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80-600: The original wooden and concrete trestle was opened on January 15, 1936, carrying both directions of traffic and including a drawbridge over the Snohomish River. It replaced an earlier bridge that was later removed. A parallel trestle to carry westbound traffic was partially opened on April 8, 1968, and fully opened with ceremonies on April 8, 1969, at a cost of $ 7.3 million. The trestle was converted into an expressway terminating at interchange with Interstate 5 and State Route 204. The wooden trestle had deteriorated by

160-600: A bridge-restaurant which is a bridge built to serve as a restaurant. Other suspension bridge towers carry transmission antennas. Conservationists use wildlife overpasses to reduce habitat fragmentation and animal-vehicle collisions. The first animal bridges sprung up in France in the 1950s, and these types of bridges are now used worldwide to protect both large and small wildlife. Bridges are subject to unplanned uses as well. The areas underneath some bridges have become makeshift shelters and homes to homeless people, and

240-456: A 50% decrease in accidents. It is reported that the Danes have also found that separate cycle tracks lead to a reduction in rural collisions. In some countries, the use of shoulders is optional for cyclists, who may choose not to use it for reasons such as: it being too narrow, inviting dangerously close passes at high speed by motorists; it having a road surface unsuitable for cycling or putting

320-525: A bridge is to be designed, standards authorities specify simplified notional load models, notably HL-93, intended to give the same load effects as the characteristic maximum values. The Eurocode is an example of a standard for bridge traffic loading that was developed in this way. Most bridge standards are only applicable for short and medium spans - for example, the Eurocode is only applicable for loaded lengths up to 200 m. Longer spans are dealt with on

400-471: A case-by-case basis. It is generally accepted that the intensity of load reduces as span increases because the probability of many trucks being closely spaced and extremely heavy reduces as the number of trucks involved increases. It is also generally assumed that short spans are governed by a small number of trucks traveling at high speed, with an allowance for dynamics. Longer spans on the other hand, are governed by congested traffic and no allowance for dynamics

480-480: A combination of structural health monitoring and testing. This is regulated in country-specific engineer standards and includes an ongoing monitoring every three to six months, a simple test or inspection every two to three years and a major inspection every six to ten years. In Europe, the cost of maintenance is considerable and is higher in some countries than spending on new bridges. The lifetime of welded steel bridges can be significantly extended by aftertreatment of

560-488: A controlled variable speed limit have been put in place to improve safety. This has proved very successful, with journey times decreasing by 26% northbound and 9% southbound. Drivers can also better predict their journey times as the variability decreased by 27%. The average accident rate dropped from 5.2 to 1.5 per month. It has also proved popular with motorists, 60% of whom want to see it expanded to other English motorways. This ' smart motorway ' system has been expanded to

640-399: A different site, and re-used. They are important in military engineering and are also used to carry traffic while an old bridge is being rebuilt. Movable bridges are designed to move out of the way of boats or other kinds of traffic, which would otherwise be too tall to fit. These are generally electrically powered. The Tank bridge transporter (TBT) has the same cross-country performance as

720-422: A dozen case fatalities still under coronial investigation) that had been reported to Australian coroners where a person was "struck in an emergency lane after their vehicle had stopped" between July 2000 and November 2010. The right-hand shoulder is separated by a solid white line, and the left-hand shoulder (if the road is one-way, such as part of a divided highway ) is separated from the leftmost through lane by

800-606: A few will predominate. The separation of forces and moments may be quite clear. In a suspension or cable-stayed bridge , the elements in tension are distinct in shape and placement. In other cases the forces may be distributed among a large number of members, as in a truss. The world's longest beam bridge is Lake Pontchartrain Causeway in southern Louisiana in the United States, at 23.83 miles (38.35 km), with individual spans of 56 feet (17 m). Beam bridges are

880-581: A form of boardwalk across marshes ; examples of such bridges include the Sweet Track and the Post Track in England, approximately 6000 years old. Ancient people would also have used log bridges consisting of logs that fell naturally or were intentionally felled or placed across streams. Some of the first human-made bridges with significant span were probably intentionally felled trees. Among

