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121-570: The Sydney Harbour Bridge is a steel through arch bridge in Sydney , New South Wales , Australia , spanning Sydney Harbour from the central business district (CBD) to the North Shore . The view of the bridge, the Harbour, and the nearby Sydney Opera House is widely regarded as an iconic image of Sydney, and of Australia itself. Nicknamed "The Coathanger" because of its arch-based design,

242-563: A basaltic magma to a granitic magma, but the quantities produced are small. For example, granitic rock makes up just 4% of the exposures in the South Sandwich Islands . In continental arc settings, granitic rocks are the most common plutonic rocks, and batholiths composed of these rock types extend the entire length of the arc. There are no indication of magma chambers where basaltic magmas differentiate into granites, or of cumulates produced by mafic crystals settling out of

363-399: A bridge as early as 1814, when convict and noted architect Francis Greenway reputedly proposed to Governor Lachlan Macquarie that a bridge be built from the northern to the southern shore of the harbour. In 1825, Greenway wrote a letter to the then " The Australian " newspaper stating that such a bridge would "give an idea of strength and magnificence that would reflect credit and glory on

484-436: A change of government at the 1904 NSW State election construction never began. A unique three-span bridge was proposed in 1922 by Ernest Stowe with connections at Balls Head , Millers Point , and Balmain with a memorial tower and hub on Goat Island . In 1914, John Bradfield was appointed Chief Engineer of Sydney Harbour Bridge and Metropolitan Railway Construction, and his work on the project over many years earned him

605-420: A design for a suspension bridge and won the second prize of £500. In 1902, when the outcome of the first competition became mired in controversy, Selfe won a second competition outright, with a design for a steel cantilever bridge . The selection board were unanimous, commenting that, "The structural lines are correct and in true proportion, and... the outline is graceful". However due to an economic downturn and

726-520: A diapir it would expend far too much energy in heating wall rocks, thus cooling and solidifying before reaching higher levels within the crust. Fracture propagation is the mechanism preferred by many geologists as it largely eliminates the major problems of moving a huge mass of magma through cold brittle crust. Magma rises instead in small channels along self-propagating dykes which form along new or pre-existing fracture or fault systems and networks of active shear zones. As these narrow conduits open,

847-610: A granite that is derived from partial melting of metasedimentary rocks may have more alkali feldspar, whereas a granite derived from partial melting of metaigneous rocks may be richer in plagioclase. It is on this basis that the modern "alphabet" classification schemes are based. The letter-based Chappell & White classification system was proposed initially to divide granites into I-type (igneous source) granite and S-type (sedimentary sources). Both types are produced by partial melting of crustal rocks, either metaigneous rocks or metasedimentary rocks. I-type granites are characterized by

968-565: A high content of sodium and calcium, and by a strontium isotope ratio, Sr/ Sr, of less than 0.708. Sr is produced by radioactive decay of Rb, and since rubidium is concentrated in the crust relative to the mantle, a low ratio suggests origin in the mantle. The elevated sodium and calcium favor crystallization of hornblende rather than biotite. I-type granites are known for their porphyry copper deposits. I-type granites are orogenic (associated with mountain building) and usually metaluminous. S-type granites are sodium-poor and aluminum-rich. As

1089-403: A large pneumatic rivet gun . The largest of the rivets used weighed 3.5 kg (8 lb) and was 39.5 cm (15.6 in) long. The practice of riveting large steel structures, rather than welding, was, at the time, a proven and understood construction technique, whilst structural welding had not at that stage been adequately developed for use on the bridge. At each end of the arch stands

1210-529: A large contemporary brass plaque being bolted very tightly to the side of one of the granite columns of the bridge to makes things clear. The official ceremony to mark the turning of the first sod occurred on 28 July 1923, on the spot at Milsons Point where two workshops to assist in building the bridge were to be constructed. An estimated 469 buildings on the north shore, both private homes and commercial operations, were demolished to allow construction to proceed, with little or no compensation being paid. Work on

1331-824: A much higher proportion of clay with the Cecil soil series a prime example of the consequent Ultisol great soil group. Granite is a natural source of radiation , like most natural stones. Potassium-40 is a radioactive isotope of weak emission, and a constituent of alkali feldspar , which in turn is a common component of granitic rocks, more abundant in alkali feldspar granite and syenites . Some granites contain around 10 to 20 parts per million (ppm) of uranium . By contrast, more mafic rocks, such as tonalite, gabbro and diorite , have 1 to 5 ppm uranium, and limestones and sedimentary rocks usually have equally low amounts. Many large granite plutons are sources for palaeochannel -hosted or roll front uranium ore deposits , where

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1452-519: A pair of 89-metre-high (292 ft) concrete pylons, faced with granite . The pylons were designed by the Scottish architect Thomas S. Tait , a partner in the architectural firm John Burnet & Partners. Some 250 Australian, Scottish, and Italian stonemasons and their families relocated to a temporary settlement at Moruya , 300 km (186 mi) south of Sydney, where they quarried around 18,000 m (635,664 cu ft) of granite for

1573-536: A peculiar mineralogy and geochemistry, with particularly high silicon and potassium at the expense of calcium and magnesium and a high content of high field strength cations (cations with a small radius and high electrical charge, such as zirconium , niobium , tantalum , and rare earth elements .) They are not orogenic, forming instead over hot spots and continental rifting, and are metaluminous to mildly peralkaline and iron-rich. These granites are produced by partial melting of refractory lithology such as granulites in

1694-568: A range of hills, formed by the metamorphic aureole or hornfels . Granite often occurs as relatively small, less than 100 km stock masses ( stocks ) and in batholiths that are often associated with orogenic mountain ranges. Small dikes of granitic composition called aplites are often associated with the margins of granitic intrusions . In some locations, very coarse-grained pegmatite masses occur with granite. Granite forms from silica-rich ( felsic ) magmas. Felsic magmas are thought to form by addition of heat or water vapor to rock of

