Misplaced Pages

#964035

105-599: The Denison Bridge is a heritage-listed footbridge over the Macquarie River in Bathurst, New South Wales , Australia. It is the fourth oldest metal truss bridge existing in Australia. The bridge, completed in 1870, replaced an earlier bridge that was built in 1856 and destroyed in 1867 floods. It was designed by Gustavus Alphonse Morrell and built from 1869 to 1870 by P. N. Russell & Co . The bridge structure, except for

210-443: A sustainable transport system. Footbridges are often situated to allow pedestrians to cross water or railways in areas where there are no nearby roads. They are also located across roads to let pedestrians cross safely without slowing traffic. The latter is a type of pedestrian separation structure , examples of which are particularly found near schools. The simplest type of bridge is stepping stones , so this may have been one of

315-610: A wrought iron truss span structure. It is the second oldest metal truss bridge in New South Wales after the Prince Alfred Bridge at Gundagai . The new bridge was designed on the new American Pratt truss type construction style. This is an early metal truss bridge that carries 6.1 metres of roadway and a footpath. It has nine spans in all, three timber spans of 6.7m then three wrought iron trusses : 34m, 34.5m, 34m and then three again in timber at 6.7m. Total length of

420-464: A 'new' wooden bridge across the lake that has been used to 1878 – measuring approximately 1,450 metres (4,760 ft) in length and 4 metres (13 ft) wide. On April 6, 2001, the reconstructed wooden footbridge was opened, being the longest wooden bridge in Switzerland. A clapper bridge is an ancient form of bridge found on the moors of Devon ( Dartmoor and Exmoor ) and in other upland areas of

525-660: A Historic Engineering Marker from Engineers Australia as part of its Engineering Heritage Recognition Program . [REDACTED] This Misplaced Pages article contains material from Denison Bridge , entry number 01665 in the New South Wales State Heritage Register published by the State of New South Wales (Department of Planning and Environment) 2018 under CC-BY 4.0 licence , accessed on 2 June 2018. [REDACTED] Media related to Denison Bridge at Wikimedia Commons Footbridge For rural communities in

630-514: A bar, expelling slag in the process. During the Middle Ages , water-power was applied to the process, probably initially for powering bellows, and only later to hammers for forging the blooms. However, while it is certain that water-power was used, the details remain uncertain. That was the culmination of the direct process of ironmaking. It survived in Spain and southern France as Catalan Forges to

735-582: A carbon content of less than 0.008 wt% . Bar iron is a generic term sometimes used to distinguish it from cast iron. It is the equivalent of an ingot of cast metal, in a convenient form for handling, storage, shipping and further working into a finished product. The bars were the usual product of the finery forge , but not necessarily made by that process: Wrought iron is a form of commercial iron containing less than 0.10% of carbon, less than 0.25% of impurities total of sulfur, phosphorus, silicon and manganese, and less than 2% slag by weight. Wrought iron

840-603: A disability can cross them. Types of footbridges include: The residential-scale footbridges all span a short distance and can be used for a broad range of applications. Complicated engineering is not needed and the footbridges are built with readily available materials and basic tools. Different types of design footbridges include: Footbridges can also be built in the same ways as road or rail bridges; particularly suspension bridges and beam bridges . Some former road bridges have had their traffic diverted to alternative crossings and have become pedestrian bridges; examples in

945-470: A final product. Sometimes European ironworks would skip the shingling process completely and roll the puddle balls. The only drawback to that is that the edges of the rough bars were not as well compressed. When the rough bar was reheated, the edges might separate and be lost into the furnace. The bloom was passed through rollers and to produce bars. The bars of wrought iron were of poor quality, called muck bars or puddle bars. To improve their quality,

1050-463: A high silky luster and fibrous appearance. Wrought iron lacks the carbon content necessary for hardening through heat treatment , but in areas where steel was uncommon or unknown, tools were sometimes cold-worked (hence cold iron ) to harden them. An advantage of its low carbon content is its excellent weldability. Furthermore, sheet wrought iron cannot bend as much as steel sheet metal when cold worked. Wrought iron can be melted and cast; however,

1155-434: A low scale to supply the steel to the artisan swordmakers. Osmond iron consisted of balls of wrought iron, produced by melting pig iron and catching the droplets on a staff, which was spun in front of a blast of air so as to expose as much of it as possible to the air and oxidise its carbon content. The resultant ball was often forged into bar iron in a hammer mill. In the 15th century, the blast furnace spread into what

SECTION 10

#1732851812965

1260-449: A lower melting point than iron or steel. Cast and especially pig iron have excess slag which must be at least partially removed to produce quality wrought iron. At foundries it was common to blend scrap wrought iron with cast iron to improve the physical properties of castings. For several years after the introduction of Bessemer and open hearth steel, there were different opinions as to what differentiated iron from steel; some believed it

1365-459: A modest amount of wrought iron was refined into steel , which was used mainly to produce swords , cutlery , chisels , axes , and other edged tools, as well as springs and files. The demand for wrought iron reached its peak in the 1860s, being in high demand for ironclad warships and railway use. However, as properties such as brittleness of mild steel improved with better ferrous metallurgy and as steel became less costly to make thanks to