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960-666: A former network of roads, designed to accommodate chariots , between the fort of Tiryns and town of Epidauros in the Peloponnese , in southern Greece . Dating to the Greek Bronze Age (13th century BC), it is one of the oldest arch bridges still in existence and use. Several intact, arched stone bridges from the Hellenistic era can be found in the Peloponnese. The greatest bridge builders of antiquity were

1040-857: A pilot project that aims to reduce delayed bus trips. There are also some bus-bypass shoulders in the United Kingdom , on the motorways of Northern Ireland heading towards Belfast and the M90 motorway in Scotland towards Edinburgh . In the United Kingdom, usage of the hard shoulder is known as "hard shoulder running". A pilot project on an 18-kilometre (11 mi) stretch of the M42 motorway , near Birmingham , began in September 2006. Active traffic management with special signage, new laybys and

1120-451: A running lane, named all lane running smart motorways) and there are a small number of dual carriageway A-roads which do possess hard shoulders (for example, parts of the A1 , A2 and A27 ). Hard shoulders are always marked with a reflecting solid white line which is 20 centimetres (7.9 in) wide and is provided with a rumble strip . A line of red cats' eyes is also used, and is placed to

1200-528: A solid yellow line. On many roads, the lines are supplemented by reflective raised pavement markers or rumble strips to provide additional visual and tactile feedback to drivers crossing the lines. On freeways in foggy areas of California , there is an obvious break in the line of the shoulder before every exit. This is to help drivers find their exits in heavy fog (especially the dangerous tule fog ). In France, roadway shoulders are usually 2.5 metres (8.2 ft) wide, or 3 metres (10 ft) wide when

1280-593: A span of 552 m (1,811 ft). The bridge was opened 29 April 2009, in Chongqing , China. The longest suspension bridge in the world is the 4,608 m (15,118 ft) 1915 Çanakkale Bridge in Turkey. The longest cable-stayed bridge since 2012 is the 1,104 m (3,622 ft) Russky Bridge in Vladivostok , Russia. Some Engineers sub-divide 'beam' bridges into slab, beam-and-slab and box girder on

1360-749: A stream. Often in palaces, a bridge will be built over an artificial waterway as symbolic of a passage to an important place or state of mind. A set of five bridges cross a sinuous waterway in an important courtyard of the Forbidden City in Beijing, China. The central bridge was reserved exclusively for the use of the Emperor and Empress, with their attendants. The estimated life of bridges varies between 25 and 80 years depending on location and material. Bridges may age hundred years with proper maintenance and rehabilitation. Bridge maintenance consisting of

1440-489: A tank even when fully loaded. It can deploy, drop off and load bridges independently, but it cannot recover them. Double-decked (or double-decker) bridges have two levels, such as the George Washington Bridge , connecting New York City to Bergen County , New Jersey , US, as the world's busiest bridge, carrying 102 million vehicles annually; truss work between the roadway levels provided stiffness to

1520-420: Is 3.7 metres (12 ft). As a result, some motorists are unable to fully exit the mainline when they need to pull over, so they end up in a position that is halfway in the rightmost lane and only partly on the shoulder. The end result is often a traffic jam and occasionally a collision. In some jurisdictions in the United States and Canada, buses are allowed to drive on the shoulder to pass traffic jams, which

1600-403: Is a stub . You can help Misplaced Pages by expanding it . Shoulder (road) A shoulder ( American English ), hard shoulder ( British English ) or breakdown lane ( Australian English ) is an emergency stopping lane by the verge on the outer side of a road or motorway . Many wider freeways , or expressways elsewhere have shoulders on both sides of each directional carriageway—in

1680-462: Is a bridge that carries water, resembling a viaduct, which is a bridge that connects points of equal height. A road-rail bridge carries both road and rail traffic. Overway is a term for a bridge that separates incompatible intersecting traffic, especially road and rail. Some bridges accommodate other purposes, such as the tower of Nový Most Bridge in Bratislava , which features a restaurant, or