1815-415: A result, they contain micas such as biotite and muscovite instead of hornblende. Their strontium isotope ratio is typically greater than 0.708, suggesting a crustal origin. They also commonly contain xenoliths of metamorphosed sedimentary rock, and host tin ores. Their magmas are water-rich, and they readily solidify as the water outgasses from the magma at lower pressure, so they less commonly make it to

1936-533: A significant obstacle and incline for the roadway. Small bridges can be hump-backed , but larger bridges such as the Old Bridge, Pontypridd may become so steep as to require steps, making their use for wheeled traffic difficult. Railways also find arched bridges difficult as they are even less tolerant of inclines. Where simple arched bridges are used for railways on flat terrain the cost of building long approach embankments may be considerable. Further issues are

2057-467: A through arch does not change the proportions or size of the arch: a large span will still require a tall arch, although this can now reach any height above the deck without obstructing traffic. The arch may also reach downwards at its sides, to either reach strong foundations or to place the roadway at a convenient height for spanning a deep valley from a plateau above. The Tyne Bridge demonstrates both of these advantages. A well-known example of this type

2178-512: A tunnel to complement the bridge. It was determined that the bridge could no longer support the increased traffic flow of the 1980s. The Sydney Harbour Tunnel was completed in August 1992 and carries only motor vehicles. The Bradfield Highway is designated as a Travelling Stock Route which means that it is permissible to herd livestock across the bridge, but only between midnight and dawn, and after giving notice of intention to do so. In practice,

2299-466: Is grus , which is often made up of coarse-grained fragments of disintegrated granite. Climatic variations also influence the weathering rate of granites. For about two thousand years, the relief engravings on Cleopatra's Needle obelisk had survived the arid conditions of its origin before its transfer to London. Within two hundred years, the red granite has drastically deteriorated in the damp and polluted air there. Soil development on granite reflects

2420-545: Is microgranite . The extrusive igneous rock equivalent of granite is rhyolite . Granitic rock is widely distributed throughout the continental crust . Much of it was intruded during the Precambrian age; it is the most abundant basement rock that underlies the relatively thin sedimentary veneer of the continents. Outcrops of granite tend to form tors , domes or bornhardts , and rounded massifs . Granites sometimes occur in circular depressions surrounded by

2541-517: Is 3–6·10 Pa·s. The melting temperature of dry granite at ambient pressure is 1215–1260 °C (2219–2300 °F); it is strongly reduced in the presence of water, down to 650 °C at a few hundred megapascals of pressure. Granite has poor primary permeability overall, but strong secondary permeability through cracks and fractures if they are present. A worldwide average of the chemical composition of granite, by weight percent, based on 2485 analyses: The medium-grained equivalent of granite

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2662-478: Is 52,800 tonnes (52,000 long tons; 58,200 short tons), with the arch itself weighing 39,000 tonnes (38,000 long tons; 43,000 short tons). About 79% of the steel, specifically those technical sections constituting the curve of the arch, was imported pre-formed from England, with the rest being sourced from the Newcastle Steelworks . On site, Dorman Long & Co set up two workshops at Milsons Point, at

2783-410: Is an excess of aluminum beyond what can be taken up in feldspars (Al 2 O 3 > CaO + K 2 O + Na 2 O) are described as peraluminous , and they contain aluminum-rich minerals such as muscovite . The average density of granite is between 2.65 and 2.75 g/cm (165 and 172 lb/cu ft), its compressive strength usually lies above 200 MPa (29,000 psi), and its viscosity near STP

2904-637: Is believed to have a mass of around 81 tonnes. It was the tallest temple in south India. Imperial Roman granite was quarried mainly in Egypt, and also in Turkey, and on the islands of Elba and Giglio . Granite became "an integral part of the Roman language of monumental architecture". The quarrying ceased around the third century AD. Beginning in Late Antiquity the granite was reused, which since at least

3025-434: Is called a binary or two-mica granite. Two-mica granites are typically high in potassium and low in plagioclase, and are usually S-type granites or A-type granites, as described below . Another aspect of granite classification is the ratios of metals that potentially form feldspars. Most granites have a composition such that almost all their aluminum and alkali metals (sodium and potassium) are combined as feldspar. This

3146-410: Is common in the continental crust of Earth, where it is found in igneous intrusions . These range in size from dikes only a few centimeters across to batholiths exposed over hundreds of square kilometers. Granite is typical of a larger family of granitic rocks , or granitoids , that are composed mostly of coarse-grained quartz and feldspars in varying proportions. These rocks are classified by

3267-518: Is constructed in place or lifted into position. In some cases, this type of arch has been created by constructing cantilevers from each side, with the shoreside ends bolted securely down into heavy piers. The incomplete channel ends are then constructed toward each other and either filled by construction or by lifting a prefabricated center section. This type of construction was used in the Sydney Harbour Bridge illustrated above, with

3388-484: Is four each way. For the morning peak hour, the lane changes on the bridge also require changes to the Warringah Freeway , with its inner western reversible carriageway directing traffic to the bridge lane numbers three and four southbound. Until September 1982, during the evening peak the tidal flow was set as six northbound and two southbound lanes. The bridge has a series of overhead gantries which indicate

3509-433: Is limited by the amount of thermal energy available, which must be replenished by crystallization of higher-melting minerals in the magma. Thus, the magma is melting crustal rock at its roof while simultaneously crystallizing at its base. This results in steady contamination with crustal material as the magma rises. This may not be evident in the major and minor element chemistry, since the minerals most likely to crystallize at