1470-589: A number of patented processes for that, which are referred to today as potting and stamping . The earliest were developed by John Wood of Wednesbury and his brother Charles Wood of Low Mill at Egremont , patented in 1763. Another was developed for the Coalbrookdale Company by the Cranage brothers . Another important one was that of John Wright and Joseph Jesson of West Bromwich . A number of processes for making wrought iron without charcoal were devised as

1575-410: A process for manufacturing wrought iron quickly and economically. It involved taking molten steel from a Bessemer converter and pouring it into cooler liquid slag. The temperature of the steel is about 1500 °C and the liquid slag is maintained at approximately 1200 °C. The molten steel contains a large amount of dissolved gases so when the liquid steel hit the cooler surfaces of the liquid slag

1680-410: A refinery where raw coal was used to remove silicon and convert carbon within the raw material, found in the form of graphite, to a combination with iron called cementite. In the fully developed process (of Hall), this metal was placed into the hearth of the puddling furnace where it was melted. The hearth was lined with oxidizing agents such as haematite and iron oxide. The mixture was subjected to

1785-481: A single hearth for all stages. The introduction of coke for use in the blast furnace by Abraham Darby in 1709 (or perhaps others a little earlier) initially had little effect on wrought iron production. Only in the 1750s was coke pig iron used on any significant scale as the feedstock of finery forges. However, charcoal continued to be the fuel for the finery. From the late 1750s, ironmasters began to develop processes for making bar iron without charcoal. There were

1890-424: A span of about fifty feet, while, the remaining space is divided between the other three arches, the centre one being apparently somewhat larger than the two others. There are two distinct lines of roadway, separated by the middle support of the bridge: one for carriages passing eastward, and another for those passing in an opposite direction. No separate provision has yet been made for foot passengers, but I believe it

1995-412: A strong current of air and stirred with long bars, called puddling bars or rabbles, through working doors. The air, the stirring, and the "boiling" action of the metal helped the oxidizing agents to oxidize the impurities and carbon out of the pig iron. As the impurities oxidize, they formed a molten slag or drifted off as gas, while the remaining iron solidified into spongy wrought iron that floated to

2100-599: A strong or special association with a particular community or cultural group in New South Wales for social, cultural or spiritual reasons. The Denison Bridge has local significance as an engineering landmark. This significance is demonstrated by its inclusion in the Bathurst Heritage Study, the Register of the National Trust, an Historic Engineering Marker plaque from Engineers Australia (formerly IE Aust) in 1994 and

2205-469: A structure otherwise difficult to reach are referred as catwalks or cat walks . Such catwalks are located above a stage ( theater catwalk ) in a theater, between parts of a building, along the side of a bridge, on the inside of a tunnel, on the outside of any large storage tank in a refinery or elsewhere, etc. The walkway on the outside (top) of a railroad cars such as boxcars , before air brakes came into use, or on top of some covered hopper cars

SECTION 20

#1732851812965

2310-897: A total length of 2,063 metres (6,768 ft). Before it was demolished in 2011, the Hornibrook Bridge which crossed Bramble Bay in Queensland , Australia was longer than the Poughkeepsie Bridge at 2.684 km (1.668 mi). Much rural travel takes place on local footpaths , tracks and village roads. These provide essential access to water, firewood, farm plots and the classified road network. Communities and/or local government are generally responsible for this infrastructure . Pedestrian overpasses over highways or railroads are expensive, especially when elevators or long ramps for wheelchair users are required. Without elevators or ramps, people with mobility handicaps will not be able to use

2415-424: Is redshort or hot short if it contains sulfur in excess quantity. It has sufficient tenacity when cold, but cracks when bent or finished at a red heat. Hot short iron was considered unmarketable. Cold short iron, also known as coldshear , colshire , contains excessive phosphorus. It is very brittle when cold and cracks if bent. It may, however, be worked at high temperature. Historically, coldshort iron

2520-414: Is a more important measure of the quality of wrought iron. In tensile testing, the best irons are able to undergo considerable elongation before failure. Higher tensile wrought iron is brittle. Because of the large number of boiler explosions on steamboats in the early 1800s, the U.S. Congress passed legislation in 1830 which approved funds for correcting the problem. The treasury awarded a $ 1500 contract to

2625-527: Is a prominent local landmark which has played an important role in the history of Bathurst and the Central West . It was the fifth oldest metal truss bridge in Australia until recently but is still the second oldest in NSW (after Gundagai 1867). Denison Bridge was listed on the New South Wales State Heritage Register on 1 August 2003 having satisfied the following criteria. The place is important in demonstrating

2730-530: Is also called a catwalk . With the exception of those on top of railroad cars, catwalks are equipped with railings or handrails . Since the early 1980s, several charities have developed standardized footbridge designs that are sustainable for use in developing countries . The first charity to develop such designs was Helvetas, located in Zurich, Switzerland. Designs that can be sustainably and efficiently used in developing countries are typically made available to