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1760-470: Is also historically significant as it is the world's oldest open-spandrel stone segmental arch bridge. European segmental arch bridges date back to at least the Alconétar Bridge (approximately 2nd century AD), while the enormous Roman era Trajan's Bridge (105 AD) featured open-spandrel segmental arches in wooden construction. Rope bridges , a simple type of suspension bridge , were used by

1840-588: Is an early example of a double-decked bridge. The upper level carries a railway, and the lower level is used for road traffic. Other examples include Britannia Bridge over the Menai Strait and Craigavon Bridge in Derry, Northern Ireland. The Oresund Bridge between Copenhagen and Malmö consists of a four-lane highway on the upper level and a pair of railway tracks at the lower level. Tower Bridge in London

1920-875: Is called a bus-only shoulder or bus-bypass shoulder (BBS); the term "bus-only shoulder lane" is incorrect from a technical and legal standpoint. In Ontario , Highway 403 had its shoulders between Hurontario Street and Erin Mills Parkway widened in 2003 so they serve a dual purpose as bus lanes and accident lanes. In the Minneapolis–Saint Paul region of Minnesota , over 430 kilometres (270 mi) of shoulder have been designated for use by buses. The Route 9 BBS in Central New Jersey which runs along two stretches of shoulders are dedicated for exclusive bus use during peak hours. The bus lanes, which run for approximately 4.8 kilometres (3 mi), are

2000-496: Is different example of a double-decked bridge, with the central section consisting of a low-level bascule span and a high-level footbridge . A viaduct is made up of multiple bridges connected into one longer structure. The longest and some of the highest bridges are viaducts, such as the Lake Pontchartrain Causeway and Millau Viaduct . A multi-way bridge has three or more separate spans which meet near

2080-417: Is led by architects, bridges are usually designed by engineers. This follows from the importance of the engineering requirements; namely spanning the obstacle and having the durability to survive, with minimal maintenance, in an aggressive outdoor environment. Bridges are first analysed; the bending moment and shear force distributions are calculated due to the applied loads. For this, the finite element method

2160-563: Is narrow or non-existent. To save money, the shoulder was often not paved to the same thickness as the through lanes, so if vehicles were to attempt to use it as a through lane regularly, it would rapidly deteriorate. In Britain, shoulder running can occur during roadworks, and full depth construction is now standard. In some metro areas, road authorities also allow shoulders to be used as lanes at peak periods. However, rural shoulders often collect various bits of road debris that can make driving there less safe. Drivers will sometimes drift into

2240-540: Is needed. Calculating the loading due to congested traffic remains a challenge as there is a paucity of data on inter-vehicle gaps, both within-lane and inter-lane, in congested conditions. Weigh-in-Motion (WIM) systems provide data on inter-vehicle gaps but only operate well in free flowing traffic conditions. Some authors have used cameras to measure gaps and vehicle lengths in jammed situations and have inferred weights from lengths using WIM data. Others have used microsimulation to generate typical clusters of vehicles on

2320-491: Is not allowed to drive on the shoulder, but in case of traffic blockage, use of the shoulder is allowed to reach an exit if it is within 500 metres. Full width hard shoulders are usually provided only on motorways and are usually 3.3 metres (11 ft) wide, but there are exceptions. Some motorways do not have hard shoulders at all (for example the A57(M) and many smart motorways where the hard shoulder has been converted into

2400-737: Is the most popular. The analysis can be one-, two-, or three-dimensional. For the majority of bridges, a two-dimensional plate model (often with stiffening beams) is sufficient or an upstand finite element model. On completion of the analysis, the bridge is designed to resist the applied bending moments and shear forces, section sizes are selected with sufficient capacity to resist the stresses. Many bridges are made of prestressed concrete which has good durability properties, either by pre-tensioning of beams prior to installation or post-tensioning on site. In most countries, bridges, like other structures, are designed according to Load and Resistance Factor Design (LRFD) principles. In simple terms, this means that

