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62-498: Anna Flyover , also known as Gemini Flyover , is a dual-armed grade separator in the central business district of Chennai , India. Built in 1973, it is the first flyover in Chennai and the third in India. It was the longest flyover in the country at its completion. It allows traffic movements on Anna Salai (formerly Mount Road) to cross traffic with grade separation. The area and the flyover

124-506: A hoist , although some pump hydraulic fluid to raise a cylindrical piston like a jack . Elevators are used in agriculture and manufacturing to lift materials. There are various types, like chain and bucket elevators , grain augers , and hay elevators . Modern buildings often have elevators to ensure accessibility, especially where ramps aren't feasible. High-speed elevators are common in skyscrapers . Some elevators can even move horizontally. The earliest known reference to an elevator

186-587: A "Chart for determining the number and size of elevators required for office buildings of a given total occupied floor area". In 1920, Howard B. Cook presented a paper titled "Passenger Elevator Service". This paper marked the first time a member of the elevator industry offered a mathematical means of determining elevator service. His formula determined the round trip time (RTT) by finding the single trip time, doubling it, and adding 10 seconds. In 1923, Bassett Jones published an article titled "The Probable Number of Stops Made by an Elevator". He based his equations on

248-535: A building is at its most busy first thing in the morning; however, in more complicated elevator systems, this model does not work. In 1990, Peters published a paper titled "Lift Traffic Analysis: Formulae for the General Case" in which he developed a new formula which would account for mixed traffic patterns as well as accounting for passenger bunching using Poisson approximation. This new General Analysis equation enabled much more complex systems to be analyzed however

310-469: A curve and fell from the flyover from a height of 20 ft. Grade separator In North America, a grade-separated junction may be referred to as a grade separation or as an interchange – in contrast with an intersection , at-grade , a diamond crossing or a level crossing , which are not grade-separated. Roads with grade separation generally allow traffic to move freely, with fewer interruptions, and at higher overall speeds; this

372-426: A deeply grooved pulley , commonly called a sheave in the industry. The weight of the car is balanced by a counterweight . Oftentimes two elevators (or sometimes three) are built so that their cars always move synchronously in opposite directions, and are each other's counterweight. The friction between the ropes and the pulley furnishes the traction which gives this type of elevator its name. Hydraulic elevators use

434-461: A floor at the same time, are usually driven by the same motor. The system increases efficiency in high-rise buildings, and saves space so additional shafts and cars are not required. In 2003, TK Elevator invented a system called TWIN, with two elevator cars independently running in one shaft. In 1901, consulting engineer Charles G. Darrach (1846–1927) proposed the first formula to determine elevator service. In 1908, Reginald P. Bolton published

496-416: A highway) that they cross. However, grade-separated pedestrian crossings with steps introduce accessibility problems. Some crossings have lifts , but these can be time-consuming to use. Grade-separated roads that permit for higher speed limits can actually reduce safety due to 'weaving' (see below) as well as a perceived sense of safety. The term is most widely applied to describe a road junction in which

558-534: A more compact system. The IGBT also allowed the development of a small, highly integrated, highly sophisticated all-digital control device, consisting of a high-speed processor, specially customized gate arrays, and a circuit capable of controlling large currents of several kHz. In 2000, the first vacuum elevator was offered commercially in Argentina. Some people argue that elevators began as simple rope or chain hoists (see Traction elevators below). An elevator

620-571: A novel tourist attraction which they called the "ascending room", which elevated customers to a considerable height in the center of London, providing a panoramic view. Early, crude steam-driven elevators were refined in the ensuing decade. In 1835, an innovative elevator, the Teagle, was developed by the company Frost and Stutt in England . It was belt-driven and used a counterweight for extra power. In 1845, Neapolitan architect Gaetano Genovese installed

682-414: A partial grade separation will accomplish more improvement than for a road), and because at-grade railway connections often take up significant space on their own. However, they require significant engineering effort, and are very expensive and time-consuming to construct. Grade-separated pedestrian and cycling routes often require modest space since they do not typically intersect with the facility (such as

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744-462: A shopping complex called Parson Manor and a 5-star deluxe hotel called The Park have been built in its place. Opposite to these across the flyover lies the Semmoli Poonga , the 20-acre, ₹ 80-million botanical garden constructed by the horticultural department. In the 1970s, over 9,000 vehicles crossed the junction during peak hour. By the 2010s, the stretch between Parry's Corner and Nandanam