2835-407: Is an iron alloy with a very low carbon content (less than 0.05%) in contrast to that of cast iron (2.1% to 4.5%). It is a semi-fused mass of iron with fibrous slag inclusions (up to 2% by weight), which give it a wood-like "grain" that is visible when it is etched, rusted, or bent to failure . Wrought iron is tough, malleable, ductile , corrosion resistant, and easily forge welded , but

2940-513: Is an archaic past participle of the verb "to work", and so "wrought iron" literally means "worked iron". Wrought iron is a general term for the commodity, but is also used more specifically for finished iron goods, as manufactured by a blacksmith . It was used in that narrower sense in British Customs records, such manufactured iron was subject to a higher rate of duty than what might be called "unwrought" iron. Cast iron , unlike wrought iron,

3045-435: Is brittle and cannot be worked either hot or cold. In the 17th, 18th, and 19th centuries, wrought iron went by a wide variety of terms according to its form, origin, or quality. While the bloomery process produced wrought iron directly from ore, cast iron or pig iron were the starting materials used in the finery forge and puddling furnace . Pig iron and cast iron have higher carbon content than wrought iron, but have

3150-410: Is contemplated to add that accommodation at a future time. The roadway is formed of wood, not otherwise covered than with a coating of preparation to resist the action of the weather, mixed with some rough material to give foothold to the horses passing over. The total length of the bridge is about, I should say, 400 feet. The whole building is well defended by strong side rails and balustrades, as well on

3255-491: Is deceptive. Most of the manganese, sulfur, phosphorus, and silicon in the wrought iron are incorporated into the slag fibers, making wrought iron purer than plain carbon steel. Amongst its other properties, wrought iron becomes soft at red heat and can be easily forged and forge welded . It can be used to form temporary magnets , but it cannot be magnetized permanently, and is ductile , malleable , and tough . For most purposes, ductility rather than tensile strength

Denison Bridge - Misplaced Pages Continue

3360-467: Is highly refined, with a small amount of silicate slag forged out into fibers. It comprises around 99.4% iron by mass. The presence of slag can be beneficial for blacksmithing operations, such as forge welding, since the silicate inclusions act as a flux and give the material its unique, fibrous structure. The silicate filaments in the slag also protect the iron from corrosion and diminish the effect of fatigue caused by shock and vibration. Historically,

3465-447: Is important in demonstrating the principal characteristics of a class of cultural or natural places/environments in New South Wales. The Denison Bridge is one of a number of early metal truss bridges in colonial Australia and is representative of its type. It is, however, the second oldest in New South Wales (after Gundagai) and is technologically innovative. This bridge was the first American type Pratt truss in NSW. The bridge received

3570-549: Is more difficult to weld electrically. Before the development of effective methods of steelmaking and the availability of large quantities of steel, wrought iron was the most common form of malleable iron. It was given the name wrought because it was hammered, rolled, or otherwise worked while hot enough to expel molten slag. The modern functional equivalent of wrought iron is mild steel , also called low-carbon steel. Neither wrought iron nor mild steel contain enough carbon to be hardened by heating and quenching. Wrought iron

3675-407: Is no longer manufactured commercially. Wrought iron was originally produced by a variety of smelting processes, all described today as "bloomeries". Different forms of bloomery were used at different places and times. The bloomery was charged with charcoal and iron ore and then lit. Air was blown in through a tuyere to heat the bloomery to a temperature somewhat below the melting point of iron. In

3780-450: Is no longer produced on a commercial scale. Many products described as wrought iron, such as guard rails , garden furniture , and gates are made of mild steel. They are described as "wrought iron" only because they have been made to resemble objects which in the past were wrought (worked) by hand by a blacksmith (although many decorative iron objects, including fences and gates, were often cast rather than wrought). The word "wrought"

3885-615: Is now Belgium where it was improved. From there, it spread via the Pays de Bray on the boundary of Normandy and then to the Weald in England. With it, the finery forge spread. Those remelted the pig iron and (in effect) burnt out the carbon, producing a bloom, which was then forged into bar iron. If rod iron was required, a slitting mill was used. The finery process existed in two slightly different forms. In Great Britain, France, and parts of Sweden, only

3990-400: Is of state significance for its technical sophistication and innovation. The structure incorporates an innovative and practical solution to the problem of lateral buckling of the compression top chords of each truss, which was years ahead of the theoretical solution and is of historical significance in demonstrating the development of engineering and truss bridge technology. This solution allowed

4095-400: Is the longest enclosed pedestrian bridge, completed on October 1, 2021. The 305 metre bridge was part of a $ 250 million project to UWM's offices, which converted a former warehouse and utilized shipping containers for offices, corridors, and other spaces. The Walkway Over The Hudson footbridge was originally built for trains, it was recently restored as a pedestrian walkway. The footbridge has

