133-458: The Orange Line is a 37-mile (60 km) light rail line in the Dallas, Texas metropolitan area. The line is operated by Dallas Area Rapid Transit as a part of its DART light rail system. It is the only east-west line in the system. The line runs from Dallas Fort Worth International Airport to northeastern Dallas, passing through Irving 's Las Colinas neighborhood and Downtown Dallas in
266-542: A malacologist would still consider them to be pearls. Valueless pearls of this type are sometimes found in edible mussels , edible oysters , escargot snails, and so on. The GIA and CIBJO now simply use the term 'pearl' (or, where appropriate, the more descriptive term 'non-nacreous pearl') when referring to such items and, under Federal Trade Commission rules, various mollusk pearls may be referred to as 'pearls', without qualification. A few species produce pearls that can be of interest as gemstones. These species include
399-724: A "light rail" vehicle (it is a heavy rail vehicle), and is only included for comparison purposes. Low-floor LRVs have the advantage of a low-floor design, allowing them to load passengers directly from low-rise platforms that can be little more than raised curbs. High-floor light rail systems also exist, featuring larger stations. Historically, the track gauge has had considerable variations, with narrow gauge common in many early systems. However, most light rail systems are now standard gauge . Older standard-gauge vehicles could not negotiate sharp turns as easily as narrow-gauge ones, but modern light rail systems achieve tighter turning radii by using articulated cars . An important advantage of
532-473: A South Sea pearl – as described by CIBJO and GIA – is a pearl produced by the Pinctada maxima pearl oyster. South Sea pearls are the color of their host Pinctada maxima oyster – and can be white, silver, pink, gold, cream, and any combination of these basic colors, including overtones of the various colors of the rainbow displayed in the pearl nacre of the oyster shell itself. South Sea pearls are
665-415: A beaded cultured pearl is generally a polished sphere made from freshwater mussel shell. Along with a small piece of mantle tissue from another mollusk (donor shell) to serve as a catalyst for the pearl sac, it is surgically implanted into the gonad (reproductive organ) of a saltwater mollusk. In freshwater perliculture, only the piece of tissue is used in most cases, and is inserted into the fleshy mantle of
798-456: A body color that may be assessed as silver, silver blue, gold, brown-black, green-black, or black. Black cultured pearls from the black pearl oyster – Pinctada margaritifera – are not South Sea pearls, although they are often mistakenly described as black South Sea pearls. In the absence of an official definition for the pearl from the black all use to, these pearls are usually referred to as "black pearls". The correct definition of
931-458: A bus, there will be even more capacity when there is a combination of cars and light rail. Table 3 shows an example of peak passenger capacity. The cost of light rail construction varies widely, largely depending on the amount of tunneling and elevated structures required. A survey of North American light rail projects shows that costs of most LRT systems range from $ 15 million to over $ 100 million per mile. Seattle's new light rail system
1064-403: A chaotic breakdown inflow and a dramatic drop in speed (a traffic jam ) if they exceed about 2,000 vehicles per hour per lane (each car roughly two seconds behind another). Since most people who drive to work or on business trips do so alone, studies show that the average car occupancy on many roads carrying commuters is only about 1.5 people per car during the high-demand rush hour periods of
1197-1102: A common right-of-way (however, Link converted to full separation in 2019). Some systems, such as the AirTrain JFK in New York City, the DLR in London, and Kelana Jaya Line in Kuala Lumpur , have dispensed with the need for an operator. The Vancouver SkyTrain was an early adopter of driverless vehicles, while the Toronto Scarborough rapid transit operated the same trains as Vancouver, but used drivers. In most discussions and comparisons, these specialized systems are generally not considered light rail but as light metro systems. Around Karlsruhe , Kassel , and Saarbrücken in Germany, dual-voltage light rail trains partly use mainline railroad tracks, sharing these tracks with heavy rail trains. In
1330-630: A length of 14 miles (23 km), is the only portion of the Orange Line that is not shared with other DART light rail lines. The line's western terminus is DFW Airport Terminal A , located inside Dallas Fort Worth International Airport . The line exits the airport through the north and proceeds southeast through Irving's Las Colinas neighborhood, passing Dallas College North Lake and Irving Convention Center . The line curves around Lake Carolyn before traveling south to John Carpenter Freeway (SH 114). Turning east, it parallels SH 114, passing
