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35-461: The Bloukrans Bridge is an arch bridge located near Nature's Valley , Western Cape , South Africa . Constructed by Concor between February 1980 and June 1983, the bridge stands at a height of 216m above the Bloukrans River . Its central span is 272m and the bridge is 451m in length in total. Its primary use is that of a road bridge, carrying national route N2 . Bloukrans Bridge is

70-629: A bridge in Africa is a stub . You can help Misplaced Pages by expanding it . This article about a South African building or structure is a stub . You can help Misplaced Pages by expanding it . Arch bridge Possibly the oldest existing arch bridge is the Mycenaean Arkadiko Bridge in Greece from about 1300 BC. The stone corbel arch bridge is still used by the local populace. The well-preserved Hellenistic Eleutherna Bridge has

105-512: A deck arch bridge. Any part supported from arch below may have spandrels that are closed or open. The Sydney Harbour Bridge and the Bayonne Bridge are a through arch bridge which uses a truss type arch. Also known as a bowstring arch, this type of arch bridge incorporates a tie between two opposite ends of the arch. The tie is usually the deck and is capable of withstanding the horizontal thrust forces which would normally be exerted on

140-828: A joining material such as mortar to bind the blocks together, although dry ashlar construction, metal ties, and other methods of assembly have been used. The dry ashlar of Inca architecture in Cusco and Machu Picchu is particularly fine and famous. The word is attested in Middle English and derives from the Old French aisselier , from the Latin axilla , a diminutive of axis , meaning "plank". "Clene hewen ashler" often occurs in medieval documents; this means tooled or finely worked, in contradistinction to rough-axed faces. In tile carpet installation "ashlar" refers to

175-609: A length of 167 feet (51 m) and span of 123 feet (37 m), is the world's first wholly stone open-spandrel segmental arch bridge, allowing a greater passage for flood waters. Bridges with perforated spandrels can be found worldwide, such as in China ( Zhaozhou Bridge , 7th century). Greece ( Bridge of Arta , 17th century) and Wales ( Cenarth Bridge , 18th century). In more modern times, stone and brick arches continued to be built by many civil engineers, including Thomas Telford , Isambard Kingdom Brunel and John Rennie . A key pioneer

210-448: A quantity of fill material (typically compacted rubble) above the arch in order to increase this dead-weight on the bridge and prevent tension from occurring in the arch ring as loads move across the bridge. Other materials that were used to build this type of bridge were brick and unreinforced concrete. When masonry (cut stone) is used the angles of the faces are cut to minimize shear forces. Where random masonry (uncut and unprepared stones)

245-415: A result, masonry arch bridges are designed to be constantly under compression, so far as is possible. Each arch is constructed over a temporary falsework frame, known as a centring . In the first compression arch bridges, a keystone in the middle of the bridge bore the weight of the rest of the bridge. The more weight that was put onto the bridge, the stronger its structure became. Masonry arch bridges use

280-454: A substantial part still standing and even used to carry vehicles. A more complete survey by the Italian scholar Vittorio Galliazzo found 931 Roman bridges, mostly of stone, in as many as 26 countries (including former Yugoslavia ). Roman arch bridges were usually semicircular , although a number were segmental arch bridges (such as Alconétar Bridge ), a bridge which has a curved arch that

315-430: A three-hinged bridge has hinged in all three locations. Most modern arch bridges are made from reinforced concrete . This type of bridge is suitable where a temporary centring may be erected to support the forms, reinforcing steel, and uncured concrete. When the concrete is sufficiently set the forms and falseworks are then removed. It is also possible to construct a reinforced concrete arch from precast concrete , where

350-613: A triangular corbel arch. The 4th century BC Rhodes Footbridge rests on an early voussoir arch. Although true arches were already known by the Etruscans and ancient Greeks , the Romans were – as with the vault and the dome – the first to fully realize the potential of arches for bridge construction. A list of Roman bridges compiled by the engineer Colin O'Connor features 330 Roman stone bridges for traffic, 34 Roman timber bridges and 54 Roman aqueduct bridges ,

385-429: A vertical 1/2 offset pattern. Ashlar blocks have been used in the construction of many buildings as an alternative to brick or other materials. In classical architecture , ashlar wall surfaces were often contrasted with rustication . The term is frequently used to describe the dressed stone work of prehistoric Greece and Crete , although the dressed blocks are usually much larger than modern ashlar. For example,