3630-399: Is not practical to support the arch from beneath during construction. In modern construction, temporary towers are erected and supported by cables anchored in the ground. Temporary cables fly from each side to support arch segments as they are constructed. When the arches are almost complete a jacking bridge is placed over or beneath the gap to force the arches apart, whence the final section

3751-404: Is permeated by sheets and channels of light granitic rock (the leucosome ). The leucosome is interpreted as partial melt of a parent rock that has begun to separate from the remaining solid residue (the melanosome). If enough partial melt is produced, it will separate from the source rock, become more highly evolved through fractional crystallization during its ascent toward the surface, and become

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3872-454: Is relieved when overlying material is removed by erosion or other processes. Chemical weathering of granite occurs when dilute carbonic acid , and other acids present in rain and soil waters, alter feldspar in a process called hydrolysis . As demonstrated in the following reaction, this causes potassium feldspar to form kaolinite , with potassium ions, bicarbonate, and silica in solution as byproducts. An end product of granite weathering

3993-411: Is some concern that some granite sold as countertops or building material may be hazardous to health. Dan Steck of St. Johns University has stated that approximately 5% of all granite is of concern, with the caveat that only a tiny percentage of the tens of thousands of granite slab types have been tested. Resources from national geological survey organizations are accessible online to assist in assessing

4114-479: Is that magma will rise through the crust as a single mass through buoyancy . As it rises, it heats the wall rocks , causing them to behave as a power-law fluid and thus flow around the intrusion allowing it to pass without major heat loss. This is entirely feasible in the warm, ductile lower crust where rocks are easily deformed, but runs into problems in the upper crust which is far colder and more brittle. Rocks there do not deform so easily: for magma to rise as

4235-1031: Is the Sydney Harbour Bridge in Australia, which is based on the Hell Gate Bridge in New York City . Other bridges include the Chaotianmen Bridge in China, the world's longest through arch bridge; Tyne Bridge of Newcastle upon Tyne ; the Bayonne Bridge that connects New York City to New Jersey , which is longer than the Sydney Harbour Bridge; the Ahwaz White Bridge ; the Bourne Bridge and Sagamore Bridge , smaller, near-twin bridges over

4356-410: Is the case when K 2 O + Na 2 O + CaO > Al 2 O 3 > K 2 O + Na 2 O. Such granites are described as normal or metaluminous . Granites in which there is not enough aluminum to combine with all the alkali oxides as feldspar (Al 2 O 3 < K 2 O + Na 2 O) are described as peralkaline , and they contain unusual sodium amphiboles such as riebeckite . Granites in which there

4477-459: Is typically orthoclase or microcline and is often perthitic . The plagioclase is typically sodium-rich oligoclase . Phenocrysts are usually alkali feldspar. Granitic rocks are classified according to the QAPF diagram for coarse grained plutonic rocks and are named according to the percentage of quartz , alkali feldspar ( orthoclase , sanidine , or microcline ) and plagioclase feldspar on

4598-428: Is uncommon, is classified simply as quartz-rich granitoid or, if composed almost entirely of quartz, as quartzolite . True granites are further classified by the percentage of their total feldspar that is alkali feldspar. Granites whose feldspar is 65% to 90% alkali feldspar are syenogranites , while the feldspar in monzogranite is 35% to 65% alkali feldspar. A granite containing both muscovite and biotite micas

4719-558: The Cahill Expressway , or the Western Distributor . Drivers on the northern side will find themselves on the Warringah Freeway , though it is easy to turn off the freeway to drive westwards into North Sydney or eastwards to Neutral Bay and beyond upon arrival on the northern side. The bridge originally only had four wider traffic lanes occupying the central space which now has six, as photos taken soon after

4840-840: The Cape Cod Canal ; the Pennybacker Bridge in Austin , Texas and as the Hernando de Soto Bridge in Memphis, Tennessee . Wylam Railway Bridge is an early through arch bridge upstream of the Tyne Bridge. The through arch bridge usually consists of two ribs, although there are examples like the Hulme Arch Bridge of through arches with a single rib. When the two arches are built in parallel planes,

4961-570: The Sydney Harbour Tunnel , with the base of the southern pylon containing the Transport for NSW maintenance shed for the bridge, and the base of the northern pylon containing the traffic management shed for tow trucks and safety vehicles used on the bridge. In 1942, the pylons were modified to include parapets and anti-aircraft guns designed to assist in both Australia's defence and general war effort. There had been plans to build

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5082-494: The foundations for the bridge. Arch bridges generate large side thrusts on their footings and so may require a solid bedrock foundation. Flattening the arch shape to avoid the humpback problem, such as for Brunel's Maidenhead bridge , increases this side thrust. It is often impossible to achieve a flat enough arch, simply owing to the limitations of the foundations – particularly in flat country. Historically, such bridges often became viaducts of multiple small arches. With

5203-571: The A-Q-P half of the diagram. True granite (according to modern petrologic convention) contains between 20% and 60% quartz by volume, with 35% to 90% of the total feldspar consisting of alkali feldspar . Granitic rocks poorer in quartz are classified as syenites or monzonites , while granitic rocks dominated by plagioclase are classified as granodiorites or tonalites . Granitic rocks with over 90% alkali feldspar are classified as alkali feldspar granites . Granitic rock with more than 60% quartz, which

5324-615: The European Union safety standards (section 4.1.1.1 of the National Health and Engineering study) and radon emission levels well below the average outdoor radon concentrations in the US. Granite and related marble industries are considered one of the oldest industries in the world, existing as far back as Ancient Egypt . Major modern exporters of granite include China, India, Italy, Brazil, Canada, Germany, Sweden, Spain and