806-570: A small cabinet houses the controller. The equipment is otherwise similar to that of a normal traction or hole-less hydraulic elevator. The world's first machine-room-less elevator, the Kone MonoSpace, was introduced in the year 1996, by Kone . Compared to traditional elevators, it: Its disadvantage was that it could be harder, and significantly more dangerous, to service and maintain. Double-decker elevators are traction elevators with cars that have an upper and lower deck. Both decks, which can serve

868-455: A so-called 'flying chair' built for one of his mistresses at the Château de Versailles in 1743. Ancient and medieval elevators used drive systems based on hoists and windlasses . The invention of a system based on the screw drive was perhaps the most important step in elevator technology since ancient times, leading to the creation of modern passenger elevators. The first screw-drive elevator

930-572: A successful elevator enterprise in Austria-Hungary. The safety and speed of electric elevators were significantly enhanced by Frank Sprague , who added floor control, automatic operation, acceleration control, and further safety devices. His elevator ran faster and with larger loads than hydraulic or steam elevators. 584 of Sprague's elevators were installed before he sold his company to the Otis Elevator Company in 1895. Sprague also developed

992-420: A variety of factors. Hydraulic elevators are cheaper, but installing cylinders greater than a certain length becomes impractical for very-high lift hoistways. For buildings of much over seven floors, traction elevators must be employed instead. Hydraulic elevators are usually slower than traction elevators. Elevators are a candidate for mass customization . There are economies to be made from mass production of

1054-409: A vertical cylinder, allowing the platform, carrying a heavy load, to be raised and lowered. Counterweights and balances were also used to increase lifting power. Henry Waterman of New York is credited with inventing the "standing rope control" for an elevator in 1850. In 1852, Elisha Otis introduced the safety elevator, which prevented the fall of the cab if the cable broke. He demonstrated it at

1116-426: Is applied in high-speed elevators worldwide. The Toshiba company continued research on thyristors for use in inverter control and dramatically enhanced their switching capacity, resulting in the development of insulated gate bipolar transistors (IGBTs) at the end of the 1980s. The IGBT realized increased switching frequency and reduced magnetic noise in the motor, eliminating the need for a filter circuit and allowing

1178-446: Is essentially a platform that is either pulled or pushed up by mechanical means. A modern-day elevator consists of a cab (also called a "cabin", "cage", "carriage" or "car") mounted on a platform within an enclosed space called a shaft or sometimes a "hoistway". In the past, elevator drive mechanisms were powered by steam and water hydraulic pistons or by hand. In a "traction" elevator, cars are pulled up by means of rolling steel ropes over

1240-419: Is fully grade-separated, i.e. traffic on one road does not have to stop at yield lines or signals on one road, but may have to do so when switching to the other: On roadways with grade-separated interchanges, weaving is a result of placing an exit ramp a short distance after an entry ramp, causing conflicts between traffic attempting to leave the roadway at the next junction and traffic attempting to enter from

1302-514: Is in the works of the Roman architect Vitruvius , who reported that Archimedes ( c.  287 BC – c.  212 BC ) built his first elevator probably in 236 BC. Sources from later periods mention elevators as cabs on a hemp rope, powered by people or animals. The Roman Colosseum , completed in 80 AD, had roughly 25 elevators that were used for raising animals up to the floor. Each elevator could carry about 600 pounds (270 kg) (roughly

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1364-708: Is known as a flying junction and one which is not a level junction . In 1897, the London and South Western Railway (LSWR) made use of a flying junction at Worting Junction south of Basingstoke to allow traffic on the Salisbury and Southampton routes to converge without conflicting movements; this became known as "Battledown Flyover". Also in Britain, the Southern Railway later made extensive use of flying junctions on other parts of its busy former LSWR main line. Today in Britain,

1426-575: Is named after the now-demolished Gemini Studios . On two sides of the circle roundabout below the centre of the flyover are two identical statues that commemorate the banning of horse racing in Tamil Nadu . Anna flyover was constructed in 1973 by East Coast Construction and Industries in 21 months at a cost of ₹ 6.6 million and was opened to traffic on 1 July 1973. The architects of the flyover had made provision for its extension, if necessary, on either side. Its design has remained nearly identical since

1488-571: Is thought to be the first office building with passenger elevators. In 1872, American inventor James Wayland patented a novel method of securing elevator shafts with doors that are automatically opened and closed as the elevator car approaches and leaves them. In 1874, J. W. Meaker patented a method permitting elevator doors to open and close safely. The first electric elevator was built by Werner von Siemens in 1880 in Germany. Inventor Anton Freissler further developed von Siemens' ideas and created