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420-428: Is a masonry, or stone, bridge where each successively higher course (layer) cantilevers slightly more than the previous course. The steps of the masonry may be trimmed to make the arch have a rounded shape. The corbel arch does not produce thrust, or outward pressure at the bottom of the arch, and is not considered a true arch . It is more stable than a true arch because it does not have this thrust. The disadvantage

455-399: Is capable of requiring only very thin joints between blocks, and the visible face of the stone may be quarry-faced or feature a variety of treatments: tooled, smoothly polished or rendered with another material for decorative effect. One such decorative treatment consists of small grooves achieved by the application of a metal comb. Generally used only on softer stone ashlar, this decoration

490-683: Is known as "mason's drag". Ashlar is in contrast to rubble masonry , which employs irregularly shaped stones, sometimes minimally worked or selected for similar size, or both. Ashlar is related but distinct from other stone masonry that is finely dressed but not quadrilateral, such as curvilinear and polygonal masonry . Ashlar may be coursed , which involves lengthy horizontal layers of stone blocks laid in parallel, and therefore with continuous horizontal joints. Ashlar may also be random, which involves stone blocks laid with deliberately discontinuous courses and therefore discontinuous joints both vertically and horizontally. In either case, it generally uses

525-452: Is less than a semicircle. The advantages of the segmental arch bridge were that it allowed great amounts of flood water to pass under it, which would prevent the bridge from being swept away during floods and the bridge itself could be more lightweight. Generally, Roman bridges featured wedge-shaped primary arch stones ( voussoirs ) of the same in size and shape. The Romans built both single spans and lengthy multiple arch aqueducts , such as

560-432: Is that this type of arch is not suitable for large spans. In some locations it is necessary to span a wide gap at a relatively high elevation, such as when a canal or water supply must span a valley. Rather than building extremely large arches, or very tall supporting columns (difficult using stone), a series of arched structures are built one atop another, with wider structures at the base. Roman civil engineers developed

595-402: Is used they are mortared together and the mortar is allowed to set before the falsework is removed. Traditional masonry arches are generally durable, and somewhat resistant to settlement or undermining. However, relative to modern alternatives, such bridges are very heavy, requiring extensive foundations . They are also expensive to build wherever labor costs are high. The corbel arch bridge

630-457: The tholos tombs of Bronze Age Mycenae use ashlar masonry in the construction of the so-called "beehive" dome. This dome consists of finely cut ashlar blocks that decrease in size and terminate in a central capstone . These domes are not true domes, but are constructed using the corbel arch . Ashlar masonry was also heavily used in the construction of palace facades on Crete , including Knossos and Phaistos . These constructions date to

665-610: The Alcántara Bridge . The Romans also introduced segmental arch bridges into bridge construction. The 330 m-long (1,080 ft) Limyra Bridge in southwestern Turkey features 26 segmental arches with an average span-to-rise ratio of 5.3:1, giving the bridge an unusually flat profile unsurpassed for more than a millennium. Trajan's bridge over the Danube featured open- spandrel segmental arches made of wood (standing on 40 m-high (130 ft) concrete piers). This

700-464: The MM III-LM Ib period, c.  1700 –1450 BC. In modern European masonry the blocks are generally about 35 centimetres (14 in) in height. When shorter than 30 centimetres (12 in), they are usually called small ashlar . In some Masonic groupings, which such societies term jurisdictions , ashlars are used as a symbolic metaphor for how one's personal development relates to

735-683: The Pont du Gard and Segovia Aqueduct . Their bridges featured from an early time onwards flood openings in the piers, e.g. in the Pons Fabricius in Rome (62 BC), one of the world's oldest major bridges still standing. Roman engineers were the first and until the Industrial Revolution the only ones to construct bridges with concrete , which they called Opus caementicium . The outside was usually covered with brick or ashlar , as in

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770-703: The Venetian Rialto bridge and the Fleischbrücke in Nuremberg (span-to-rise ratio 6.4:1) were founded on thousands of wooden piles, partly rammed obliquely into the grounds to counteract more effectively the lateral thrust. In China, the oldest existing arch bridge is the Zhaozhou Bridge of 605 AD, which combined a very low span-to-rise ratio of 5.2:1, with the use of spandrel arches (buttressed with iron brackets). The Zhaozhou Bridge, with

805-565: The 15th century, even featured a span length of 72 m (236 ft), not matched until 1796. Constructions such as the acclaimed Florentine segmental arch bridge Ponte Vecchio (1345) combined sound engineering (span-to-rise ratio of over 5.3 to 1) with aesthetical appeal. The three elegant arches of the Renaissance Ponte Santa Trinita (1569) constitute the oldest elliptic arch bridge worldwide. Such low rising structures required massive abutments , which at

