Modern times, however, have given rise to concrete arch bridges.

The principle is the same regardless of the material: Compression is used in an arch bridge; pressure from the deck is applied laterally to the keystone and to the bridge’s supporting elements at each end (the abutments).

Roman arch bridges were mostly semicircular, while some were segmental arch bridges, which have curving arches that are smaller than semicircular (like the Alconétar Bridge).  The segmental arch bridge had the benefit of allowing a lot of flood water to travel below it, which would keep the bridge from being washed away during floods and allow for a lighter bridge structure.  Roman bridges often had major arch stones (voussoirs) that were wedge-shaped and the same size and shape. The Pont du Gard and Segovia Aqueduct are examples of Roman single-span and long multiple-arch aqueducts.

The followings are the advantages and disadvantages of arch bridges.


  • high degrees of resistance and strength (many Roman bridges still exist).
  • effectively adapted to the local environmental circumstances.
  • greater span than bridges made of beams (though less span than cantilever and suspension types).
  • can be built from a wide range of materials, including stone, brick, concrete, iron, and steel.


  • Many arches are necessary to provide a long span length.
  • takes a lot of time to build and maintain.
  • substantial side support is necessary for a good span.
  • builds with a great deal of skill.

Cable-Stayed Bridges

Cable-Stayed Bridges

The 16th-century cable-stayed bridge is still a common design for spans longer than cantilever bridges but less than the longest suspension bridges.

Deck cables are attached to one or more vertical columns, towers, or pylons in either a fan- or harp-shaped arrangement in this design. The suspension bridge, which uses vertical cables between the deck and the main support cable, should not be mistaken for this technique even if the deck depends on the cables for support. Steel or concrete pylons, post-tensioned concrete box girders, and steel rope are the most typical building components used in cable-stayed bridges.

During the late 16th century, cable-stayed bridges were being planned and built, and by the late 19th century,[2] they were in widespread use. Early versions, like the Brooklyn Bridge, sometimes blended elements from the suspension and cable-stayed systems. Early in the 20th century, pure suspension designs were more popular for bridging bigger gaps than cable-stayed designs, while various methods made of reinforced concrete were used to span narrower distances. Later in the 20th century, when the relative cost of these designs was reduced by the use of new materials, greater construction equipment, and the necessity to repair older bridges, it once again gained popularity.

The followings are the advantages and disadvantages of


  • Compared to other bridge types, construction takes place quickly.
  • rigidity is superior to suspension bridges.
  • Cost-effective.
  • can be visually appealing.
  • several design possibilities: (e.g., side-spar, cantilever-spar, multiple-span, cradle-system designs).


  • Ideal for short- to medium-distance travel (Shorter span than suspension bridges).
  • Certain places are difficult to access, which results in maintenance expenses that are higher than typical.
  • Cables may be very fatigued and susceptible to corrosion.
  • more easily vandalized (by cutting cables).
  • Not suited for regions with extreme weather or seismic risk
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Beam Bridges

Beam Bridges

The simplest kind of bridge is a beam bridge. In its most basic form, all that is required is support from abutments at each end and a crossbeam long enough to span the gap. Piers must be built to give additional support in order to attain a longer continuous span, such as above 250 ft (80 m). By doing this, you essentially build a network of linked bridges. A beam bridge may have many parallel beams supporting the deck above. A structure that is simply sustained is another name for it.

Because they lack built-in supports, unlike truss bridges, beam bridges are frequently only employed for short distances. Piers serve as the only source of support. A beam bridge becomes weaker the further its supports are spaced apart. Beam bridges rarely reach more than 250 feet as a result (80 m). This does not imply that beam bridges cannot cover large distances; rather, it simply implies that a chain of beam bridges must be connected to form a continuous span.

Beam bridges can have more than one span. There are several viaducts with many simply supported spans supported by piers, such as the Feiyunjiang Bridge in China. This contrasts with viaducts that have uninterrupted spans across the piers.

The followings are the advantages and disadvantages of beam bridges


  • Quick and easy construction.
  • Economical (if no piers needed) (if no piers needed).
  • Prefabricated modules may be produced elsewhere than at the bridge.
  • May be used in a variety of settings.
  • You can utilize a variety of materials.


  • A short distance between the supporting structures.
  • As they get older, they may begin to sag (Weight limits are sometimes needed).
  • poorly designed.
  • The cost of steel fluctuates, which has an impact on costs.
  • Steel bridge maintenance and painting are expensive and time-consuming.
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Suspension Bridges

Suspension Bridges

Early designs of suspension bridges only utilized rope and wooden planks, although the concept is not new. Due to their capacity to build wide spans across wide channels, they are a common design for long-road bridges today. The Golden Gate Bridge in San Francisco, California, is arguably the most well-known of all.