5445-639: The Mohs hardness scale) , and tough. These properties have made granite a widespread construction stone throughout human history. The word "granite" comes from the Latin granum , a grain, in reference to the coarse-grained structure of such a completely crystalline rock. Granitic rocks mainly consist of feldspar , quartz , mica , and amphibole minerals , which form an interlocking, somewhat equigranular matrix of feldspar and quartz with scattered darker biotite mica and amphibole (often hornblende ) peppering

5566-591: The NSW Department of Public Works prepared a general design for a single-arch bridge based upon New York City 's Hell Gate Bridge . In 1922 the government of George Fuller passed the Sydney Harbour Act 1922 , specifying the construction of a high-level cantilever or arch bridge across the Harbour between Dawes Point and Milsons Point, along with construction of necessary approaches and electric railway lines, and worldwide tenders were invited for

5687-511: The United States. The Red Pyramid of Egypt ( c.  2590 BC ), named for the light crimson hue of its exposed limestone surfaces, is the third largest of Egyptian pyramids . Pyramid of Menkaure , likely dating 2510 BC, was constructed of limestone and granite blocks. The Great Pyramid of Giza (c. 2580 BC ) contains a huge granite sarcophagus fashioned of "Red Aswan Granite". The mostly ruined Black Pyramid dating from

5808-454: The angled foundations built into their sides. Once work had progressed sufficiently on the support structures, a giant creeper crane was erected on each side of the harbour. These cranes were fitted with a cradle, and then used to hoist men and materials into position to allow for erection of the steelwork. To stabilise works while building the arches, tunnels were excavated on each shore with steel cables passed through them and then fixed to

5929-418: The arches, allowing the roadway and other parts of the bridge to be constructed from the centre out. The vertical hangers were attached to the arch, and these were then joined with horizontal crossbeams. The deck for the roadway and railway were built on top of the crossbeams, with the deck itself being completed by June 1931, and the creeper cranes were dismantled. Rails for trains and trams were laid, and road

6050-544: The associated roadway as the Bradfield Highway. After they did so, there was a 21-gun salute and an Royal Australian Air Force flypast . The intruder was identified as Francis de Groot . He was convicted of offensive behaviour and fined £5 after a psychiatric test proved he was sane, but this verdict was reversed on appeal. De Groot then successfully sued the Commissioner of Police for wrongful arrest and

6171-493: The availability of iron or concrete as structural materials, it became possible to construct a through arch bridge : a bridge where the deck does not have to be carried over the top of the arch. This requires a structure that can both support the deck from the arch by tension rods, chains or cables and allow a gap in the arch, so the deck can pass through it. The first of these in particular cannot be achieved with masonry construction and requires wrought iron or steel. The use of

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6292-419: The base of the chamber are the same ones that would crystallize anyway, but crustal assimilation is detectable in isotope ratios. Heat loss to the country rock means that ascent by assimilation is limited to distance similar to the height of the magma chamber. Physical weathering occurs on a large scale in the form of exfoliation joints , which are the result of granite's expanding and fracturing as pressure

6413-437: The base of the pylons are essential to support the loads from the arch and hold its span firmly in place, but the pylons themselves have no structural purpose. They were included to provide a frame for the arch panels and to give better visual balance to the bridge. The pylons were not part of the original design, and were only added to allay public concern about the structural integrity of the bridge. Although originally added to

6534-418: The big difference in rheology between mafic and felsic magmas makes this process problematic in nature. Granitization is an old, and largely discounted, hypothesis that granite is formed in place through extreme metasomatism . The idea behind granitization was that fluids would supposedly bring in elements such as potassium, and remove others, such as calcium, to transform a metamorphic rock into granite. This

6655-410: The bridge and its approaches, is named in honour of Bradfield's contribution to the bridge. Bradfield visited the site sporadically throughout the eight years it took Dorman Long to complete the bridge. Despite having originally championed a cantilever construction and the fact that his own arched general design was used in neither the tender process nor as input to the detailed design specification (and

6776-595: The bridge by symmetrical ramps and tunnels. The eastern-side railway tracks were intended for use by a planned rail link to the Northern Beaches ; in the interim they were used to carry trams from the North Shore into a terminal within Wynyard station, and when tram services were discontinued in 1958, they were converted into extra traffic lanes. The Bradfield Highway , which is the main roadway section of

6897-534: The bridge carries rail, vehicular, bicycle and pedestrian traffic. Under the direction of John Bradfield of the New South Wales Department of Public Works , the bridge was designed and built by British firm Dorman Long of Middlesbrough , and opened in 1932. The bridge's general design, which Bradfield tasked the NSW Department of Public Works with producing, was a rough copy of the Hell Gate Bridge in New York City . The design chosen from

7018-471: The bridge coincided with the construction of a system of underground railways beneath Sydney's CBD, known today as the City Circle , and the bridge was designed with this in mind. The bridge was designed to carry six lanes of road traffic, flanked on each side by two railway tracks and a footpath. Both sets of rail tracks were linked into the underground Wynyard railway station on the south (city) side of

7139-428: The bridge itself commenced with the construction of approaches and approach spans, and by September 1926 concrete piers to support the approach spans were in place on each side of the harbour. As construction of the approaches took place, work was also started on preparing the foundations required to support the enormous weight of the arch and loadings. Concrete and granite faced abutment towers were constructed, with

7260-418: The bridge pylons. The stonemasons cut, dressed, and numbered the blocks, which were then transported to Sydney on three ships built specifically for this purpose. The Moruya quarry was managed by John Gilmore, a Scottish stonemason who emigrated with his young family to Australia in 1924, at the request of the project managers. The concrete used was also Australian-made and supplied from Kandos . Abutments at