4200-467: Is the oldest Pratt type truss bridge in NSW and the oldest of four colonial bridges in Bathurst. Its fabrication and erection are important as it used substantial amounts of materials and skills already available in the colony with subsequent economic benefits to the government. It is significant for being in almost continual use throughout its 120-year history as a road bridge which contributed significantly to

4305-518: Is unlikely to display any archaeological significance in relation to previous occupation due to the riverine environment and unlikely to display any archaeological potential in relation to the earlier bridge. The place possesses uncommon, rare or endangered aspects of the cultural or natural history of New South Wales. The Denison Bridge is rare. It is of state significance as the fifth oldest early metal truss bridge in colonial Australia, and second oldest in NSW after Gundagai (built 1867). The place

Denison Bridge - Misplaced Pages Continue

4410-550: The Bessemer process and the Siemens–Martin process , the use of wrought iron declined. Many items, before they came to be made of mild steel , were produced from wrought iron, including rivets , nails , wire , chains , rails , railway couplings , water and steam pipes , nuts , bolts , horseshoes , handrails , wagon tires, straps for timber roof trusses , and ornamental ironwork , among many other things. Wrought iron

4515-472: The Industrial Revolution began during the latter half of the 18th century. The most successful of those was puddling, using a puddling furnace (a variety of the reverberatory furnace ), which was invented by Henry Cort in 1784. It was later improved by others including Joseph Hall , who was the first to add iron oxide to the charge. In that type of furnace, the metal does not come into contact with

4620-722: The Pont de Solférino in Paris and the Millennium Bridge in London. To ensure footbridges are accessible to disabled and other mobility-impaired people, careful consideration is nowadays also given to provision of access lifts or ramps , as required by relevant legislation (e.g. Disability Discrimination Act 1995 in the UK). Some old bridges in Venice are now equipped with a stairlift so that residents with

4725-595: The Walloon process was used. That employed two different hearths, a finery hearth for finishing the iron and a chafery hearth for reheating it in the course of drawing the bloom out into a bar. The finery always burnt charcoal, but the chafery could be fired with mineral coal , since its impurities would not harm the iron when it was in the solid state. On the other hand, the German process, used in Germany, Russia, and most of Sweden used

4830-517: The bloomery ever being used in China. The fining process involved liquifying cast iron in a fining hearth and removing carbon from the molten cast iron through oxidation . Wagner writes that in addition to the Han dynasty hearths believed to be fining hearths, there is also pictorial evidence of the fining hearth from a Shandong tomb mural dated 1st to 2nd century AD, as well as a hint of written evidence in

4935-413: The finery forge at least by the 2nd century BC, the earliest specimens of cast and pig iron fined into wrought iron and steel found at the early Han dynasty site at Tieshengguo. Pigott speculates that the finery forge existed in the previous Warring States period (403–221 BC), due to the fact that there are wrought iron items from China dating to that period and there is no documented evidence of

5040-537: The 14th century, the bridge is believed to have been originally built in the 13th century to enable pack horses to cross the river. Nowadays clapper bridges are only used as footbridges. The Kapellbrücke is a 204-metre-long (669 ft) footbridge crossing the River Reuss in the city of Lucerne in Switzerland. It is the oldest wooden covered bridge in Europe, and one of Switzerland's main tourist attractions. The bridge

5145-680: The 1960s, the price of steel production was dropping due to recycling, and even using the Aston process, wrought iron production was labor-intensive. It has been estimated that the production of wrought iron is approximately twice as expensive as that of low-carbon steel. In the United States, the last plant closed in 1969. The last in the world was the Atlas Forge of Thomas Walmsley and Sons in Bolton , Great Britain, which closed in 1973. Its 1860s-era equipment

5250-418: The 4th century AD Daoist text Taiping Jing . Wrought iron has been used for many centuries, and is the "iron" that is referred to throughout Western history. The other form of iron, cast iron , was in use in China since ancient times but was not introduced into Western Europe until the 15th century; even then, due to its brittleness, it could be used for only a limited number of purposes. Throughout much of

5355-626: The Department of Roads and foundation member of the Engineering Association of NSW. The bridge contract drawings bear Morrell's signature and that of William Christopher Bennett, Commissioner for Roads. The bridge was constructed in 1869 to 1870 by the prominent engineering firm, P. N. Russell & Co at a cost of 18,818 pounds through the NSW Public Works Department . Most of the angle irons and bars were specially rolled for

SECTION 50

#1732851812965

5460-559: The Franklin Institute to conduct a study. As part of the study, Walter R. Johnson and Benjamin Reeves conducted strength tests on boiler iron using a tester they had built in 1832 based on a design by Lagerhjelm in Sweden. Because of misunderstandings about tensile strength and ductility, their work did little to reduce failures. The importance of ductility was recognized by some very early in

5565-914: The Island of Montreal, was measured by a calibrated device as being 7,512 feet or 2,290 meters or 1.4227 miles or 2.290 kilometers long starting and ending where the treadway rises above the ground and a pedestrian could access the bridge as close as possible to the St Lawrence River. Sky Bridge 721 , the longest pedestrian suspension bridge, which spans in the Králický Sněžník mountain in the Czech Republic, opened in May 2022. The 721 metres (2,365 ft) bridge hangs 95 metres (312 ft) above ground. The United Wholesale Mortgage Pedestrian Bridge in Pontiac, Michigan