1463-416: A light rail train may have three to four cars of much larger capacity in one train under the control of one driver, or no driver at all in fully automated systems, increasing the labor costs of BRT systems compared to LRT systems. BRT systems are also usually less fuel-efficient as they use non-electrified vehicles. The peak passenger capacity per lane per hour depends on which types of vehicles are allowed on
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#17328526452231596-435: A live rail. In outer areas, the trams switch to conventional overhead wires . The Bordeaux power system costs about three times as much as a conventional overhead wire system and took 24 months to achieve acceptable levels of reliability, requiring the replacement of all the main cables and power supplies. Operating and maintenance costs of the innovative power system still remain high. However, despite numerous service outages,
1729-536: A longer distance. Light rail cars are often coupled into multiple units of two to four cars. Light rail systems may also exhibit attributes of heavy rail systems, including having downtown subways, as in San Francisco and Seattle . Light rail is designed to address a gap in interurban transportation between heavy rail and bus services, carrying high passenger numbers more quickly than local buses and more cheaply than heavy rail. It serves corridors in which heavy rail
1862-631: A more diverse range of design characteristics than LRT, depending on the demand and constraints that exist, and BRT using dedicated lanes can have a theoretical capacity of over 30,000 passengers per hour per direction (for example, the Guangzhou Bus Rapid Transit system operates up to 350 buses per hour per direction). For the effective operation of a bus or BRT system, buses must have priority at traffic lights and have their dedicated lanes, especially as bus frequencies exceed 30 buses per hour per direction. The higher theoretical of BRT relates to
1995-414: A natural pearl shows a series of concentric growth rings. A beadless cultured pearl (whether of freshwater or saltwater origin) may show growth rings, but also a complex central cavity, witness of the first precipitation of the young pearl sac. Some imitation pearls (also called shell pearls) are simply made of mother-of-pearl , coral or conch shell, while others are made from glass and are coated with
2128-521: A proposed commuter rail line on the BNSF corridor that would run from Irving to Frisco . Light rail Light rail (or light rail transit , abbreviated to LRT ) is a form of passenger urban rail transit that uses rolling stock derived from tram technology while also having some features from heavy rapid transit . The term was coined in 1972 in the United States as an English equivalent for
2261-407: A result, has many of the operating characteristics of a metro system rather than a light rail system. A capacity of 1,350 passengers per train is more similar to the heavy rail than light rail. Bus rapid transit (BRT) is an alternative to LRT and many planning studies undertake a comparison of each mode when considering appropriate investments in transit corridor development. BRT systems can exhibit
2394-475: A solution containing fish scales called essence d'Orient . A well-equipped gem testing laboratory can distinguish natural pearls from cultured pearls by using gemological X-ray equipment to examine the center of a pearl. With X-rays it is possible to see the growth rings of the pearl, where the layers of calcium carbonate are separated by thin layers of conchiolin. The differentiation of natural pearls from non-beaded cultured pearls can be very difficult without
2527-450: A species of small pearl oyster, Pinctada fucata martensii , which is no bigger than 6 to 8 cm (2.4 to 3.1 in) in size, hence akoya pearls larger than 10 mm in diameter are extremely rare and highly priced. Today, a hybrid mollusk is used in both Japan and China in the production of akoya pearls. Cultured Pearls were sold in cans for the export market. These were packed in Japan by
2660-509: A spherical bead as a nucleus. Most saltwater cultured pearls are grown with beads. Trade names of cultured pearls are Akoya ( 阿古屋 ), white or golden South sea, and black Tahitian . Most beadless cultured pearls are mantle-grown in freshwater shells in China, and are known as freshwater cultured pearls. Cultured pearls can be distinguished from natural pearls by X-ray examination. Nucleated cultured pearls are often 'preformed' as they tend to follow