Vertical steel or reinforced concrete towers or pylons are used in suspension bridge construction. Attached The major supporting cables are located in between the pylons. These cables have a maximum diameter of 36 3/8 in (0.92 m), and they are produced from galvanized steel wire.

There are several varieties of suspension bridges in addition to the one this article described, which is the most popular variety. With the type discussed here, cables are suspended between towers, and vertical suspender cables transfer the live and dead loads of the deck below, which is where traffic passes. With this setup, the deck can be level or arched upward for more clearance. This form of suspension bridge, like other suspension bridge types, is frequently built without the use of falsework.

The followings are the advantages and disadvantages of suspension bridges

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  • The best type of bridge for achieving the longest spans with the fewest piers.
  • Many people find it to be aesthetically beautiful, providing a landmark for the neighborhood.
  • The waterway can remain open while the bridge is being built (almost all of the work takes place on the top of the bridge).
  • Flexibility: The design enables the replacement of individual deck segments.
  • Might have a high deck, giving passing ships plenty of clearance.


  • Less durable than some bridge styles.
  • A failure of the span may result from the interaction of extreme side winds and vertical pressures.
  • A suspension bridge may begin to vibrate in strong gusts.
  • They may have trouble supporting concentrated large weights (e.g., trains).
  • The collapse of the entire bridge might result from the failure of just one cable.
  • It is challenging to get to the area below the deck during construction and maintenance.
  • If the ground is soft, some suspension bridges need substantial foundation construction.

Tied-Arch Bridges

Tied-Arch Bridges

A suspended bridge and an arched bridge both have elements that are used in a tied-arch or bowstring bridge. The arch, in contrast to a conventional arched bridge, is located above the deck and uses cables that are joined vertically to support the deck. The weight is supported by this arch’s (or bow’s) compression and tension of vertical cables, which keeps the bridge incredibly stable.

Tie-arch bridges can be built with weaker foundations and placed atop elevated piers or in locations with unstable soil since the horizontal forces at the abutments are eliminated.  In addition, tied-arch bridges can be prefabricated offsite and then floated, carried, or lifted into place because they do not rely on horizontal compression forces for their integrity. The Fremont Bridge in Portland, Oregon, and the Fort Pitt Bridge in Pittsburgh, Pennsylvania, the first “computer planned” bridge of this sort, are notable examples of this style of bridge.

Below are the advantages and disadvantages of Tied-Arch Bridges


  • Extremely powerful.
  • Less pressure on the abutments.
  • Can be constructed off-site and then brought to the location.


  • For the hangers and arch to remain stable, routine maintenance is necessary.
  • The entire structure may suffer if only one hanger breaks.
  • When compared to suspension bridges, the size of each span is constrained.
  • More expensive to construct when compared to other bridge types of the same length.

Cantilever Bridges

Cantilever Bridges

Think of a diving board that is supported at only one end if you are unfamiliar with the cantilever principle. The pillars that make up a cantilever bridge are firmly fixed to the earth. From each pillar, the structure is subsequently built outward, with the horizontal beam frequently supported by diagonal bracing.

The famous image above depicts Sir John Fowler, Sir Benjamin Baker, and Kaichi Watanabe, engineers for the Forth Bridge, illustrating the cantilever principle. In this illustration, the cantilevers are Fowler and Baker, while the weight on the suspended middle span is represented by Watanabe. The cantilever beams’ anchors are represented by the bricks at either end.

For bigger bridges that transport road or rail traffic, prestressed concrete box girders or structural steel can be used to construct a cantilever bridge. When it was initially used, the steel truss cantilever bridge represented a significant advance in engineering because it could span over 1,500 feet (460 m) and could be built more readily at tricky crossings because it required little to no falsework.

Below shows the Advantages and disadvantages of the cantilever bridge.


  • A useful technique for producing long spans.
  • Each cantilever only needs support on one side.
  • suitable for situations where supporting buildings cannot be built, such as deep, rocky valleys and flood-prone regions.
  • There is little to no interference with vehicles underneath the bridge.
  • Cantilevers can be constructed simultaneously on bridges with many spans to shorten construction time.


  • It is difficult to build and maintain.
  • Requires a substantial structure, so adding additional material raises the price.
  • Not suited for regions with extreme weather or seismic risk.
  • goes through a lot of tension throughout the building (aka Negative moment).
  • The balance of compressive and tensile forces is necessary for stability.