7381-438: The bridge solely for their aesthetic value, all four pylons have now been put to use. The south-eastern pylon contains a museum and tourist centre, with a 360° lookout at the top providing views across the Harbour and city. The south-western pylon is used by Transport for NSW to support its CCTV cameras overlooking the bridge and the roads around that area. The two pylons on the north shore include venting chimneys for fumes from

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7502-538: The bridge was AU£ 6.25 million, which was not paid off in full until 1988. The bridge was formally opened on Saturday, 19 March 1932. Among those who attended and gave speeches were the Governor of New South Wales , Sir Philip Game , and the Minister for Public Works, Lawrence Ennis . The Premier of New South Wales , Jack Lang , was to open the bridge by cutting a ribbon at its southern end. However, just as Lang

7623-524: The bridge was also used to cut the ribbon at the dedication of the Bayonne Bridge , which had opened between Bayonne, New Jersey , and New York City the year before. Despite the bridge opening in the midst of the Great Depression , opening celebrations were organised by the Citizens of Sydney Organising Committee, an influential body of prominent men and politicians that formed in 1931 under

7744-458: The bridge. One of three microphones used at the opening ceremony was signed by 10 local dignitaries who officiated at the event, Philip Game, John Lang, MA Davidson, Samuel Walder, D Clyne, H Primrose, Ben Howe, John Bradfield, Lawrence Ennis and Roland Kitson. It was supplied by Amalgamated Wireless Australasia , who organised the ceremony's broadcast and collected by Philip Geeves, the AWA announcer on

7865-513: The centre median. Through arch bridge For a specific construction method, especially for masonry arches, the proportions of the arch remain similar no matter what the size: wider arches are thus required to be taller arches. For a semi-circular arch, the height is half of the span. Bridges across deep, narrow gorges can have their arch placed entirely beneath a flat roadway, but bridges in flatter country rise above their road approaches. A wide bridge may require an arch so tall as to become

7986-401: The centre of the arch, to 57 m (187 ft) at the ends next to the pylons. The arch has a span of 504 m (1,654 ft), and its summit is 134 m (440 ft) above mean sea level; expansion of the steel structure on hot days can increase the height of the arch by 18 cm (7.1 in). The total weight of the steelwork of the bridge, including the arch and approach spans,

8107-468: The chairmanship of the lord mayor to oversee the festivities. The celebrations included an array of decorated floats , a procession of passenger ships sailing below the bridge, and a Venetian Carnival . A message from a primary school in Tottenham , 515 km (320 mi) away in rural New South Wales, arrived at the bridge on the day and was presented at the opening ceremony. It had been carried all

8228-471: The colony and the Mother Country". Nothing came of Greenway's suggestions, but the idea remained alive, and many further suggestions were made during the nineteenth century. In 1840, naval architect Robert Brindley proposed that a floating bridge be built. Engineer Peter Henderson produced one of the earliest known drawings of a bridge across the harbour around 1857. A suggestion for a truss bridge

8349-629: The day. The radio is now in the collection of the Powerhouse Museum . The bridge itself was regarded as a triumph over Depression times, earning the nickname "the Iron Lung ", as it kept many Depression-era workers employed. In 2010, the average daily traffic included 204 trains, 160,435 vehicles and 1650 bicycles. From the Sydney CBD side, motor vehicle access to the bridge is via Grosvenor Street , Clarence Street , Kent Street ,

8470-615: The deafness experienced by many of the workers in later years was blamed on the project. Henri Mallard between 1930 and 1932 produced hundreds of stills and film footage which reveal at close quarters the bravery of the workers in tough Depression-era conditions. Interviews were conducted between 1982-1989 with a variety of tradesmen who worked on the building of the bridge. Among the tradesmen interviewed were drillers, riveters, concrete packers, boilermakers, riggers, ironworkers, plasterers, stonemasons, an official photographer, sleepcutters, engineers and draughtsmen. The total financial cost of

8591-491: The deliberate tension member that is the key to a tied-arch. Although visually similar, tied- and untied- through-arch bridges are quite distinct structurally and are unrelated in how they distribute their loads. In particular, cast iron bridges such as the Stanley Ferry Aqueduct may resemble tied-arch bridges, but as cast iron is weak in tension they are not structurally a tied arch. In some locations it

8712-482: The detailed design and erection process of the bridge. Architects for the contractors were from the British firm John Burnet & Partners of Glasgow , Scotland. Lawrence Ennis, of Dorman Long, served as Director of Construction and primary onsite supervisor throughout the entire build, alongside Edward Judge, Dorman Long's Chief Technical Engineer, who functioned as Consulting and Designing Engineer. The building of

8833-475: The direction of flow for each traffic lane. A green arrow pointing down to a traffic lane means the lane is open. A flashing red "X" indicates the lane is closing, but is not yet in use for traffic travelling in the other direction. A static red "X" means the lane is in use for oncoming traffic. This arrangement was introduced in January 1986, replacing a slow operation where lane markers were manually moved to mark

8954-404: The division between S-type (produced by underplating) and I-type (produced by injection and differentiation) granites, discussed below. The composition and origin of any magma that differentiates into granite leave certain petrological evidence as to what the granite's parental rock was. The final texture and composition of a granite are generally distinctive as to its parental rock. For instance,

9075-473: The early 16th century became known as spolia . Through the process of case-hardening , granite becomes harder with age. The technology required to make tempered metal chisels was largely forgotten during the Middle Ages. As a result, Medieval stoneworkers were forced to use saws or emery to shorten ancient columns or hack them into discs. Giorgio Vasari noted in the 16th century that granite in quarries