1550-817: Is why speed limits are typically higher for grade-separated roads. In addition, reducing the complexity of traffic movements reduces the risk of accidents . Grade-separated road junctions are typically space-intensive, complicated, and costly, due to the need for large physical structures such as tunnels, ramps, and bridges. Their height can be obtrusive, and this, combined with the large traffic volumes that grade-separated roads attract, tend to make them unpopular to nearby landowners and residents. For these reasons, proposals for new grade-separated roads can receive significant public opposition. Rail-over-rail grade separations take up less space than road grade separations: because shoulders are not needed, there are generally fewer branches and side road connections to accommodate (because

1612-514: The Great Central Railway , built between 1896 and 1899, was the first fully grade-separated railway of this type in the UK. This also applies to light rail and even to street cars . Attempts have been made to increase the capacity of railways by making tracks cross in a grade-separated manner, as opposed to the traditional use of flat crossings to change tracks. A grade-separated rail interchange

1674-476: The "Flying chair", an elevator ahead of its time in the Royal Palace of Caserta . It was covered with chestnut wood outside and with maple wood inside. It included a light, two benches, and a hand-operated signal, and could be activated from the outside, without any effort by the occupants. Traction was controlled by a motor mechanic utilizing a system of toothed wheels. A safety system was designed to take effect if

1736-579: The 1860s, subways are far more common today in Europe, especially in countries such as the Netherlands and Denmark where cycling is strongly encouraged. Long underpasses may be called tunnels . Elevator An elevator ( American English ) or lift ( Commonwealth English ) is a machine that vertically transports people or freight between levels. They are typically powered by electric motors that drive traction cables and counterweight systems such as

1798-522: The 1970s. The flyover is 500 m long. This Equestrian horse statue was sculpted by the M. N. Jayaram Nagappa son of sculptor Rao Bahadur M. S. Nagappa and brother of M. N. Mani Nagappa, who is also a sculptor. Notable landmarks abutting the Anna Flyover include the old Safire Theatre complex , the Oxford University Press and the U.S. Consulate . Gemini studio has been demolished and

1860-570: The A4/M5 junction west of Bristol . Weaving can often cause side-on collisions on very fast roads with top speeds of up to 200 kilometres per hour, as well as the problem of blind spots. Where junctions have unusual designs weaving can be a problem other than on the main road. An example of this can be found at Junction 7 of the M6, where traffic joining the roundabout from the M6 Eastbound off-slip must weave with

1922-453: The Eastbound off-slip must leave. Weaving can be alleviated by using collector/distributor roads or braided ramps to separate entering and exiting traffic. In railway construction, grade separation also means the avoidance of level crossings by making any roads or footpaths crossing the line either pass under or over the railway on bridges . This greatly improves safety and is crucial to

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1984-466: The Gemini Circle intersection costs the city ₹ 270,000 a day in petrol , human capital and ecological loss. There are plans to build a flyover on top of the existing flyover. A short-term plan at a cost of ₹ 9 million has also been planned. Anna Flyover is now maintained by Aircel Cellular as a part of corporate social responsibility, which has implemented LED lighting accentuating the parapets of

2046-569: The New York exposition in the Crystal Palace in a dramatic, death-defying presentation in 1854, and the first such passenger elevator was installed at 488 Broadway in New York City on 23 March 1857. The first elevator shaft preceded the first elevator by four years. Construction for Peter Cooper 's Cooper Union Foundation building in New York began in 1853. An elevator shaft was included in

2108-515: The capacity of a road compared to an identical road with at-grade junctions. For instance, it is extremely uncommon to find an at-grade junction on a British motorway ; it is all but impossible on a U.S. Interstate Highway , though a few do exist. If traffic can traverse the junction from any direction without being forced to come to a halt, then the junction is described as fully grade separated or free-flowing . These junctions connect two freeways: These junctions connect two roads, but only one

2170-500: The car does not reach maximum rated speed or acceleration, and added the functionality of express zones. This equation is now referred to as the 'Up peak Calculation' as it uses the assumption that all the passengers are coming into the building from the ground floor (incoming traffic) and that there are no passengers traveling from a higher floor to the ground floor (outgoing traffic) and no passengers traveling from one internal floor to another (interfloor traffic). This model works well if

2232-618: The car passed through them. The first elevator in India was installed at the Raj Bhavan in Kolkata by Otis in 1892. By 1900, completely automated elevators were available, but passengers were reluctant to use them. Their adoption was aided by a 1945 elevator operator strike in New York City, and the addition of an emergency stop button, emergency telephone, and a soothing explanatory automated voice. An inverter-controlled gearless drive system

2294-485: The components, but each building comes with its own requirements like different number of floors, dimensions of the well and usage patterns. Elevator doors prevent riders from falling into, entering, or tampering with anything in the shaft. The most common configuration is to have two panels that meet in the middle and slide open laterally. These are known as "center-opening". In a cascading telescopic configuration (potentially allowing wider entryways within limited space),