Truss Bridges

Truss Bridges

A truss bridge can be built in a variety of ways, but you’ll note they all contain triangular pieces that are often joined together by welding or riveting. The trusses are built vertically and horizontally to accommodate compression and tension. The finished product is a building and decking area that can endure reasonably high winds.

The truss design has been used for a while and is fairly priced. The majority of buildings were first constructed of wood throughout the 19th century before switching to iron and steel later on.

Because they need a lot less material to sustain a given amount of weight, trusses are frequently used in bridge construction. They are frequently employed in railroad, military, and covered bridges.

Below shows the advantages and disadvantages of truss bridges;


  • The most durable kind of bridge.
  • Buildable off-site.
  • Lighter than other types of bridges.
  • Endures harsh weather conditions.
  • Versatile: able to support its roadway above (on a deck truss), through (a through truss), or on a lower (below-ground) truss.


  • For truss bridges to function, the building must be flawless. They must equally spread the weight.
  • The weight tolerance of older, light-traffic truss bridges may be lower.
  • Takes up a lot of room. Large triangular components that link to one other are required to support and distribute huge weights.
  • To obtain the necessary strength, there are width criteria in relation to span length.
  • Reduces the need for regular laborers and steelworkers and instead calls for architectural and technical professionals.

What are the main parts of a bridge?

Pile: A concrete support or leg for the new bridge that is inserted deeply into the ground. A pile driver is used to drive it into the earth. The pile is driven into the ground using a device called a pile driver, which operates similarly to a hammer striking a nail.

Cap – The cap, which is placed on top of a collection of piles, helps distribute pressure to the piles below.

Bent – refers to the union of the cap and the pile. They sustain the entire bridge when combined with other bents.

Girders – Girders are similar to the bridge’s arms. They run from bend to bend and hold up the decking of the bridge. They also assist in spreading pressure across the bents.

Decking – The decking is what we would refer to as the bridge’s road surface. It is supported by the girders, which are held up by bents built of caps and piles.

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How to maintain bridges?

  • Deck joints can be sealed, replaced, or eliminated. This lessens how quickly the superstructure and the components beneath the joints deteriorate.
  • Cover decks with sealant

  • Shielding the surface from potent chemicals, extreme weather, and daily wear and tear, lengthens the deck’s lifespan.
  • Erect cathodic protection devices

  • Corrosion of steel is prevented by this method.
  • Take advantage of electrochemical chloride extraction

  • Eliminating any chloride ions that may be present on or near steel components, prevents corrosion.
  • Resurface concrete

  • This should be done concurrently with other prophylactic actions. It guards against corrosion and damage to other bridge components, particularly those constructed of steel.
  • Areas that see a lot of wear and tear should be painted and treated frequently: The lifespan of the most fragile bridge components is increased as a result.
  • All steel parts should be painted and coated often

  • The greatest strategy to stop corrosion and stop the deterioration of important structural steel components—often the most expensive and challenging to replace—is to do this.
  • Replace worn-out or fracture-prone features right away

  • Treating welds and connective sections can help protect them and the areas to which they are attached from suffering long-term harm. Also, adding redundant systems is usually less expensive than repairing broken ones.
  • Install safeguards against scour

  • By doing this, failure-causing damage to substructure components is avoided.
  • Delete any debris: Chemicals in the trash and other garbage can harm structural components: It can also prevent water from flowing, which could lead to serious wear.
  • Put shields and other safety measures all around the concrete piles: The best defense against under-bridge degradation and corrosion is this.
  • Protect utility infrastructure by installing it:

  • Utility parts situated beneath bridges are susceptible to environmental and weather deterioration. Their lifespan can be prolonged for decades by installing protective equipment.
  • Routine bridge cleaning: Concrete and steel will last longer if decks, joints, and drains are cleaned together with all other superstructure and substructure components.
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What are bridges made of today?


Steel is often used in the bridge superstructure for armoring expansion joints, beams, bearings, floor beams, girders, reinforcing bars in concrete, traffic barriers, and trusses. It is utilized in the substructure for the reinforcing bars in concrete, armoring for expansion joints, anchor bolts, etc. Moreover, it is employed for the piles that support abutments and piers.


Several bridge superstructure members, including decks, pre-stressed concrete beams, curbs, walkways, and parapets, are frequently made of concrete (side traffic barrier walls). For the complete abutment, including the footings, stem (primary front wall), wing walls, cheek walls, back walls, end walls (for connecting traffic barriers), beam seats, and piers with comparable components, it is frequently used in new construction. The abutments and piers can alternatively be supported by precast or cast-in-place concrete piles.


In Harford County, asphalt has been a widely utilized material for the wearing surfaces on corrugated metal decks, timber decks, and concrete decks.