9196-534: The eastern side of the bridge, whilst a dedicated path for bicycle use runs along the western side. Between the main roadway and the western bicycle path lies the North Shore railway line . The main roadway across the bridge is known as the Bradfield Highway and is about 2.4 km (1.5 mi) long, making it one of the shortest highways in Australia. The arch is composed of two 28-panel arch trusses; their heights vary from 18 m (59 ft) at

9317-579: The first magma to enter solidifies and provides a form of insulation for later magma. These mechanisms can operate in tandem. For example, diapirs may continue to rise through the brittle upper crust through stoping , where the granite cracks the roof rocks, removing blocks of the overlying crust which then sink to the bottom of the diapir while the magma rises to take their place. This can occur as piecemeal stopping (stoping of small blocks of chamber roof), as cauldron subsidence (collapse of large blocks of chamber roof), or as roof foundering (complete collapse of

9438-713: The grotto is a highly regarded piece of Buddhist art , and along with the temple complex to which it belongs, Seokguram was added to the UNESCO World Heritage List in 1995. Rajaraja Chola I of the Chola Dynasty in South India built the world's first temple entirely of granite in the 11th century AD in Tanjore , India . The Brihadeeswarar Temple dedicated to Lord Shiva was built in 1010. The massive Gopuram (ornate, upper section of shrine)

9559-553: The heavy loads expected. In 1924, Kathleen Butler travelled to London to set up the project office within those of Dorman, Long & Co., "attending the most difficult and technical questions and technical questions in regard to the contract, and dealing with a mass of correspondence". Bradfield and his staff were ultimately to oversee the bridge design and building process as it was executed by Dorman Long and Co, whose Consulting Engineer, Sir Ralph Freeman of Sir Douglas Fox and Partners , and his associate Georges Imbault, carried out

9680-552: The last time livestock crossed the bridge was in 1999 for the Gelbvieh Cattle Congress. The bridge is equipped for tidal flow operation , permitting the direction of traffic flow on the bridge to be altered to better suit the morning and evening peak hour traffic patterns. The bridge has eight lanes, numbered one to eight from west to east. Lanes three, four and five are reversible. One and two always flow north. Six, seven, and eight always flow south. The default

9801-598: The legacy as the father of the bridge. Bradfield's preference at the time was for a cantilever bridge without piers, and in 1916 the NSW Legislative Assembly passed a bill for such a construction, however it did not proceed as the Legislative Council rejected the legislation on the basis that the money would be better spent on the war effort. Following World War I , plans to build the bridge again built momentum. Bradfield persevered with

9922-570: The lighter color minerals. Occasionally some individual crystals ( phenocrysts ) are larger than the groundmass , in which case the texture is known as porphyritic . A granitic rock with a porphyritic texture is known as a granite porphyry . Granitoid is a general, descriptive field term for lighter-colored, coarse-grained igneous rocks. Petrographic examination is required for identification of specific types of granitoids. Granites can be predominantly white, pink, or gray in color, depending on their mineralogy . The alkali feldspar in granites

10043-474: The lower crust , rather than by decompression of mantle rock, as is the case with basaltic magmas. It has also been suggested that some granites found at convergent boundaries between tectonic plates , where oceanic crust subducts below continental crust, were formed from sediments subducted with the oceanic plate. The melted sediments would have produced magma intermediate in its silica content, which became further enriched in silica as it rose through

10164-729: The lower continental crust at high thermal gradients. This leads to significant extraction of hydrous felsic melts from granulite-facies resitites. A-type granites occur in the Koettlitz Glacier Alkaline Province in the Royal Society Range, Antarctica. The rhyolites of the Yellowstone Caldera are examples of volcanic equivalents of A-type granite. M-type granite was later proposed to cover those granites that were clearly sourced from crystallized mafic magmas, generally sourced from

10285-435: The magma is inevitable once enough magma has accumulated. However, the question of precisely how such large quantities of magma are able to shove aside country rock to make room for themselves (the room problem ) is still a matter of research. Two main mechanisms are thought to be important: Of these two mechanisms, Stokes diapirism has been favoured for many years in the absence of a reasonable alternative. The basic idea

10406-426: The magma. Other processes must produce these great volumes of felsic magma. One such process is injection of basaltic magma into the lower crust, followed by differentiation, which leaves any cumulates in the mantle. Another is heating of the lower crust by underplating basaltic magma, which produces felsic magma directly from crustal rock. The two processes produce different kinds of granites, which may be reflected in

10527-408: The magmatic parent of granitic rock. The residue of the source rock becomes a granulite . The partial melting of solid rocks requires high temperatures and the addition of water or other volatiles which lower the solidus temperature (temperature at which partial melting commences) of these rocks. It was long debated whether crustal thickening in orogens (mountain belts along convergent boundaries )

10648-405: The mantle. Although the fractional crystallisation of basaltic melts can yield small amounts of granites, which are sometimes found in island arcs, such granites must occur together with large amounts of basaltic rocks. H-type granites were suggested for hybrid granites, which were hypothesized to form by mixing between mafic and felsic from different sources, such as M-type and S-type. However,

10769-485: The opening clearly show. In 1958 tram services across the bridge were withdrawn and the tracks replaced by two extra road lanes; these lanes are now the leftmost southbound lanes on the bridge and are separated from the other six road lanes by a median strip . Lanes 7 and 8 now connect the bridge to the elevated Cahill Expressway that carries traffic to the Eastern Distributor . In 1988, work began to build

10890-442: The opening festivities, a phenomenal number given that the entire population of Sydney at the time was estimated to be 1,256,000. There had also been numerous preparatory arrangements. On 14 March 1932, three postage stamps were issued to commemorate the imminent opening of the bridge. Several songs were composed for the occasion. In the year of the opening, there was a steep rise in babies being named Archie and Bridget in honour of