2356-458: The cords broke, consisting of a beam pushed outwards by a steel spring. The hydraulic crane was invented by Sir William Armstrong in 1846, primarily for use at the Tyneside docks for loading cargo. They quickly supplanted the earlier steam-driven elevators, exploiting Pascal's law to provide much greater force. A water pump supplied a variable level of water pressure to a plunger encased inside

2418-578: The design because Cooper was confident that a safe passenger elevator would soon be invented. The shaft was cylindrical because Cooper thought it was the most efficient design. Otis later designed a special elevator for the building. Peter Ellis , an English architect, installed the first elevators that could be described as paternoster elevators in Oriel Chambers in Liverpool in 1868. The Equitable Life Building , completed in 1870 in New York City,

2480-571: The direct flow of traffic on one or more of the roads is not disrupted. Instead of a direct connection, traffic must use on and off ramps ( United States , Australia , New Zealand ) or slip roads ( United Kingdom , Ireland ) to access the other roads at the junction. The road which carries on through the junction can also be referred to as grade separated . Typically, large freeways , highways , motorways , or dual carriageways are chosen to be grade separated, through their entire length or for part of it. Grade separation drastically increases

2542-409: The doors roll on independent tracks so that while open, they are tucked behind one another, and while closed, they form cascading layers on one side. This can be configured so that two sets of such cascading doors operate like the center opening doors described above, allowing for a very wide elevator cab. In less expensive installations the elevator can also use one large "slab" door: a single panel door

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2604-452: The elevator shaft when the car was not being entered or exited. In 1887, American inventor Alexander Miles of Duluth, Minnesota , patented an elevator with automatic doors that closed off the elevator shaft when the car was not being entered or exited. In 1891, American inventors Joseph Kelly and William L. Woods co-patented a novel way to guard elevator shafts against accident, by way of hatches that would automatically open and close as

2666-482: The equations had now become so complex that it was almost impossible to do manually and it became necessary to use software to run the calculations. The GA formula was extended even further in 1996 to account for double deck elevators. RTT calculations establish an elevator system's handling capacity by using a set of repeatable calculations which, for a given set of inputs, always produce the same answer. It works well for simple systems; but as systems get more complex,

2728-613: The faster speed requires grade separation. Therefore, many high speed lines are elevated, especially in Taiwan and Japan , where population density alongside high speed lines is higher than in France, Italy or Germany. In the United States, a flying junction on the Nickel Plate Road through Cleveland , Ohio , United States was completed in 1913. The most frequent use was later found on

2790-491: The first book devoted to this subject, Elevator Service . The summation of his work was a massive fold-out chart (placed at the back of his book) that allowed users to determine the number of express and local elevators needed for a given building to meet a desired interval of service. In 1912, commercial engineer Edmund F. Tweedy and electrical engineer Arthur Williams co-authored a book titled Commercial Engineering for Central Stations . He followed Bolton's lead and developed

2852-509: The flyover. LED lighting to beautify a public structure has been implemented for the first time in India by city-based Abra Media Networks; TNRIDC, a division of Highways, has awarded the contract to Aircel starting from July 2010. In January 1998, a small bomb was detonated under the flyover near the American consulate building. On 27 June 2012, over 40 people were injured when a Metropolitan Transport Corporation bus overturned while negotiating

2914-500: The former Pennsylvania Railroad main lines. The lines are included as part of the Northeast Corridor and Keystone Corridor now owned by Amtrak . The most complex of these junctions, near Philadelphia Zoo , handles railway traffic for Amtrak, SEPTA , New Jersey Transit , Norfolk Southern , CSX Transportation , and Conrail . In what is known as "area 1520" , which includes the former Soviet Union and other regions using

2976-802: The idea and technology for multiple elevators in a single shaft. In 1871, when hydraulic power was a well established technology, Edward B. Ellington founded Wharves and Warehouses Steam Power and Hydraulic Pressure Company, which became the London Hydraulic Power Company in 1883. It constructed a network of high-pressure mains on both sides of the Thames which ultimately extended 184 miles (296 km) and powered some 8,000 machines, predominantly elevators and cranes. Schuyler Wheeler patented his electric elevator design in 1883. In 1884, American inventor D. Humphreys of Norfolk, Virginia , patented an elevator with automatic doors that closed off

3038-409: The introduction of steel beam construction, worked together to provide the passenger and freight elevators in use today. Starting in coal mines, elevators in the mid-19th century operated with steam power , and were used for moving goods in bulk in mines and factories. These devices were soon applied to a diverse set of purposes. In 1823, Burton and Homer, two architects in London , built and operated