5670-536: The Middle Ages, iron was produced by the direct reduction of ore in manually operated bloomeries , although water power had begun to be employed by 1104. The raw material produced by all indirect processes is pig iron. It has a high carbon content and as a consequence, it is brittle and cannot be used to make hardware. The osmond process was the first of the indirect processes, developed by 1203, but bloomery production continued in many places. The process depended on

5775-464: The Register of the National Estate. The place has potential to yield information that will contribute to an understanding of the cultural or natural history of New South Wales. The Denison Bridge is of state significance as an engineering achievement. Through the distribution of its ironwork the fabric displays the types of forces, compression and tension generated in the members of trusses. It

5880-498: The UK include The Iron Bridge at Ironbridge , Shropshire , the Old Bridge at Pontypridd and Windsor Bridge at Windsor, Berkshire . Most footbridges are equipped with guard rails to reduce the risk of pedestrians falling. Where they pass over busy roads or railways, they may also include a fence or other such barrier to prevent pedestrians from jumping, or throwing projectiles onto

5985-498: The United Kingdom including Snowdonia and Anglesey , Cumbria , Yorkshire and Lancashire . It is formed by large flat slabs of stone, often granite or schist , supported on stone piers (across rivers), or resting on the banks of streams. Although often credited with prehistoric origin, most were erected in medieval times, and some in later centuries. A famous example is found in the village of Postbridge . First recorded in

6090-451: The bars were cut up, piled and tied together by wires, a process known as faggoting or piling. They were then reheated to a welding state, forge welded, and rolled again into bars. The process could be repeated several times to produce wrought iron of desired quality. Wrought iron that has been rolled multiple times is called merchant bar or merchant iron. The advantage of puddling was that it used coal, not charcoal as fuel. However, that

6195-476: The bridge and supported off it, are service pipes. It was reported as being in fair to good condition and in need of regular maintenance as at 23 April 2003. The first Denison Bridge was a three span laminated bow-string arch British type bridge commenced in January 1855 and completed the following year. It was opened on New Year's Day 1856, and named in honour of the then Governor-General Sir William Denison , who

6300-480: The bridge is 474 ft (143.5m). The main spans consist of wrought iron pony trusses of the Pratt type. Support piers consist of timber piles under the approach spans and four pairs of cast iron cylinders 1.83m diameter braced with wrought iron crossed rods. The ten panel Pratt trusses are simply supported and have horizontally positioned I-sections for the upper chords and sloping end diagonals, but flat metal strips for

6405-567: The bridge was gained through angular sculptures of four winged lions crowning the abutments . They were designed by sculptor Pavel Sokolov (1764-1835), who also contributed lions for Bridge of Lions . Design of footbridges normally follows the same principles as for other bridges. However, because they are normally significantly lighter than vehicular bridges, they are more vulnerable to vibration and therefore dynamics effects are often given more attention in design. International attention has been drawn to this issue in recent years by problems on

SECTION 60

#1732851812965

6510-413: The course of the smelt, slag would melt and run out, and carbon monoxide from the charcoal would reduce the ore to iron, which formed a spongy mass (called a "bloom") containing iron and also molten silicate minerals (slag) from the ore. The iron remained in the solid state. If the bloomery were allowed to become hot enough to melt the iron, carbon would dissolve into it and form pig or cast iron, but that

6615-412: The course, or pattern, of cultural or natural history in New South Wales. Denison Bridge is of state significance as the fifth oldest metal truss bridge in Australia until recently and the second oldest in NSW (after Gundagai 1867). Further, the bridge is a significant technical accomplishment in the management of compressive and tension forces in metal truss members. Its design and innovative solution to

6720-728: The deck, is original and in excellent condition and for over 120 years the bridge carried the Great Western Highway over the Macquarie River. In the early 1990s a realignment of the Great Western Highway resulted in the Evans Bridge replacing the Denison Bridge, with the latter converted to pedestrian traffic only. It was added to the New South Wales State Heritage Register on 1 August 2003, having earlier been listed on

6825-473: The developing world, a footbridge may be a community's only access to medical clinics, schools, businesses and markets. Simple suspension bridge designs have been developed to be sustainable and easily constructed in such areas using only local materials and labor. An enclosed footbridge between two buildings is sometimes known as a skyway . Bridges providing for both pedestrians and cyclists are often referred to as greenbridges and form an important part of

6930-580: The development of the blast furnace, of which medieval examples have been discovered at Lapphyttan , Sweden and in Germany . The bloomery and osmond processes were gradually replaced from the 15th century by finery processes, of which there were two versions, the German and Walloon. They were in turn replaced from the late 18th century by puddling , with certain variants such as the Swedish Lancashire process . Those, too, are now obsolete, and wrought iron