2793-530: A top speed of 55–71.5 miles per hour (88.51–115.1 km/h) depending on the system, while the trains on the all-underground Montreal Metro can only reach a top speed of 72 kilometres per hour (44.74 mph). LACMTA light rail vehicles have higher top and average speeds than Montreal Metro or New York City Subway trains. Many light rail systems—even fairly old ones—have a combination of both on- and off-road sections. In some countries (especially in Europe), only
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#17328526452232926-418: A tramway, a light metro, and, in a narrow sense, rapid transit. This is especially common in the United States, where there is not a popularly perceived distinction between these different types of urban rail systems. The development of technology for low-floor and catenary-free trams facilitates the construction of such mixed systems with only short and shallow underground sections below critical intersections as
3059-462: Is a generic international English phrase for types of rail systems using modern streetcars/trams, which means more or less the same thing throughout the English-speaking world . Light rail systems can range from trams runnig in streets along with other traffic, to semi-metro systems having portions of grade separated track. People movers are even "lighter", in terms of capacity. Monorail
3192-522: Is a particularly large one weighing 14 lb (6.4 kg). The largest known pearl (also from a giant clam) is the Pearl of Puerto , also found in the Philippines by a fisherman from Puerto Princesa , Palawan Island . The enormous pearl is 30 cm wide (1 ft), 67 cm long (2.2 ft) and weighs 75 lb (34 kg). The ancient chronicle Mahavamsa mentions the thriving pearl industry in
3325-565: Is a separate technology that has been more successful in specialized services than in a commuter transit role. The use of the generic term light rail avoids some serious incompatibilities between British and American English . The word tram , for instance, is generally used in the UK and many former British colonies to refer to what is known in North America as a streetcar , but in North America tram can instead refer to an aerial tramway , or, in
3458-602: Is a significant amount of overlap between the technologies; similar rolling stock may be used for either, and it is common to classify streetcars or trams as a subcategory of light rail rather than as a distinct type of transportation. However, some distinctions can be made, though systems may combine elements of both. Low-floor light rail lines tend to follow a reserved right-of-way and with trains receiving priority at intersections, and tend not to operate in mixed traffic, enabling higher operating speeds. Light rail lines tend to have less frequent stops than tramways, and operate over
3591-560: Is by far the most expensive in the US, at $ 179 million per mile, since it includes extensive tunneling in poor soil conditions, elevated sections, and stations as deep as 180 feet (55 m) below ground level. This results in costs more typical of subways or rapid transit systems than light rail. At the other end of the scale, four systems (Baltimore, Maryland; Camden, New Jersey; Sacramento, California; and Salt Lake City, Utah) incurred construction costs of less than $ 20 million per mile. Over
3724-426: Is especially important for wheelchair access, as narrower gauges (e.g. metre gauge) can make it challenging or impossible to pass the tram's wheels. Furthermore, standard-gauge rolling stock can be switched between networks either temporarily or permanently, and both newly built and used standard-gauge rolling stock tends to be cheaper to buy, as more companies offer such vehicles. Overhead lines supply electricity to
3857-498: Is expensive. Similarly, the most expensive US highway expansion project was the " Big Dig " in Boston, Massachusetts, which cost $ 200 million per lane mile for a total cost of $ 14.6 billion. A light rail track can carry up to 20,000 people per hour as compared with 2,000–2,200 vehicles per hour for one freeway lane. For example, in Boston and San Francisco, light rail lines carry 9,600 and 13,100 passengers per hour, respectively, in
3990-459: Is grown at a time. This limits the number of pearls at a harvest period. The pearls are usually harvested after one year for akoya, 2–4 years for Tahitian and South Sea, and 2–7 years for freshwater. This perliculture process was first developed by the British biologist William Saville-Kent who passed the information along to Tatsuhei Mise and Tokichi Nishikawa from Japan . The second category includes
4123-575: Is hard to distinguish between what is called light rail, and other forms of urban and commuter rail. A system described as a light rail in one city may be considered to be a streetcar or tram system in another. Conversely, some lines that are called "light rail" are very similar to rapid transit ; in recent years, new terms such as light metro have been used to describe these medium-capacity systems. Some "light rail" systems, such as Sprinter , bear little similarity to urban rail, and could alternatively be classified as commuter rail or even inter-city rail. In
