A suspension bridge is a type of bridge in which the deck is hung below suspension cables on vertical suspenders. The first modern examples of this type of bridge were built in the early 1800s. Simple suspension bridges, which lack vertical suspenders, have a long history in many mountainous parts of the world; this type of bridge has cables suspended between towers, plus vertical suspender cables that carry the weight of the deck below, upon which traffic crosses. This arrangement allows the deck to arc upward for additional clearance. Like other suspension bridge types, this type is constructed without falsework; the suspension cables must be anchored at each end of the bridge, since any load applied to the bridge is transformed into a tension in these main cables. The main cables continue beyond the pillars to deck-level supports, further continue to connections with anchors in the ground; the roadway is supported by called hangers. In some circumstances, the towers may sit on a bluff or canyon edge where the road may proceed directly to the main span, otherwise the bridge will have two smaller spans, running between either pair of pillars and the highway, which may be supported by suspender cables or may use a truss bridge to make this connection.
In the latter case there will be little arc in the outboard main cables. The earliest suspension bridges were ropes slung across a chasm, with a deck at the same level or hung below the ropes such that the rope had a catenary shape; the Tibetan saint and bridge-builder Thangtong Gyalpo originated the use of iron chains in his version of simple suspension bridges. In 1433, Gyalpo built eight bridges in eastern Bhutan; the last surviving chain-linked bridge of Gyalpo's was the Thangtong Gyalpo Bridge in Duksum en route to Trashi Yangtse, washed away in 2004. Gyalpo's iron chain bridges did not include a suspended deck bridge, the standard on all modern suspension bridges today. Instead, both the railing and the walking layer of Gyalpo's bridges used wires; the stress points. Before the use of iron chains it is thought that Gyalpo used ropes from twisted willows or yak skins, he may have used bound cloth. The first iron chain suspension bridge in the Western world was the Jacob's Creek Bridge in Westmoreland County, designed by inventor James Finley.
Finley's bridge was the first to incorporate all of the necessary components of a modern suspension bridge, including a suspended deck which hung by trusses. Finley patented his design in 1808, published it in the Philadelphia journal, The Port Folio, in 1810. Early British chain bridges included the Dryburgh Abbey Bridge and 137 m Union Bridge, with spans increasing to 176 m with the Menai Bridge, "the first important modern suspension bridge"; the first chain bridge on the German speaking territories was the Chain Bridge in Nuremberg. The Clifton Suspension Bridge is one of the longest of the parabolic arc chain type; the current Marlow suspension bridge was designed by William Tierney Clark and was built between 1829 and 1832, replacing a wooden bridge further downstream which collapsed in 1828. It is the only suspension bridge across the non-tidal Thames; the Széchenyi Chain Bridge, spanning the River Danube in Budapest, was designed by William Clark and it is a larger scale version of Marlow bridge.
An interesting variation is Thornewill and Warham's Ferry Bridge in Burton-on-Trent, where the chains are not attached to abutments as is usual, but instead are attached to the main girders, which are thus in compression. Here, the chains are made from flat wrought iron plates, eight inches wide by an inch and a half thick, rivetted together; the first wire-cable suspension bridge was the Spider Bridge at Falls of Schuylkill, a modest and temporary footbridge built following the collapse of James Finley's nearby Chain Bridge at Falls of Schuylkill. The footbridge's span was 124 m. Development of wire-cable suspension bridges dates to the temporary simple suspension bridge at Annonay built by Marc Seguin and his brothers in 1822, it spanned only 18 m. The first permanent wire cable suspension bridge was Guillaume Henri Dufour's Saint Antoine Bridge in Geneva of 1823, with two 40 m spans; the first with cables assembled in mid-air in the modern method was Joseph Chaley's Grand Pont Suspendu in Fribourg, in 1834.