2480-402: Is to build a continuous paved shoulder whenever possible. The US Federal Highway Administration encourages the placement of a Safety Edge —a 30° compacted taper on the end of the pavement drop-off—to ensure that any driver running off the edge of the roadway is better able to maintain control while trying to steer back onto the roadway. The Safety Edge is effective on roads where the shoulder

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2560-510: The Inca civilization in the Andes mountains of South America, just prior to European colonization in the 16th century. The Ashanti built bridges over streams and rivers . They were constructed by pounding four large forked tree trunks into the stream bed, placing beams along these forked pillars, then positioning cross-beams that were finally covered with four to six inches of dirt. During

2640-664: The M6 , M1 and M25 , as well as parts of the M60 and M62 . In the United States, on Interstate 93 between Exit 35 (formerly 41) and Exit 43 (formerly 46) and SR 3 between Exit 27 (formerly 12) and Exit 38 (formerly 16) in the Boston metro area, cars are allowed to use the shoulder as they would a normal lane during morning and evening rush hours . The same scheme is employed elsewhere, such as on Interstate 580 in California on

2720-464: The N7 Naas Road , and such use of actual hard shoulder is not universal. The shoulders located on the sides of Italy 's highways are normally used as emergency lanes in case of breakdown or by emergency vehicles in case of queues. According to the regulation in force, it is mandatory to wear a high visibility jacket when dismounting from a vehicle stopped in an emergency lane. Normally one

2800-579: The OECD indicates that rural locations account for 35% or more of cycling fatalities in Denmark, Finland, France, Great Britain, Japan, the Netherlands, and Spain. The use of appropriately designed segregated space on arterial or interurban routes appears to be associated with reductions in overall risk. In Ireland , the provision of hard shoulders on interurban routes in the 1970s reportedly resulted in

2880-881: The Richmond-San Rafael Bridge , and on Interstate 405 between SR 527 and I-5 in Bothell . Florida has developed a plan for the use of inside shoulders by moving traffic during hurricane evacuations on portions of Interstate 4 (eastbound from Tampa to Celebration), Interstate 10 (westbound from Jacksonville to Tallahassee), Interstate 75 (northbound from Naples to I-10; both directions from Naples to Ft. Lauderdale), Interstate 95 (northbound from West Palm Beach to near Jacksonville), Florida's Turnpike (northbound from Boynton Beach to Kissimmee and Winter Garden to I-75), and Florida State Road 528 (westbound through rural Orange County). Florida's ESU plan prohibits trucks, busses, and trailers from driving on

2960-552: The Roman era , as the technology for cement was lost (then later rediscovered). In India, the Arthashastra treatise by Kautilya mentions the construction of dams and bridges. A Mauryan bridge near Girnar was surveyed by James Princep . The bridge was swept away during a flood, and later repaired by Puspagupta, the chief architect of emperor Chandragupta I . The use of stronger bridges using plaited bamboo and iron chain

3040-864: The University of Minnesota ). Likewise, in Toronto , the Prince Edward Viaduct has five lanes of motor traffic, bicycle lanes, and sidewalks on its upper deck; and a pair of tracks for the Bloor–Danforth subway line on its lower deck. The western span of the San Francisco–Oakland Bay Bridge also has two levels. Robert Stephenson 's High Level Bridge across the River Tyne in Newcastle upon Tyne , completed in 1849,

3120-608: The ancient Romans . The Romans built arch bridges and aqueducts that could stand in conditions that would damage or destroy earlier designs, some of which still stand today. An example is the Alcántara Bridge , built over the river Tagus , in Spain. The Romans also used cement, which reduced the variation of strength found in natural stone. One type of cement, called pozzolana , consisted of water, lime , sand, and volcanic rock . Brick and mortar bridges were built after