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4256-549: Is impractical. Light metro systems are essentially hybrids of light rail and rapid transit. Metro trains are larger and faster than light rail trains, with stops being further apart. Many systems have mixed characteristics. Indeed, with proper engineering, a rail line could run along a street, then go underground, and then run along an elevated viaduct. For example, the Los Angeles Metro Rail 's A Line "light rail" has sections that could alternatively be described as
4389-549: Is more valuable than these pearls. However, it is more abundant than the South Sea pearl, which is more valuable than the black cultured pearl. This is simply because the black pearl oyster Pinctada margaritifera is far more abundant than the elusive, rare, and larger south sea pearl oyster Pinctada maxima , which cannot be found in lagoons, but which must be dived for in a rare number of deep ocean habitats or grown in hatcheries. Natural black pearls are rare, with black pearls having
4522-480: Is one of the highest capacity ones, having been upgraded in a series of expansions to handle 40,000 passengers per hour per direction, and having carried as many as 582,989 passengers in a single day on its Line 1 . It achieves this volume by running four-car trains with a capacity of up to 1,350 passengers each at a frequency of up to 30 trains per hour. However, the Manila light rail system has full grade separation and as
4655-531: Is perfectly round and smooth, but many other shapes, known as baroque pearls , can occur. The finest quality of natural pearls have been highly valued as gemstones and objects of beauty for many centuries. Because of this, pearl has become a metaphor for something rare, fine, admirable and valuable. The most valuable pearls occur spontaneously in the wild, but are extremely rare. These wild pearls are referred to as natural pearls. Cultured or farmed pearls from pearl oysters and freshwater mussels make up
4788-415: Is required to positively verify natural pearls found today. A keshi pearl is a pearl composed entirely of nacre and results from mishaps in the culturing process. Most are quite small, typically only a few millimeters in diameter, and are often irregular in shape. In seeding a cultured pearl, a piece of mantle muscle from a sacrificed oyster is placed with a bead of mother of pearl within a host oyster. If
4921-547: Is serviced through a shuttle at Inwood/Love Field station ). When Denton Drive ends, the lines continue south through the Southwestern Medical District to Harry Hines Boulevard . They briefly follow Harry Hines to Interstate 35E , where they turn to follows I-35E to Downtown Dallas . Alongside the Green Line, the Orange Line enters Downtown Dallas at Victory Park . After stopping at American Airlines Center ,
5054-407: Is similar to that of a traditional tram, while operating at a higher capacity and speed, often on an exclusive right-of-way. In broader use, it includes tram-like operations mostly on streets. A few light rail networks have characteristics closer to rapid transit or even commuter rail , yet only when these systems are fully grade-separated are they referred to as light metros . The term light rail
5187-925: Is susceptible to even a weak acid solution because the crystals react with the acetic acid in the vinegar to form calcium acetate and carbon dioxide . Freshwater and saltwater pearls may sometimes look quite similar, but they come from different sources. Freshwater pearls form in various species of freshwater mussels, family Unionidae , which live in lakes, rivers, ponds and other bodies of fresh water. These freshwater pearl mussels occur not only in hotter climates, but also in colder, more temperate areas such as Scotland (where they are protected under law). Most freshwater cultured pearls sold today come from China. Saltwater pearls grow within pearl oysters, family Pteriidae , which live in oceans. Saltwater pearl oysters are usually cultivated in protected lagoons or volcanic atolls. The mollusk's mantle (protective membrane) deposits layers of calcium carbonate (CaCO 3 ) in
5320-618: Is the conch pearl (sometimes referred to simply as the 'pink pearl'), which is found very rarely growing between the mantle and the shell of the queen conch or pink conch, Strombus gigas , a large sea snail or marine gastropod from the Caribbean Sea . These pearls, which are often pink in color, are a by-product of the conch fishing industry, and the best of them display a shimmering optical effect related to chatoyance known as 'flame structure'. Somewhat similar gastropod pearls, this time more orange in hue, are (again very rarely) found in