7035-590: The earliest types of footbridge. Neolithic people also built a form of a boardwalk across marshes, of which the Sweet Track , and the Post Track are examples from England, that are around 6000 years old. Undoubtedly ancient peoples would also have used log bridges ; that is a timber bridge that fall naturally or are intentionally felled or placed across streams. Some of the first man-made bridges with significant span were probably intentionally felled trees. Among

7140-432: The fuel, and so is not contaminated by its impurities. The heat of the combustion products passes over the surface of the puddle and the roof of the furnace reverberates (reflects) the heat onto the metal puddle on the fire bridge of the furnace. Unless the raw material used is white cast iron, the pig iron or other raw product of the puddling first had to be refined into refined iron , or finers metal. That would be done in

7245-401: The gases were liberated. The molten steel then froze to yield a spongy mass having a temperature of about 1370 °C. The spongy mass would then be finished by being shingled and rolled as described under puddling (above). Three to four tons could be converted per batch with the method. Steel began to replace iron for railroad rails as soon as the Bessemer process for its manufacture

7350-528: The government engineers W. C. Bennett and G. A Morell; and P N Russell, who formed P. N. Russell and Co and was a major benefactor of the University of Sydney . The Denison Bridge is also significant for its association, through its name, with Sir William Denison, Governor of New South Wales 1855–1861. The place is important in demonstrating aesthetic characteristics and/or a high degree of creative or technical achievement in New South Wales. The Denison Bridge

7455-430: The iron. The included slag in wrought iron also imparts corrosion resistance. Antique music wire , manufactured at a time when mass-produced carbon-steels were available, was found to have low carbon and high phosphorus; iron with high phosphorus content, normally causing brittleness when worked cold, was easily drawn into music wires. Although at the time phosphorus was not an easily identified component of iron, it

7560-574: The job at P. N. Russell & Co's Pyrmont Rolling Mills and at Bathurst's two iron foundries of that time, including the nearby Denison Foundry. Only heavy iron plates and bars were imported. The cast-iron cylinders used in the piers were cast at P. N. Russell & Co's foundry in Sydney, mainly using pig-iron from the Fitzroy Iron Works . Like the first bridge, the new one was opened by the Governor of

7665-400: The length of the bridge to approach the structural limit of truss bridge technology. The clean, open arrangement of members and joints made for easy maintenance which contributed greatly to its long service life. Spanning the Macquarie River and Morse and Berry Parks, the Denison Bridge is locally significant as a prominent engineering landmark and enjoys a picturesque setting. The place has

7770-504: The mid 19th century, in Austria as the stuckofen to 1775, and near Garstang in England until about 1770; it was still in use with hot blast in New York in the 1880s. In Japan the last of the old tatara bloomeries used in production of traditional tamahagane steel, mainly used in swordmaking, was extinguished only in 1925, though in the late 20th century the production resumed on

7875-584: The north bank of the River Arno until it crosses the river at Ponte Vecchio . It was built in five months by order of Duke Cosimo I de' Medici in 1565, to the design of Giorgio Vasari . Bank Bridge is a famous 25 metre long pedestrian bridge crossing the Griboedov Canal in Saint Petersburg , Russia. Like other bridges across the canal, the existing structure dates from 1826. The special popularity of

7980-502: The now-defunct Register of the National Estate in 1978. Despite the growing importance of Bathurst as the principal urban centre over the Blue Mountains, the Macquarie River, which flows past the town on the Sydney side, was not bridged until 1856. After years of local agitation, a long timber bridge with five laminated timber arches was started in 1855 and was opened on 1 January 1856 by the Governor, Sir William Denison . A bullock

8085-637: The oldest timber bridges is the Holzbrücke Rapperswil-Hurden crossing upper Lake Zürich in Switzerland; the prehistoric timber piles discovered to the west of the Seedamm date back to 1523 B.C. The first wooden footbridge led across Lake Zürich , followed by several reconstructions at least until the late 2nd century AD, when the Roman Empire built a 6-metre-wide (20 ft) wooden bridge. Between 1358 and 1360, Rudolf IV, Duke of Austria , built

8190-405: The outer sides as on the inner line. The three are uniform. The whole of the upper part, above the roadway, is painted of a light colour, and has a very airy appearance. That below the road and under water is covered with tar, &a., and remains of its natural colour, relieving, very much, the appearance of the upper works of the bridge, and giving it a light appearance when viewed from the banks of

8295-440: The pressures of compression and tension is of historical significance in demonstrating the development of engineering and truss bridge technology. Completed in 1870, it replaces an earlier bridge that was opened in 1856 and destroyed in 1867. The present bridge is a metal truss bridge and is currently the fourth oldest existing Australian metal trusses, following Hawthorn (1861), Gundagai Road Bridge (1867) and Redesdale (1868). It