In the United States, the first major wire-cable suspension bridge was the Wire Bridge at Fairmount in Philadelphia, Pennsylvania. Designed by Charles Ellet, Jr. and completed in 1842, it had a span of 109 m. Ellet's Niagara Falls Suspension Bridge was abandoned before completion, it was used as scaffolding for John A. Roebling's double decker railroad and carriage bridge; the Otto Beit Bridge was the first modern suspension bridge outside the United States built with parallel wire cables. The main forces in a suspension bridge of any type are tension in the cables and compression in the pillars. Since all the force on the pillars is vertically downwards and they are stabilized by the main cables, the pillars can be made quite slender, as on the Severn Bridge, on the Wales-England border. In a suspended deck bridge, cables suspended via towers hold up the road deck; the weight is transferred by the cables to the towers, which in turn transfer the weight to the ground. Assuming a negligible weight as compared to the weight of the deck and vehicles being supported, the main cables of a suspension bridge will form a parabola (very similar
A sidewalk or pavement known as a footpath or footway, is a path along the side of a road. A sidewalk may accommodate moderate changes in grade and is separated from the vehicular section by a curb. There may be a median strip or road verge either between the sidewalk and the roadway or between the sidewalk and the boundary. In some places, the same term may be used for a paved path, trail or footpath, not next to a road, for example, a path through a park; the term "sidewalk" is preferred in most of North America, along with many other countries worldwide that are not members of the Commonwealth of Nations. The term "pavement" is more common in the United Kingdom, as well as parts of the Mid-Atlantic United States such as Philadelphia and parts of New Jersey. Many Commonwealth countries use the term "footpath"; the professional, civil engineering and legal term for this in North America is "sidewalk" while in the United Kingdom it is "footway". In the United States, the term sidewalk is used for the pedestrian path beside a road.
"Shared use paths" or "multi-use paths" are available for use by both bicyclists. "Walkway" is a more comprehensive term that includes stairs, ramps and related structures that facilitate the use of a path as well as the sidewalk. In the UK, the term "footpath" is used for paths that do not abut a roadway; the term "shared-use path" is used where cyclists are able to use the same section of path as pedestrians. Sidewalks have operated for at least 4000 years; the Greek city of Corinth had sidewalks by the 4th-century BCE, the Romans built sidewalks – they called them sēmitae. However, by the Middle Ages, narrow roads had reverted to being used by pedestrians and wagons without any formal separation between the two categories. Early attempts at ensuring the adequate maintenance of foot-ways or sidewalks were made, as in the 1623 Act for Colchester, although they were not effective. Following the Great Fire of London in 1666, attempts were made to bring some order to the sprawling city. In 1671,'Certain Orders and Directions Touching the Paving and Cleansing The Streets and Common Passages within the City of London' were formulated, calling for all streets to be adequately paved for pedestrians with cobblestones.
Purbeck stone was used as a durable paving material. Bollards were installed to protect pedestrians from the traffic in the middle of the road; the British House of Commons passed a series of Paving Acts from the 18th century. The 1766 Paving & Lighting Act authorized the City of London Corporation to establish foot-ways throughout all the streets of London, to pave them with Purbeck stone and to raise them above the street level with curbs forming the separation; the Corporation was made responsible for the regular upkeep of the roads, including their cleaning and repair, for which they charged a tax from 1766. By the late 19th-century large and spacious sidewalks were constructed in European capitals, were associated with urban sophistication. In the United States, adjoining property owners must in most situations finance all or part of the cost of sidewalk construction. In a legal case in 1917 involving E. L. Stewart, a former member of the Louisiana House of Representatives and a lawyer in Minden in Webster Parish, the Louisiana Supreme Court ruled that owners must pay whether they wish for the sidewalk to be constructed or not.
Sidewalks play an important role in transportation, as they provide a safe path for people to walk along, separated from the motorized traffic. They aid road safety by minimizing interaction between motorized traffic. Sidewalks are in pairs, one on each side of the road, with the center section of the road for motorized vehicles. In rural roads, sidewalks may not be present as the amount of traffic may not be enough to justify separating the two. In suburban and urban areas, sidewalks are more common. In town and city centers the amount of pedestrian traffic can exceed motorized traffic, in this case the sidewalks can occupy more than half of the width of the road, or the whole road can be reserved for pedestrians, see Pedestrian zone. Sidewalks may have a small effect on reducing carbon dioxide emissions. A study of sidewalk and transit investments in Seattle neighborhoods found vehicle travel reductions of 6 to 8% and CO2 emission reductions of 1.3 to 2.2% Research commissioned for the Florida Department of Transportation, published in 2005, found that, in Florida, the Crash Reduction Factor resulting from the installation of sidewalks averaged 74%.