5453-502: Is thought that natural pearls form under a set of accidental conditions when a microscopic intruder or parasite enters a bivalve mollusk and settles inside the shell. The mollusk, irritated by the intruder, forms a pearl sac of external mantle tissue cells and secretes the calcium carbonate and conchiolin to cover the irritant. This secretion process is repeated many times, thus producing a pearl. Natural pearls come in many shapes, with perfectly round ones being comparatively rare. Typically,
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5586-516: The Broome area of Australia, while golden colored ones are more prevalent in the Philippines and Indonesia. A farm in the Gulf of California , Mexico, is culturing pearls from the black lipped Pinctada mazatlanica oysters and the rainbow lipped Pteria sterna oysters. Also called Concha Nácar, the pearls from these rainbow lipped oysters fluoresce red under ultraviolet light. Biologically speaking, under
5719-535: The Cádiz TramBahia , where trams share track with commuter and long-distance trains from the main terminus in the city and curve off to serve cities without a railway connection. Some of the issues involved in such schemes are: There is a history of what would now be considered light rail vehicles operating on heavy rail rapid transit tracks in the US, especially in the case of interurban streetcars . Notable examples are Lehigh Valley Transit trains running on
5852-689: The French perle , originally from the Latin perna ' leg ' , after the ham- or mutton leg-shaped bivalve . The scientific name for the family of pearl-bearing oysters, Margaritiferidae comes from the Old Persian word for pearl * margārīta- which is the source of the English name Margaret . All shelled mollusks can, by natural processes, produce some kind of "pearl" when an irritating microscopic object becomes trapped within its mantle folds, but
5985-841: The Indian Ocean in areas such as the Persian Gulf , the Red Sea and the Gulf of Mannar . Evidence also suggest a prehistoric origin to pearl diving in these regions. Starting in the Han dynasty (206 BC–220 AD), the Chinese hunted extensively for seawater pearls in the South China Sea , particularly in what is now Tolo Harbour in Hong Kong . Tanka pearl divers of twelfth century China attached ropes to their waists in order to be safely brought back up to
6118-735: The London Underground and the New York City Subway . Conventional rail technologies including high-speed , freight, commuter , and rapid transit urban transit systems are considered "heavy rail". The main difference between light rail and heavy rail rapid transit is the ability for a light rail vehicle to operate in mixed traffic if the routing requires it. The world's first electric tram operated in Sestroretsk near Saint Petersburg , Russia , invented and operated on an experimental basis by Fyodor Pirotsky in 1880. The first tramway
6251-624: The Netherlands , this concept was first applied on the RijnGouweLijn . This allows commuters to ride directly into the city center, rather than taking a mainline train only as far as a central station and then having to change to a tram. In France, similar tram-trains are planned for Paris, Mulhouse , and Strasbourg ; further projects exist. In some cases, tram trains use previously abandoned or lightly used heavy rail lines in addition to or instead of still in use mainline tracks. In 2022, Spain opened
6384-831: The O-Train Trillium Line in Ottawa, Ontario , Canada, the River Line in New Jersey , United States, and the Sprinter in California , United States, which use diesel multiple unit (DMU) cars. Light rail is different from the British English term light railway , long-used to distinguish railway operations carried out under a less rigorous set of regulations using lighter equipment at lower speeds from mainline railways. Light rail
6517-463: The Parker Road station to Bachman station on stations shared with DART 's Red and Green lines. The first Orange Line-exclusive stations opened with the extension to Irving Convention Center on July 30, 2012, and two more were added on December 3, 2012. The current northwestern terminus, located at Dallas/Fort Worth International Airport , opened on August 18, 2014. Hidden Ridge Station , which
6650-673: The Philadelphia and Western Railroad high-speed third rail line (now the Norristown High-Speed Line ). Such arrangements are almost impossible now, due to the Federal Railroad Administration refusing (for crash safety reasons) to allow non-FRA compliant railcars (i.e., subway and light rail vehicles) to run on the same tracks at the same times as compliant railcars, which includes locomotives and standard railroad passenger and freight equipment. Notable exceptions in