840-436: The abutments of an arch bridge. The deck is suspended from the arch. The arch is in compression, in contrast to a suspension bridge where the catenary is in tension. A tied-arch bridge can also be a through arch bridge. An arch bridge with hinges incorporated to allow movement between structural elements. A single-hinged bridge has a hinge at the crown of the arch , a two-hinged bridge has hinges at both springing points and

875-416: The arch and the deck is known as the spandrel . If the spandrel is solid, usually the case in a masonry or stone arch bridge, the bridge is called a closed-spandrel deck arch bridge . If the deck is supported by a number of vertical columns rising from the arch, the bridge is known as an open-spandrel deck arch bridge . The Alexander Hamilton Bridge is an example of an open-spandrel arch bridge. Finally, if

910-400: The arch is built in two halves which are then leaned against each other. Many modern bridges, made of steel or reinforced concrete, often bear some of their load by tension within their structure. This reduces or eliminates the horizontal thrust against the abutments and allows their construction on weaker ground. Structurally and analytically they are not true arches but rather a beam with

945-422: The arch supports the deck only at the top of the arch, the bridge is called a cathedral arch bridge . This type of bridge has an arch whose base is at or below the deck, but whose top rises above it, so the deck passes through the arch. The central part of the deck is supported by the arch via suspension cables or tie bars, as with a tied-arch bridge . The ends of the bridge may be supported from below, as with

980-414: The design and constructed highly refined structures using only simple materials, equipment, and mathematics. This type is still used in canal viaducts and roadways as it has a pleasing shape, particularly when spanning water, as the reflections of the arches form a visual impression of circles or ellipses. This type of bridge comprises an arch where the deck is completely above the arch. The area between

1015-503: The eccentric Puente del Diablo (1282). The 14th century in particular saw bridge building reaching new heights. Span lengths of 40 m (130 ft), previously unheard of in the history of masonry arch construction, were now reached in places as diverse as Spain ( Puente de San Martín ), Italy ( Castelvecchio Bridge ) and France ( Devil's bridge and Pont Grand ) and with arch types as different as semi-circular, pointed and segmental arches. The bridge at Trezzo sull'Adda , destroyed in

1050-455: The shape of an arch. See truss arch bridge for more on this type. A modern evolution of the arch bridge is the long-span through arch bridge . This has been made possible by the use of light materials that are strong in tension such as steel and prestressed concrete. "The Romans were the first builders in Europe, perhaps the first in the world, fully to appreciate the advantages of the arch,

1085-578: The site of the world's highest commercial bridge bungee jumping, Bloukrans Bridge Bungy , operated by Face Adrenalin since 1997. The Bloukrans River below forms the border between the Eastern Cape and Western Cape provinces and is located in the Tsitsikamma region of the Garden Route . [REDACTED] Media related to Bloukrans Bridge at Wikimedia Commons This article about

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1120-609: The tenets of their lodge . As described in the explanation of the First Degree Tracing Board , in Emulation and other Masonic rituals the rough ashlar is a stone as taken directly from the quarry, and allegorically represents the Freemason prior to his initiation; a smooth ashlar (or "perfect ashlar") is a stone that has been smoothed and dressed by the experienced stonemason , and allegorically represents

1155-483: The vault and the dome." Ashlar Ashlar ( / ˈ æ ʃ l ər / ) is a cut and dressed stone , worked using a chisel to achieve a specific form, typically rectangular in shape. The term can also refer to a structure built from such stones. Ashlar is the finest stone masonry unit, and is generally rectangular ( cuboid ). It was described by Vitruvius as opus isodomum or trapezoidal . Precisely cut "on all faces adjacent to those of other stones", ashlar

1190-402: Was Jean-Rodolphe Perronet , who used much narrower piers, revised calculation methods and exceptionally low span-to-rise ratios. Different materials, such as cast iron , steel and concrete have been increasingly used in the construction of arch bridges. Stone, brick and other such materials are strong in compression and somewhat so in shear , but cannot resist much force in tension . As

1225-713: Was to be the longest arch bridge for a thousand years both in terms of overall and individual span length, while the longest extant Roman bridge is the 790 m-long (2,590 ft) long Puente Romano at Mérida . The late Roman Karamagara Bridge in Cappadocia may represent the earliest surviving bridge featuring a pointed arch. In medieval Europe, bridge builders improved on the Roman structures by using narrower piers , thinner arch barrels and higher span-to-rise ratios on bridges. Gothic pointed arches were also introduced, reducing lateral thrust, and spans increased as with

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