Research at the University of North Carolina for the U. S. Department of Transportation found that the presence or absence of a sidewalk and the speed limit are significant factors in the likelihood of a vehicle/pedestrian crash. Sidewalk presence had a risk ratio of 0.118, which means that the likelihood of a crash on a road with a paved sidewalk was 88.2 percent lower than one without a sidewalk. “This should not be interpreted to mean that installing sidewalks would reduce the likelihood of pedestrian/motor vehicle crashes by 88.2 percent in all situations. However, the presence of a sidewalk has a strong beneficial effect of reducing the risk of a ‘walking along roadway’ pedestrian/motor vehicle crash.” The study does not count crashes. The speed limit risk ratio wa
Assemblée Nationale (Paris Métro)
Assemblée Nationale is a station on Line 12 of the Paris Métro in the 7th arrondissement, named after the nearby French National Assembly. The station opened on 5 November 1910 as part of the original section of the Nord-Sud Company's line A between Porte de Versailles and Notre-Dame-de-Lorette. On 27 March 1931 line A became line 12 of the Métro, it was called Chambre des Députés until 1989. Roland, Gérard. Stations de métro. D’Abbesses à Wagram. Éditions Bonneton
La Tour-Maubourg (Paris Métro)
La Tour-Maubourg is a station on line 8 of the Paris Métro. The station is located next to Les Invalides; the station was opened on 13 July 1913 as part of the original section of Line 8 between Beaugrenelle and Opéra. It is named after the Boulevard de la Tour-Maubourg, which commemorates Marquis Victor de Fay de la Tour-Maubourg, a General under Napoleon, Minister for War after the Restoration and Governor of Les Invalides from 1821 to 1830
Pont de l'Alma
Pont de l'Alma is a road bridge in Paris, France across the Seine. It was named to commemorate the Battle of Alma during the Crimean War, in which the Ottoman-Franco-British alliance achieved victory over the Russian army, on 20 September 1854. Construction of an arch bridge took place between 1854 and 1856, it was designed by Paul-Martin Gallocher de Lagalisserie and was inaugurated by Napoleon III on 2 April 1856. Each side of both of the two piers was decorated with a statue of military nature: a Zouave and a grenadier by Georges Diébolt, a skirmisher and an artilleryman by Arnaud; the general public took the original bridge as a measuring instrument for water levels in times of flooding on the Seine: access to the footpaths by the river embankments was closed when the Seine's level reached the feet of The Zouave. During the great flood of the Seine in 1910, the level reached his shoulders; the French Civil Service used the Pont de la Tournelle, not the Pont de l'Alma, to gauge flood levels, since 1868 uses the Pont d'Austerlitz.
The bridge underwent complete reconstruction as a girder bridge between 1970 and 1974, as it had been too narrow to accommodate the increasing traffic both on and below it. Only the statue of the Zouave was retained: the Skirmisher was relocated to the Gravelle Stronghold in Vincennes, the Grenadier to Dijon, the Artilleryman to La Fère; the bridge is close to the Pont de l'Alma tunnel where Diana, Princess of Wales and four others were involved in a fatal car crash on 31 August 1997. They were being chased by paparazzi, their chauffeur was driving under the influence of alcohol; the Flame of Liberty, at the bridge's north end has become an unofficial memorial to Diana. Pont de l'Alma has a width of 42 meters; the Metro station Alma - Marceau is near the north end of the bridge, RER station Pont de l'Alma near the south end. Pictures of the old and the new bridge Bridge history
Invalides (Paris Métro and RER)
Invalides is a Metro & RER station on lines 8 and 13 of the Paris Métro and on RER line C in the 7th arrondissement, located near and named after les Invalides. The metro station was opened on 13 July 1913 as part of the original section of Line 8 between Beaugrenelle and Opéra; the line 13 platforms were opened on 20 December 1923 as part of the original section of line 10 between Invalides and Croix Rouge. On 27 July 1937 the section of line 10 between Invalides and Duroc was transferred to become the first section of old line 14, connected under the Seine and incorporated into line 13 on 9 November 1976; the Palais Bourbon, seat of the French National Assembly, is nearby. Métro 8 Métro 13 RER C The RER station was opened on 31 May 1902 by the Chemins de fer de l'Ouest, it was a terminus but was extended to Gare d'Orsay & the line converted to RER C in 1979. List of stations of the Paris Métro List of stations of the Paris RER Invalides at Transilien, the official website of SNCF