6783-667: The University of Dallas . At the former site of Texas Stadium , the line sharply redirects northeast, paralleling Storey Lane (Spur 482) and crossing the Elm Fork of the Trinity River . Upon reaching Northwest Highway (Loop 12), it curves southeast and merges with the Green Line , where it proceeds to Bachman station . Alongside the Green Line, the Orange Line travels southeast along Denton Drive, passing Dallas Love Field (which
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#17328526452236916-403: The freshwater pearl mussel . Saltwater pearls can grow in several species of marine pearl oysters in the family Pteriidae . Freshwater pearls grow within certain (but by no means all) species of freshwater mussels in the order Unionida, the families Unionidae and Margaritiferidae . The unique luster of pearls depends upon the reflection , refraction , and diffraction of light from
7049-530: The medians of roads . If run in streets , trains are usually limited by city block lengths to about four 180-passenger vehicles (720 passengers). Operating on two-minute headways using traffic signal progression, a well-designed two-track system can handle up to 30 trains per hour per track, achieving peak rates of over 20,000 passengers per hour in each direction. More advanced systems with separate rights-of-way using moving block signaling can exceed 25,000 passengers per hour per track. Most light rail systems in
7182-543: The translucent layers. The thinner and more numerous the layers in the pearl, the finer the luster. The iridescence that pearls display is caused by the overlapping of successive layers, which breaks up light falling on the surface. In addition, pearls (especially cultured freshwater pearls ) can be dyed yellow, green, blue, brown, pink, purple, or black. The most valuable pearls have a metallic, highly reflective luster. Because pearls are made primarily of calcium carbonate, they can be dissolved in vinegar . Calcium carbonate
7315-619: The 1970s was proven to have been a technical failure by the following decade. After World War II, the Germans retained many of their streetcar networks and evolved them into model light rail systems ( Stadtbahnen ). With the exception of Hamburg , all large and most medium-sized German cities maintain light rail networks. The concept of a "limited tramway" was proposed by American transport planner H. Dean Quinby in 1962. Quinby distinguished this new concept in rail transportation from historic streetcar or tram systems as: The term light rail transit
7448-576: The Fifth Avenue mansion that is now the New York Cartier store in exchange for a matched double strand of natural pearls Cartier had been collecting for years; at the time, it was valued at US$ 1 million.) The introduction and advance of the cultured pearl hit the pearl industry hard. Pearl dealers publicly disputed the authenticity of these new cultured products, and left many consumers uneasy and confused about their much lower prices. Essentially,
7581-491: The French city of Bordeaux , the tramway network is powered by a third rail in the city center, where the tracks are not always segregated from pedestrians and cars. The third rail (actually two closely spaced rails) is placed in the middle of the track and divided into eight-metre sections, each of which is powered only while it is completely covered by a tram. This minimizes the risk of a person or animal coming into contact with
7714-482: The German word Stadtbahn , meaning "city railway". Different definitions exist in some countries, but in the United States, light rail operates primarily along exclusive rights-of-way and uses either individual tramcars or multiple units coupled together, with a lower capacity and speed than a long heavy rail passenger train or rapid transit system. Narrowly defined, light rail transit uses rolling stock that
7847-519: The King found it so beautiful that he kept it for himself. Later, he elevated it to be part of the Spanish Crown Jewel. From then on, the pearl was recorded in every royal inventory for more than 200 years. According to Garcilasso de la Vega , who says that he saw La Peregrina at Seville in 1607, this was found at Panama in 1560 by a slave worker who was rewarded with his liberty, and his owner with
7980-705: The Northwest Rail Operating Facility terminate at Bachman station , which is directly south of the yard. Trains entering or leaving the Central Rail Operating Facility will divert from Pearl/Arts District to the southern Green Line , stopping at Deep Ellum and Baylor University Medical Center before terminating at Fair Park . Light rail transit in the Las Colinas area was first studied in 2000 as part of DART's Northwest Corridor study. The study proposed two lines, which evolved into