The abutments and piers were frequently constructed in the 1940s and earlier using stone. This is especially true in areas with easy access to local field stones. For the B&O railroad system, numerous magnificent stone arch bridges were constructed in the 1800s. Several of the MA & PA Railroad’s bridge abutments and piers are still intact in Harford County.


In Harford County, there are a number of decks and barriers made of wood. Moreover, it is used for the abutments and piles on one bridge as well as the beams and piles on the other.


Before 1900, iron was frequently utilized in the construction of beams and trusses. Steel took the place of iron because it is less brittle and has greater tensile strength. Iron is hardly ever used in modern bridge designs.


Products made of rubber and synthetic rubber are utilized as the material for expansion joints and bearings.


Products made of rubber and synthetic rubber are utilized as the material for expansion joints and bearings.

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What are the advantages and disadvantages of bridges?

Below shows the advantage and disadvantages of bridges


  • When the bridge is raised, no matter what height the road is, you have free passage.
  • A bridge can always be shut (by cutting the chains used to draw the bridge up)
  • Given that the gap is small enough, it can be built from one side, making a log over a stream acts something like a drawbridge but without the chains.
  • Unlike with suspension bridges, you don’t require a considerable lead-up to clear a certain height.
  • With the exception of a few movies, opening the bridges essentially blocks the path, isolating the bridged sections.
  • A bridge is simple to open and close because counterweights can be used to balance it.


  • It is preferable to have two opposing bridges than one that is twice as long because the weight of the bridge is proportionate to its length and the torque becomes increasingly problematic as the length increases. As a result, the size of the distance that your bridge can reasonably span has a limit.
  • The bridge will be blocked for a considerable amount of time after the chains have been cut.
  • Time for the bridge to open or close (obstructs traffic in both directions) – I don’t believe contemporary drawbridges open fully 90 degrees. The area of free passage is further reduced as a result.
  • The lever and anchor/fulcrum will need to be able to support a significant load if the bridge is being balanced using a counterweight.
  • Movable parts are prone to failure at any time.
  • Wires or pipes cannot be running the entire length of the bridge, but rails can be installed; nevertheless, the fit at the fulcrum must be considered. To light up the bridge on both sides, cables will need to be run along the floor of the gap or from either side.

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Bridges FAQs

What are the 5 main bridge types?

  • Beam Bridges.
  • Cantilever Bridges.
  • Arch Bridges.
  • Integral Beam Bridges.
  • Cable-Stayed Bridges.

What are bridges used for?

By offering a route that might otherwise be unequal or impractical, a bridge serves the objective of allowing people or freight to easily cross over an obstruction.

What are the 3 main types of bridges?

Beam and truss, arch, and suspension bridges are the three major types of bridges used in transportation.

What is the description of bridges?

a structure that crosses a depression or obstruction on a path or roadway (such as a river) a time, location, or method of connection or transition: a bridge that connects an island to the mainland. the construction of a link between the two cultures.

What are the 4 main components of a bridge?

  • Pile: A concrete support or leg for the new bridge that is inserted deeply into the ground.
  • Cap – The cap, which is placed on top of a collection of piles, helps distribute pressure to the piles below.
  • bent – refers to the union of the cap and the pile.
  • Girders – Girders are similar to the bridge’s arms.

What are the four main factors of a bridge?

In order to choose the best bridge types for this project, four key parameters were discovered. These elements are mentioned below and include geography, loading, aesthetics, and cost.

What are the 7 bridge names?

  • Arch Bridges.
  • Beam Bridges.
  • Cantilever Bridges.
  • Cable-Stayed Bridges.
  • Suspension Bridges.
  • Tied-Arch Bridges.
  • Truss Bridges

Which is the strongest bridge?

Resultantly, it’s feasible that end post joints with greater strength will result in the truss bridge being declared to be the strongest. My project required creating, evaluating, and contrasting bridges made of beams, trusses, and archways.

How are bridges classified?

The six basic types of bridges are the beam, truss, arch, suspension, cantilever, and cable stay.

What are bridges and their types?

There are two main categories of bridges: fixed and moveable. The basic geometry of fixed bridges, such as their arches, trusses, beams, girders, suspension, and cable-stayed types, is typically used to categorize them. For many years, steel has been employed in the building of bridges. Concrete beams are used in the construction of many small bridges today.

That’s all for this article, where the answers to these questions were discussed.

  • What is a bridge?
  • What are the types of bridges?
  • What are the main parts of a bridge?
  • How to maintain bridges?
  • What are bridges made of today?
  • What are the advantages and disadvantages of bridges?

I hope it was helpful, if so, kindly share. Thanks for reading.