3100-536: The previous junction. This situation is most prevalent either where the junction designer has placed the on-slip to the road before the off-slip at a junction (for example, the cloverleaf interchange ), or in urban areas with many close-spaced junctions. The ring road of Coventry , England , is a notorious example, as are parts of the southern M25, the London orbital motorway , the M6/M5 junction north-west of Birmingham , and

3162-457: The principles of hydraulics (in the sense of hydraulic power ) to pressurize an above-ground or in-ground piston to raise and lower the car (see Hydraulic elevators below). Roped hydraulics use a combination of both ropes and hydraulic power to raise and lower cars. Recent innovations include permanent magnet motors, machine room-less rail mounted gearless machines, and microprocessor controls. The technology used in new installations depends on

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3224-540: The safe operation of high-speed lines. The construction of new level crossings is generally not permitted, especially for high speed railway lines and level crossings are increasingly less common due to the increase of both road and rail traffic. Efforts to remove level crossings are done in the UK by Network Rail and in Melbourne as part of the Level Crossing Removal Project . The London Extension of

3286-665: The same gauge, the most complicated grade-separation railpoint is found at Liubotyn in Ukraine . Footbridges and subways (called underpasses in North America as well as in the United Kingdom when referring to roads) may be employed to allow pedestrians and cyclists to cross busy or fast streets. They are often used over and under motorways since at grade pedestrian crossings are generally not permitted. Same can be said for railways. Though introduced to Central Park in New York City in

3348-412: The theory of probabilities and found a reasonably accurate method of calculating the average stop count. The equation in this article assumed a consistent population on every floor. He went on to write an updated version of his equations in 1926 which accounted for variable population on each floor. Jones credited David Lindquist for the development of the equation but provides no indication as to when it

3410-400: The tightly grouped nest of flying junctions to the north of Clapham Junction railway station —although technically a combination of many junctions—handle more than 4,000 trains per day (about one train every 15 seconds). Virtually all major railway lines no longer cross (forming an 'X' shape ) at flat level (although many diverge - i.e. 'Y' shape). On almost all high-speed railway lines,

3472-537: The traffic already on the roundabout wishing to use the M6 Westbound on-slip. This is as a result of the slip roads on the west side of the junction connecting to the roundabout on the inside of the eastern arc rather than the outside of the western arc as is normal. The two slip-roads are connected by a single lane on the inside of the roundabout, which traffic wishing to use the Westbound on-slip must join, and traffic from

3534-501: The weight of two lions) 23 feet (7.0 m) up when powered by up to eight men. In 1000, the Book of Secrets by Ibn Khalaf al-Muradi in Islamic Spain described the use of an elevator-like lifting device to raise a large battering ram to destroy a fortress. In the 17th century, prototypes of elevators were installed in the palace buildings of England and France. Louis XV of France had

3596-403: The width of the doorway that opens to the left or right laterally. These are known as "single slide" doors. Some buildings have elevators with the single door on the shaftway, and double cascading doors on the cab. Elevators that do not require separate machine rooms are designed so that most of their power and control components fit within the hoistway (the shaft containing the elevator car), and

3658-540: Was built by Ivan Kulibin and installed in the Winter Palace in 1793, although there may have been an earlier design by Leonardo da Vinci . Several years later, another of Kulibin's elevators was installed in the Arkhangelskoye near Moscow . The development of elevators was led by the need for movement of raw materials, including coal and lumber , from hillsides. The technology developed by these industries, and

3720-448: Was first proposed. Although the equations were there, elevator traffic analysis was still a very specialist task that could only be done by world experts. That was until 1967 when Strakosch wrote an eight step method for finding the efficiency of a system in "Vertical transportation: Elevators and Escalators". In 1975, Barney and Dos Santos developed and published the "Round Trip Time (RTT) formula", which followed Strakosch's work. This

3782-492: Was the first formulized mathematical model and is the simplest form that is still used by traffic analyzers today. Modification and improvements have been made to this equation over the years, most significantly in 2000 when Peters published "Improvements to the Up Peak Round Trip Time Calculation" which improved the accuracy of the flight time calculation, making allowances for short elevator journeys when

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3844-490: Was used by over 16,000 vehicles during rush hour. Anna Salai is used by over 0.183 million vehicles every day. An average of 20,000 vehicles per hour pass through the intersection beneath the flyover. The government had plans to lease out the area under the flyover to a restaurant, a shopping centre, godowns and a parking lot, and for advertising. A preliminary study by Chennai City Connect, an NGO working on improving traffic and transport conditions in Chennai, found that

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