8400-666: The product is no longer wrought iron, since the slag stringers characteristic of wrought iron disappear on melting, so the product resembles impure, cast, Bessemer steel. There is no engineering advantage to melting and casting wrought iron, as compared to using cast iron or steel, both of which are cheaper. Due to the variations in iron ore origin and iron manufacture, wrought iron can be inferior or superior in corrosion resistance, compared to other iron alloys. There are many mechanisms behind its corrosion resistance. Chilton and Evans found that nickel enrichment bands reduce corrosion. They also found that in puddled, forged, and piled iron,

8505-660: The public gratis. The record for the longest footbridge in the world was claimed by then New York State Governor David Paterson in a 2009 article about the walkway across the Hudson River at Poughkeepsie, New York . On July 22, 2017, the Champlain Bridge Ice Structure ( French : l'Estacade Champlain ), a bridge built for bicycles and foot traffic only to parallel the Champlain Bridge from Brossard, Quebec west to Nun's Island (L'ile Des Soeurs) &

8610-512: The river. Returning to the upper works. On a buttress, at either end of the bridge, is raised a lamp, the light from which will serve to show the divisions of the track at night. The approaches to the bridge, on either side, have been well defended, and led up to, by strong fencing-not the primitive split-post and rail bush stuff, but good, legitimate, strong post and rail, well painted. A very good arrangement has been contrived to prevent collision. It consists merely in an application of those "rules of

8715-543: The road" which are practically on the road so little attended to. The Denison Bridge, a three-span wrought iron bridge, is an early metal truss bridge built in 1870. Its advanced design was a major engineering achievement at the time and represents the maximum achievable by truss spans. The bridge is associated with three important colonial engineers: William Christopher Bennett (Commissioner and Engineer for Roads), Gustavus Alphonse Morrell (Assistant Engineer and designer) and Peter Nicol Russell (P N Russell & Co). The bridge

8820-531: The same manner as mild steel, but the presence of oxide or inclusions will give defective results. The material has a rough surface, so it can hold platings and coatings better than smooth steel. For instance, a galvanic zinc finish applied to wrought iron is approximately 25–40% thicker than the same finish on steel. In Table 1, the chemical composition of wrought iron is compared to that of pig iron and carbon steel . Although it appears that wrought iron and plain carbon steel have similar chemical compositions, that

8925-430: The social stability and growth of Bathurst, making possible the continuous flow of people and goods between Sydney and the western districts of New South Wales. The place has a strong or special association with a person, or group of persons, of importance of cultural or natural history of New South Wales's history. The Denison Bridge is of state significance for its associations with three important colonial engineers:

9030-512: The structure. People may prefer to walk across a busy road rather than climb a bridge. It is recommended that overpasses should only be used where the number of users justify the costs. Narrow, enclosed structures can result in perceptions of low personal security among users. Wider structures and good lighting can help reduce this. A bicycle bridge is a bridge designed to be accessible to both bicycles and pedestrians or in some cases only to bicycles. Wrought iron Wrought iron

9135-477: The tension bottom chords and for the tension diagonals. There are metal stringers on metal cross girders, the whole being located at about the mid depth of the main trusses. The piers are twin metal cylinders. The bridge has four lamp standards, two at each end, and in the centre two signs. On an interpretive sign about the river and people swimming there, and the original makers sign stating : "DENISON BRIDGE P. N.RUSSELL & Co. BUILDERS - SYDNEY 1870" . Beside

9240-512: The time, who was now the Earl of Belmore . Denison had left the colony in 1861 for Madras and then to retirement in England, where he died in 1871. But the new bridge, opened in June 1870, was the replacement of the Denison Bridge of 1856 and the name of Denison was retained. Although incorporated in the original design, footways were never built as part of the bridge. A steel footbridge was erected in 1950, on

9345-465: The top of the puddle and was fished out of the melt as puddle balls, using puddle bars. There was still some slag left in the puddle balls, so while they were still hot they would be shingled to remove the remaining slag and cinder. That was achieved by forging the balls under a hammer, or by squeezing the bloom in a machine. The material obtained at the end of shingling is known as bloom. The blooms are not useful in that form, so they were rolled into

9450-414: The traffic below. It was originally usual for passengers to cross from one railway platform to another by stepping over the tracks, but from the mid-19th century onwards safety demanded the provision of a footbridge (or underpass ) at busier places. However, in some quieter areas, crossing the line by walking over the tracks is possible. Narrow footbridges or walkways to allow workers access to parts of

9555-574: The upstream side, by the Department of Main Roads . In 1964-65: six piles were driven under the timber approach spans, 23 stringers were replaced, 6 round timber girders renewed, longitudinal sheeting replaced and deck bitumen sealed, timber decking replaced by high tensile bolts in three top chord joints, expansion bearings were repaired and one girder replaced. The deck was emulsion-sprayed and grit-covered. Further repairs in 1975-76 cost $ 11,377. A concrete deck

9660-560: The working-over of the metal spread out copper, nickel, and tin impurities that produce electrochemical conditions that slow down corrosion. The slag inclusions have been shown to disperse corrosion to an even film, enabling the iron to resist pitting. Another study has shown that slag inclusions are pathways to corrosion. Other studies show that sulfur in the wrought iron decreases corrosion resistance, while phosphorus increases corrosion resistance. Chloride ions also decrease wrought iron's corrosion resistance. Wrought iron may be welded in