3200-504: The river Severn . With the Industrial Revolution in the 19th century, truss systems of wrought iron were developed for larger bridges, but iron does not have the tensile strength to support large loads. With the advent of steel, which has a high tensile strength, much larger bridges were built, many using the ideas of Gustave Eiffel . In Canada and the United States, numerous timber covered bridges were built in

3280-523: The 18th century, there were many innovations in the design of timber bridges by Hans Ulrich Grubenmann , Johannes Grubenmann , as well as others. The first book on bridge engineering was written by Hubert Gautier in 1716. A major breakthrough in bridge technology came with the erection of the Iron Bridge in Shropshire, England in 1779. It used cast iron for the first time as arches to cross

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3360-422: The 1970s reportedly resulted in a 50% decrease in accidents involving pedal cyclists. The hard shoulder is usually demarcated by road markings in the form of a single dashed yellow line with the addition of yellow cat's eyes . On motorways, and at critical points on other routes (e.g. between junctions or interchanges, or beneath overpasses) a solid yellow line is used, denoting additional restrictions on usage of

3440-402: The 1980s and necessitated a replacement. The narrow lane configuration and lack of a shoulder caused drivers to have anxiety attacks and contributed to hazardous driving conditions. A new 2.5-mile (4.0 km) eastbound trestle was built between 1991 and 2001 for $ 100 million, using reinforced concrete. A Washington State Transportation Commission report in 2018 listed replacement plans for

3520-465: The Tampa Bay and Sarasota-Bradenton areas. Texas has also considered emergency shoulder use for hurricane evacuations. Although direct rear impacts only make up 3% of motorist-on-cyclist collisions, they are a more prominent collision type in arterial road type situations. When they occur in such circumstances, they are also associated with significantly increased risk of fatality. Data collated by

3600-624: The appearance of the bridge can have great importance. Often, this is the case with a large bridge that serves as an entrance to a city, or crosses over a main harbor entrance. These are sometimes known as signature bridges. Designers of bridges in parks and along parkways often place more importance on aesthetics, as well. Examples include the stone-faced bridges along the Taconic State Parkway in New York. Bridges are typically more aesthetically pleasing if they are simple in shape,

3680-643: The attention of the general public in the 1990s by the novel, movie and play The Bridges of Madison County . In 1927, welding pioneer Stefan Bryła designed the first welded road bridge in the world, the Maurzyce Bridge which was later built across the river Słudwia at Maurzyce near Łowicz , Poland in 1929. In 1995, the American Welding Society presented the Historic Welded Structure Award for

3760-596: The basis of their cross-section. A slab can be solid or voided (though this is no longer favored for inspectability reasons) while beam-and-slab consists of concrete or steel girders connected by a concrete slab. A box-girder cross-section consists of a single-cell or multi-cellular box. In recent years, integral bridge construction has also become popular. Most bridges are fixed bridges, meaning they have no moving parts and stay in one place until they fail or are demolished. Temporary bridges, such as Bailey bridges , are designed to be assembled, taken apart, transported to

3840-437: The bridge to Poland. Bridges can be categorized in several different ways. Common categories include the type of structural elements used, by what they carry, whether they are fixed or movable, and by the materials used. Bridges may be classified by how the actions of tension , compression , bending , torsion and shear are distributed through their structure. Most bridges will employ all of these to some degree, but only

3920-439: The center of the bridge. Multi-way bridges with only three spans appear as a "T" or "Y" when viewed from above. Multi-way bridges are extremely rare. The Tridge , Margaret Bridge , and Zanesville Y-Bridge are examples. A bridge can be categorized by what it is designed to carry, such as trains, pedestrian or road traffic ( road bridge ), a pipeline ( Pipe bridge ) or waterway for water transport or barge traffic. An aqueduct

4000-467: The deck is thinner in proportion to its span, the lines of the structure are continuous, and the shapes of the structural elements reflect the forces acting on them. To create a beautiful image, some bridges are built much taller than necessary. This type, often found in east-Asian style gardens, is called a Moon bridge , evoking a rising full moon. Other garden bridges may cross only a dry bed of stream-washed pebbles, intended only to convey an impression of