11011-441: The overlying crust. Early fractional crystallisation serves to reduce a melt in magnesium and chromium, and enrich the melt in iron, sodium, potassium, aluminum, and silicon. Further fractionation reduces the content of iron, calcium, and titanium. This is reflected in the high content of alkali feldspar and quartz in granite. The presence of granitic rock in island arcs shows that fractional crystallization alone can convert

11132-469: The project, fleshing out the details of the specifications and financing for his cantilever bridge proposal, and in 1921 he travelled overseas to investigate tenders. His confidential secretary Kathleen M. Butler handled all the international correspondence during his absence, her title belying her role as project manager as well as a technical adviser. On return from his travels Bradfield decided that an arch design would also be suitable and he and officers of

11253-597: The project. As a result of the tendering process, the government received twenty proposals from six companies; on 24 March 1924 the contract was awarded to Dorman Long & Co of Middlesbrough , England well known as the contractors who later built the similar Tyne Bridge in Newcastle Upon Tyne , for an arch bridge at a quoted price of AU£ 4,217,721 11s 10d. The arch design was cheaper than alternative cantilever and suspension bridge proposals, and also provided greater rigidity making it better suited for

11374-736: The reign of Amenemhat III once had a polished granite pyramidion or capstone, which is now on display in the main hall of the Egyptian Museum in Cairo (see Dahshur ). Other uses in Ancient Egypt include columns , door lintels , sills , jambs , and wall and floor veneer. How the Egyptians worked the solid granite is still a matter of debate. Tool marks described by the Egyptologist Anna Serotta indicate

11495-420: The relative percentages of quartz, alkali feldspar, and plagioclase (the QAPF classification ), with true granite representing granitic rocks rich in quartz and alkali feldspar. Most granitic rocks also contain mica or amphibole minerals, though a few (known as leucogranites ) contain almost no dark minerals. Granite is nearly always massive (lacking any internal structures), hard (falling between 6 and 7 on

11616-564: The risk factors in granite country and design rules relating, in particular, to preventing accumulation of radon gas in enclosed basements and dwellings. A study of granite countertops was done (initiated and paid for by the Marble Institute of America) in November 2008 by National Health and Engineering Inc. of USA. In this test, all of the 39 full-size granite slabs that were measured for the study showed radiation levels well below

11737-418: The rock's high quartz content and dearth of available bases, with the base-poor status predisposing the soil to acidification and podzolization in cool humid climates as the weather-resistant quartz yields much sand. Feldspars also weather slowly in cool climes, allowing sand to dominate the fine-earth fraction. In warm humid regions, the weathering of feldspar as described above is accelerated so as to allow

11858-414: The rocks often bear a close resemblance. Under these conditions, granitic melts can be produced in place through the partial melting of metamorphic rocks by extracting melt-mobile elements such as potassium and silicon into the melts but leaving others such as calcium and iron in granulite residues. This may be the origin of migmatites . A migmatite consists of dark, refractory rock (the melanosome ) that

11979-492: The roof of a shallow magma chamber accompanied by a caldera eruption.) There is evidence for cauldron subsidence at the Mt. Ascutney intrusion in eastern Vermont. Evidence for piecemeal stoping is found in intrusions that are rimmed with igneous breccia containing fragments of country rock. Assimilation is another mechanism of ascent, where the granite melts its way up into the crust and removes overlying material in this way. This

12100-466: The site of the present day Luna Park , and fabricated the steel into the girders and other required parts. The bridge is held together by six million Australian-made hand-driven rivets supplied by the McPherson company of Melbourne, the last being driven through the deck on 21 January 1932. The rivets were heated red-hot and inserted into the plates; the headless end was immediately rounded over with

12221-642: The steelwork in the towers, while day labourers manually cleaned the granite with wire brushes. The last stone of the north-west pylon was set in place on 15 January 1932, and the timber towers used to support the cranes were removed. On 19 January 1932, the first test train, a steam locomotive, safely crossed the bridge. Load testing of the bridge took place in February 1932, with the four rail tracks being loaded with as many as 96 New South Wales Government Railways steam locomotives positioned end-to-end. The bridge underwent testing for three weeks, after which it

12342-502: The structure is a parallel rib arch bridge. When the two arch ribs lean together and shorten the distance between the arches near the top, the span is a basket handle arch bridge. Many tied-arch bridges are also through-arch bridges. As well as tying the side-loads of the arch, the tension member is also at a convenient height to form the bridge deck, as for a through-arch. The converse is not true: through-arch bridges do not imply that they are tied-arch bridges, unless they also provide

12463-414: The supporting cables to the higher side of the arches removed after completion. Granite Granite ( / ˈ ɡ r æ n ɪ t / GRAN -it ) is a coarse-grained ( phaneritic ) intrusive igneous rock composed mostly of quartz , alkali feldspar , and plagioclase . It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies underground. It

12584-435: The surface than magmas of I-type granites, which are thus more common as volcanic rock (rhyolite). They are also orogenic but range from metaluminous to strongly peraluminous. Although both I- and S-type granites are orogenic, I-type granites are more common close to the convergent boundary than S-type. This is attributed to thicker crust further from the boundary, which results in more crustal melting. A-type granites show

12705-485: The tender responses was original work created by Dorman Long, who leveraged some of the design from its own Tyne Bridge . It is the tenth-longest spanning-arch bridge in the world and the tallest steel arch bridge , measuring 134 m (440 ft) from top to water level. It was also the world's widest long-span bridge, at 48.8 m (160 ft) wide, until construction of the new Port Mann Bridge in Vancouver