9765-479: Was adopted (1865 on). Iron remained dominant for structural applications until the 1880s, because of problems with brittle steel, caused by introduced nitrogen, high carbon, excess phosphorus, or excessive temperature during or too-rapid rolling. By 1890 steel had largely replaced iron for structural applications. Sheet iron (Armco 99.97% pure iron) had good properties for use in appliances, being well-suited for enamelling and welding, and being rust-resistant. In

9870-484: Was considered sufficient for nails . Phosphorus is not necessarily detrimental to iron. Ancient Near Eastern smiths did not add lime to their furnaces. The absence of calcium oxide in the slag, and the deliberate use of wood with high phosphorus content during the smelting, induces a higher phosphorus content (typically <0.3%) than in modern iron (<0.02–0.03%). Analysis of the Iron Pillar of Delhi gives 0.11% in

9975-515: Was hypothesized that the type of iron had been rejected for conversion to steel but excelled when tested for drawing ability. During the Han dynasty (202 BC – 220 AD), new iron smelting processes led to the manufacture of new wrought iron implements for use in agriculture, such as the multi-tube seed drill and iron plough . In addition to accidental lumps of low-carbon wrought iron produced by excessive injected air in ancient Chinese cupola furnaces . The ancient Chinese created wrought iron by using

10080-419: Was laid in 1981. In use for over 120 years as a road bridge, its service life was interrupted only for a 9-day repair period in the 1960s. It was superseded by a prestressed concrete bridge upstream and closed to vehicular traffic in the early 1990s and adapted for use as a footbridge. Denison Bridge was an advanced design for its period and a major engineering achievement, it was the maximum span possible with

10185-471: Was moved to the Blists Hill site of Ironbridge Gorge Museum for preservation. Some wrought iron is still being produced for heritage restoration purposes, but only by recycling scrap. The slag inclusions, or stringers , in wrought iron give it properties not found in other forms of ferrous metal. There are approximately 250,000 inclusions per square inch. A fresh fracture shows a clear bluish color with

10290-445: Was not the intention. However, the design of a bloomery made it difficult to reach the melting point of iron and also prevented the concentration of carbon monoxide from becoming high. After smelting was complete, the bloom was removed, and the process could then be started again. It was thus a batch process, rather than a continuous one such as a blast furnace. The bloom had to be forged mechanically to consolidate it and shape it into

10395-528: Was of little advantage in Sweden, which lacked coal. Gustaf Ekman observed charcoal fineries at Ulverston , which were quite different from any in Sweden. After his return to Sweden in the 1830s, he experimented and developed a process similar to puddling but used firewood and charcoal, which was widely adopted in the Bergslagen in the following decades. In 1925, James Aston of the United States developed

10500-434: Was on a tour of inspection of the Bathurst region. The first bridge lasted only 11 years, until it was destroyed by floods in 1867. The following article of the time provides great detail of the construction and the features of the first Denison Bridge: The bridge is built of wood, strengthened in parts by iron rods; it has five arches, so to speak, built upon the suspension principle. The arches at either end are small, having

10605-524: Was opened by a local entrepreneur, George Ranken (frequently quoted as Rankin): this bridge was known as the Eglinton Bridge or Rankin's Bridge. The Denison Bridge was washed away by the great flood of 1867 and its debris also destroyed Rankin's Bridge, so after eleven years of having two bridges, Bathurst again found itself with only a ford or a ferry to cross the Macquarie. A narrow temporary wooden bridge

10710-806: Was originally built c. 1365 as part of Lucerne's fortifications. An early example of a skyway is the Vasari Corridor , an elevated, enclosed passageway in Florence , Italy, which connects the Palazzo Vecchio with the Palazzo Pitti . Beginning on the south side of the Palazzo Vecchio, it then joins the Uffizi Gallery and leaves on its south side, crossing the Lungarno dei Archibusieri and then following

10815-412: Was put across near the remains of the Denison Bridge later in 1867, but this was closed for safety reasons in June 1868. The government recognised that a permanent replacement was urgently needed. A new site was chosen 100 metres downstream from the first Denison Bridge and a realignment was made to the road approaches. The new Denison Bridge was designed by Gustavus Alphonse Morrell, Assistant Engineer to

10920-470: Was roasted on a spit and 3000 people celebrated the new bridge, named after the Governor. This was the last "official" bridge designed by the Colonial Architect's Department under its brief direction by architect and engineer, William Weaver (1828–68). It was supervised by his Clerk of Works, William Downey, during 1855. Eleven days later another bridge over the Macquarie River a kilometre downstream

11025-473: Was the chemical composition and others that it was whether the iron heated sufficiently to melt and "fuse". Fusion eventually became generally accepted as relatively more important than composition below a given low carbon concentration. Another difference is that steel can be hardened by heat treating . Historically, wrought iron was known as "commercially pure iron"; however, it no longer qualifies because current standards for commercially pure iron require

#964035