4080-647: The edge line becomes solid. Full-width hard shoulders are provided on most new, upgraded (from the 1980s onwards), and major national roads in the Republic of Ireland , especially on wide two-lane and dual-carriageway roads (the shoulders on most 2+1 roads are narrow however). They are defined within the official document the Rules of the Road as a part of the road that should normally only be used by cyclists and pedestrians. Their provision of on interurban routes in

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4160-742: The first component of a planned 32-kilometre (20 mi) BBS corridor. In the Chicago area, Pace buses are authorised to use the shoulder of the Jane Addams Memorial Tollway , Edens Expressway , and Stevenson Expressway to avoid delays from traffic congestion. In the Seattle area, Community Transit and Sound Transit Express commuter buses are authorised to use the shoulders of Interstate 5 and Interstate 405 on small segments in Snohomish County as part of

4240-495: The hard shoulder. At junctions and on-ramps and off-ramps, the yellow line peels away into the turn, with a dashed white line (with green cats' eyes) denoting a lane division following the main route (i.e. in most cases the road remains the same width, and a turn lane takes the place of the hard shoulder). In the 2000s, Bus Éireann coaches were allowed to use the hard shoulders on national roads into Dublin. However, dedicated bus lanes are now present on sections of some routes, such as

4320-491: The lake. Between 1358 and 1360, Rudolf IV, Duke of Austria , built a 'new' wooden bridge across the lake that was used until 1878; it was approximately 1,450 metres (4,760 ft) long and 4 metres (13 ft) wide. On 6 April 2001, a reconstruction of the original wooden footbridge was opened; it is also the longest wooden bridge in Switzerland. The Arkadiko Bridge is one of four Mycenaean corbel arch bridges part of

4400-781: The late 1700s to the late 1800s, reminiscent of earlier designs in Germany and Switzerland. Some covered bridges were also built in Asia. In later years, some were partly made of stone or metal but the trusses were usually still made of wood; in the United States, there were three styles of trusses, the Queen Post, the Burr Arch and the Town Lattice. Hundreds of these structures still stand in North America. They were brought to

4480-427: The load is factored up by a factor greater than unity, while the resistance or capacity of the structure is factored down, by a factor less than unity. The effect of the factored load (stress, bending moment) should be less than the factored resistance to that effect. Both of these factors allow for uncertainty and are greater when the uncertainty is greater. Most bridges are utilitarian in appearance, but in some cases,

4560-406: The material used to make it, and the funds available to build it. The earliest bridges were likely made with fallen trees and stepping stones . The Neolithic people built boardwalk bridges across marshland. The Arkadiko Bridge , dating from the 13th century BC, in the Peloponnese is one of the oldest arch bridges in existence and use. The Oxford English Dictionary traces the origin of

4640-632: The median, as well as at the outer edges of the road, for additional safety. Shoulders are not intended for use by through traffic, although there are exceptions. Shoulders have multiple uses, including: The shoulder is usually slightly narrower than a full traffic lane. In some cases, particularly on older rural roadways, shoulders that initially existed were hardened with gravel rather than being paved with asphalt , tarmac or concrete . In Britain, motorway shoulders are now paved, but are still known as "hard shoulders". Older, gravel shoulders have sometimes been termed soft shoulders by comparison. Because

4720-639: The oldest timber bridges is the Holzbrücke Rapperswil-Hurden bridge that crossed upper Lake Zürich in Switzerland; prehistoric timber pilings discovered to the west of the Seedamm causeway date back to 1523 BC. The first wooden footbridge there led across Lake Zürich; it was reconstructed several times through the late 2nd century AD, when the Roman Empire built a 6-metre-wide (20 ft) wooden bridge to carry transport across