12826-513: The test train of the previous day, and were discovered too late to be ejected. The construction worksheds were demolished after the bridge was completed, and the land that they were on is now occupied by Luna Park. The standards of industrial safety during construction were poor by today's standards. Sixteen workers died during construction, but surprisingly only two from falling off the bridge. Several more were injured from unsafe working practices undertaken whilst heating and inserting its rivets, and

12947-497: The two halves of the arch touched for the first time. Workers riveted both top and bottom sections of the arch together, and the arch became self-supporting, allowing the support cables to be removed. On 20 August 1930 the joining of the arches was celebrated by flying the flags of Australia and the United Kingdom from the jibs of the creeper cranes. Once the arch was completed, the creeper cranes were then worked back down

13068-409: The upper sections of each half-arch to stop them collapsing as they extended outwards. Arch construction itself began on 26 October 1928. The southern end of the bridge was worked on ahead of the northern end, to detect any errors and to help with alignment. The cranes would "creep" along the arches as they were constructed, eventually meeting up in the middle. In less than two years, on 19 August 1930,

13189-502: The uranium washes into the sediments from the granite uplands and associated, often highly radioactive pegmatites. Cellars and basements built into soils over granite can become a trap for radon gas, which is formed by the decay of uranium. Radon gas poses significant health concerns and is the number two cause of lung cancer in the US behind smoking. Thorium occurs in all granites. Conway granite has been noted for its relatively high thorium concentration of 56±6 ppm. There

13310-617: The use of flint tools on finer work with harder stones, e.g. when producing the hieroglyphic inscriptions. Patrick Hunt has postulated that the Egyptians used emery , which has greater hardness. The Seokguram Grotto in Korea is a Buddhist shrine and part of the Bulguksa temple complex. Completed in 774 AD, it is an artificial grotto constructed entirely of granite. The main Buddha of

13431-416: The way from Tottenham to the bridge by relays of school children, with the final relay being run by two children from the nearby Fort Street Boys' and Girls' schools . After the official ceremonies, the public was allowed to walk across the bridge on the deck, something that would not be repeated until the 50th anniversary celebrations. Estimates suggest that between 300,000 and one million people took part in

13552-419: Was about to cut the ribbon, a man in military uniform rode up on a horse, slashing the ribbon with his sword and opening the Sydney Harbour Bridge in the name of the people of New South Wales before the official ceremony began. He was promptly arrested. The ribbon was hurriedly retied and Lang performed the official opening ceremony and Game thereafter inaugurated the name of the bridge as Sydney Harbour Bridge and

13673-591: Was anyway a rough copy of the Devil's Gate bridge produced by the NSW Works Department), Bradfield subsequently attempted to claim personal credit for Dorman Long's design. This led to a bitter argument, with Dorman Long maintaining that instructing other people to produce a copy of an existing design in a document not subsequently used to specify the final construction did not constitute personal design input on Bradfield's part. This friction ultimately led to

13794-509: Was awarded an undisclosed out of court settlement. De Groot was a member of a right-wing paramilitary group called the New Guard , opposed to Lang's leftist policies and resentful of the fact that a member of the British royal family had not been asked to open the bridge. De Groot was not a member of the regular army but his uniform allowed him to blend in with the real cavalry. This incident

13915-478: Was completed in 2012. The southern end of the bridge is located at Dawes Point in The Rocks area, and the northern end at Milsons Point on the lower North Shore . There are six original lanes of road traffic through the main roadway, plus an additional two lanes of road traffic on its eastern side, using lanes that were formerly tram tracks . Adjacent to the road traffic, a path for pedestrian use runs along

14036-428: Was declared safe and ready to be opened. The first trial run of an electric train over the bridge was successfully completed on both lines 11 March 1932. On 19 March 1932, 632 people were the first fare-paying passengers to cross the bridge by rail, paying a premium of 10 s. for the privilege, but they were not the first members of the public to do so. That distinction fell to a pair of clergymen who inadvertently boarded

14157-506: Was made in 1879, and in 1880 a high-level bridge estimated at £850,000 was proposed. In 1900, the Lyne government committed to building a new Central railway station and organised a worldwide competition for the design and construction of a harbour bridge, overseen by Minister for Public Works Edward William O'Sullivan . G.E.W. Cruttwell , a London based engineer, was awarded the first prize of £1,000. Local engineer Norman Selfe submitted

14278-496: Was one of several involving Lang and the New Guard during that year. A similar ribbon-cutting ceremony on the bridge's northern side by North Sydney's mayor, Alderman Primrose, was carried out without incident. It was later discovered that Primrose was also a New Guard member but his role in and knowledge of the de Groot incident, if any, are unclear. The pair of golden scissors used in the ribbon cutting ceremonies on both sides of

14399-405: Was sufficient to produce granite melts by radiogenic heating , but recent work suggests that this is not a viable mechanism. In-situ granitization requires heating by the asthenospheric mantle or by underplating with mantle-derived magmas. Granite magmas have a density of 2.4 Mg/m , much less than the 2.8 Mg/m of high-grade metamorphic rock. This gives them tremendous buoyancy, so that ascent of

14520-564: Was supposed to occur across a migrating front. However, experimental work had established by the 1960s that granites were of igneous origin. The mineralogical and chemical features of granite can be explained only by crystal-liquid phase relations, showing that there must have been at least enough melting to mobilize the magma. However, at sufficiently deep crustal levels, the distinction between metamorphism and crustal melting itself becomes vague. Conditions for crystallization of liquid magma are close enough to those of high-grade metamorphism that

14641-402: Was surfaced using concrete topped with asphalt. Power and telephone lines, and water, gas, and drainage pipes were also all added to the bridge in 1931. The pylons were built atop the abutment towers, with construction advancing rapidly from July 1931. Carpenters built wooden scaffolding , with concreters and masons then setting the masonry and pouring the concrete behind it. Gangers built

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