4800-629: The past, these load models were agreed by standard drafting committees of experts but today, this situation is changing. It is now possible to measure the components of bridge traffic load, to weigh trucks, using weigh-in-motion (WIM) technologies. With extensive WIM databases, it is possible to calculate the maximum expected load effect in the specified return period. This is an active area of research, addressing issues of opposing direction lanes, side-by-side (same direction) lanes, traffic growth, permit/non-permit vehicles and long-span bridges (see below). Rather than repeat this complex process every time

4880-414: The path of the cyclist in direct conflict with the paths of other road users, such as those turning across the shoulder. Generally, the usable width of the road begins where one can ride without increased danger of falls, jolts or blowouts. A road may have a gravel shoulder, its edge may be covered with sand or trash and the pavement may be broken. In a similar manner to Canada, Italy and the United States,

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4960-399: The paved surface ends at that point, they are less safe if they need to be used for emergency manoeuvres. Notably, the section of Ontario Highway 401 between Windsor and London had soft shoulders with a sharp slope which was blamed for facilitating vehicle rollovers, if drivers accidentally drifted off the paved section of the road and then overreacted after hitting the gravel. Modern practice

5040-457: The plan occurred on 8–9 September 2017 before the arrival of Hurricane Irma . Florida implemented ESU again in October 2024 prior to the arrival of Hurricane Milton , which underwent explosive intensification from a Category 1 into a Category 5 hurricane two days before its forecast landfall on the west central Gulf Coast of Florida as a major hurricane which prompted a large evacuation from

5120-472: The principles of Load and Resistance Factor Design . Before factoring to allow for uncertainty, the load effect is generally considered to be the maximum characteristic value in a specified return period . Notably, in Europe, it is the maximum value expected in 1000 years. Bridge standards generally include a load model, deemed to represent the characteristic maximum load to be expected in the return period. In

5200-402: The purpose of providing passage over the obstacle, which is usually something that is otherwise difficult or impossible to cross. There are many different designs of bridges, each serving a particular purpose and applicable to different situations. Designs of bridges vary depending on factors such as the function of the bridge, the nature of the terrain where the bridge is constructed and anchored,

5280-508: The roadway carries more than 2,000 vehicles per day. The main difference from other European countries is that the white line is dashed, typically 39 metres (128 ft) long with gaps 13 metres (43 ft) long. The design is intended to provide a guide for drivers to maintain a safe distance between vehicles. Road signs can be found along motorways, to indicate the safe distance (1 line = too close, 2 lines = safe distance). At some points (tunnel, bridge, narrow road with no shoulder, tight curve)

5360-763: The roadways and reduced movement of the upper level when the lower level was installed three decades after the upper level. The Tsing Ma Bridge and Kap Shui Mun Bridge in Hong Kong have six lanes on their upper decks, and on their lower decks there are two lanes and a pair of tracks for MTR metro trains. Some double-decked bridges only use one level for street traffic; the Washington Avenue Bridge in Minneapolis reserves its lower level for automobile and light rail traffic and its upper level for pedestrian and bicycle traffic (predominantly students at

5440-406: The safety benefits of the shoulder. Some roads have a narrow shoulder for significant distances. This makes it difficult for large vehicles to pull into the hard shoulder altogether. The Jingjintang Expressway in north-eastern China is an example of this phenomenon. Its shoulder is only 2.4 metres (7.9 ft) wide, which is not wide enough for some automobiles—a standard lane in the U.S. and UK

5520-734: The same year, has the span of 90 m (295 ft) and crosses the valley of the Syrabach River. The difference between the two is that the Solkan Bridge was built from stone blocks, whereas the Friedensbrücke was built from a mixture of crushed stone and cement mortar. The world's largest arch bridge is the Chaotianmen Bridge over the Yangtze River with a length of 1,741 m (5,712 ft) and

5600-452: The shoulder and limits the speed limit to 50 mph on the shoulder, which is typically only 10 feet (3.0 m) wide compared to the standard 12 feet (3.7 m) width of highway travel lanes and contains rumble strips . The shoulder-use plan was implemented in place of labour- and resource-intensive contraflow lane reversal , in which both sides of an interstate highway are used for one direction of traffic. The first implementation of

5680-424: The shoulder when being overtaken by passing vehicles, particularly on two-lane roads. However, it is extremely unsafe, and in most jurisdictions illegal, to abuse the shoulder by 'undertaking' passing vehicles that are nearer the centre of the road. On older roads, the shoulder may disappear for short periods, near exits or when going across or under bridges or tunnels where the cost savings were thought to outweigh

5760-614: The shoulders located on the side of Australia's highways are normally used as an emergency lane in the case of a breakdown or by emergency vehicles in the case of road congestion. However, no mandatory regulations exist to wear a high-visibility jacket when dismounting from the vehicle stopped in an emergency lane. A recent study conducted by the National Coroners Information System (NCIS) in Australia has revealed 29 closed case fatalities (and at least

5840-409: The side of the line. On many modern non-motorway roads, hard strips are provided. These are usually 1 metre (3.3 ft) wide, and are bounded by thinner solid white lines, and often without a rumble strip. Bridge A bridge is a structure built to span a physical obstacle (such as a body of water , valley , road, or railway) without blocking the path underneath. It is constructed for

5920-653: The simplest and oldest type of bridge in use today, and are a popular type. Some cantilever bridges also have a smaller beam connecting the two cantilevers, for extra strength. The largest cantilever bridge is the 549-metre (1,801 ft) Quebec Bridge in Quebec, Canada. With the span of 220 metres (720 ft), the Solkan Bridge over the Soča River at Solkan in Slovenia is the second-largest stone bridge in

6000-748: The undertimbers of bridges all around the world are spots of prevalent graffiti. Some bridges attract people attempting suicide, and become known as suicide bridges . The materials used to build the structure are also used to categorize bridges. Until the end of the 18th century, bridges were made out of timber, stone and masonry. Modern bridges are currently built in concrete, steel, fiber reinforced polymers (FRP), stainless steel or combinations of those materials. Living bridges have been constructed of live plants such as Ficus elastica tree roots in India and wisteria vines in Japan. Unlike buildings whose design

6080-433: The weld transitions . This results in a potential high benefit, using existing bridges far beyond the planned lifetime. While the response of a bridge to the applied loading is well understood, the applied traffic loading itself is still the subject of research. This is a statistical problem as loading is highly variable, particularly for road bridges. Load Effects in bridges (stresses, bending moments) are designed for using

6160-433: The westbound trestle with a new, three-lane trestle at costs ranging from $ 620 million to $ 2 billion with funding by various means including up to $ 690 million in tolls. The westbound trestle is a major traffic chokepoint for communities in eastern Snohomish County and is seismically vulnerable, with estimates of up to three years to replace the structure after a major earthquake. This Washington (state) road-related article

6240-481: The word bridge to an Old English word brycg , of the same meaning.   The Oxford English Dictionary also notes that there is some suggestion that the word can be traced directly back to Proto-Indo-European *bʰrēw-. However, they also note that "this poses semantic problems." The origin of the word for the card game of the same name is unknown.   The simplest and earliest types of bridges were stepping stones . Neolithic people also built

6320-452: The world and the longest railroad stone bridge. It was completed in 1905. Its arch, which was constructed from over 5,000 tonnes (4,900 long tons; 5,500 short tons) of stone blocks in just 18 days, is the second-largest stone arch in the world, surpassed only by the Friedensbrücke (Syratalviadukt) in Plauen , and the largest railroad stone arch. The arch of the Friedensbrücke, which was built in

6400-690: Was visible in India by about the 4th century. A number of bridges, both for military and commercial purposes, were constructed by the Mughal administration in India. Although large bridges of wooden construction existed in China at the time of the Warring States period , the oldest surviving stone bridge in China is the Zhaozhou Bridge , built from 595 to 605 AD during the Sui dynasty . This bridge

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