8113-451: The Orange Line and Red Line continue to parallel US 75 until the corridor's terminus at Parker Road station . During non-peak hours, the line terminates at LBJ/Central station , just south of Interstate 635 . A pocket track north of I-635 is used to move trains from eastbound to westbound service. When individual trains are entering or exiting service, special termini near DART's two rail yards are used. Trains entering or leaving
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#17328526452238246-589: The Orange Line between DFW Airport Terminal A and Belt Line . However, by the time the Corridor was approved in 2018, expansions to SH-114 and SH-121 rendered this extension infeasible. Instead, the Silver Line was extended south to DFW Airport Terminal B by sharing tracks with TEXRail . The D2 Subway project would reroute the line's Downtown Dallas segment into a new subway tunnel between Victory and Deep Ellum with four new underground stations. The project
8379-487: The Orange Line turns east onto Pacific Avenue, which it shares with all other DART lines. It follows Pacific Avenue, and later Bryan Street, to the east side of downtown. Along with the Red Line and Blue Line , the Orange Line turns north into a subway tunnel paralleling North Central Expressway (US 75). After passing the underground Cityplace/Uptown station , the subway tunnel ends at Mockingbird Lane . Above ground,
8512-642: The US are the NJ Transit River Line from Camden to Trenton and Austin's Capital MetroRail , which have received exemptions to the provision that light rail operations occur only during daytime hours and Conrail freight service only at night, with several hours separating one operation from the other. The O-Train Trillium Line in Ottawa also has freight service at certain hours. With its mix of right-of-way types and train control technologies, LRT offers
8645-455: The US as a whole, excluding Seattle, new light rail construction costs average about $ 35 million per mile. By comparison, a freeway lane expansion typically costs $ 1.0 million to $ 8.5 million per lane mile for two directions, with an average of $ 2.3 million. However, freeways are frequently built in suburbs or rural areas, whereas light rail tends to be concentrated in urban areas, where right of way and property acquisition
8778-634: The United States and in North America . In Britain, modern light rail systems began to appear in the 1980s, starting with the Tyne and Wear Metro from 1980 and followed by the Docklands Light Railway (DLR) in London in 1987, continuing into the 1990s including the establishment of the Manchester Metrolink in 1992 and the Sheffield Supertram from 1994. Due to varying definitions, it
8911-583: The United States are limited by demand rather than capacity (by and large, most American LRT systems carry fewer than 4,000 persons per hour per direction), but Boston's and San Francisco's light rail lines carry 9,600 and 13,100 passengers per hour per track during rush hour. Elsewhere in North America, the Calgary C-Train and Monterrey Metro have higher light rail ridership than Boston or San Francisco. Systems outside North America often have much higher passenger volumes. The Manila Light Rail Transit System
9044-472: The United States, "light rail" has become a catch-all term to describe a wide variety of passenger rail systems. Light rail corridors may constitute a fully segregated corridor, a dedicated right-of-way on a street, an on-street corridor shared with other traffic, a corridor shared with other public transport, or a corridor shared with pedestrians. The most difficult distinction to draw is that between low-floor light rail and streetcar or tram systems. There
9177-415: The ability of buses to travel closer to each other than rail vehicles and their ability to overtake each other at designated locations allowing express services to bypass those that have stopped at stations. However, to achieve capacities this high, BRT station footprints need to be significantly larger than a typical LRT station. In terms of cost of operation, each bus vehicle requires a single driver, whereas
9310-449: The agency said that due to cost savings and federal funds, the plans for the line have been revived. On December 13, 2011, DART awarded a contract to design and build the Orange Line extension from Belt Line Road to DFW Airport, valued at about $ 150 million, with construction to start in early 2012 and an opening date of August 18, 2014, ahead of schedule. The Orange Line started operation on December 6, 2010, with weekday peak service from
9443-602: The airport. On December 5, 2007, the Dallas Morning News ran a story reporting that DART President Gary Thomas said a previous cost estimate of $ 988 million was too low. The new cost estimate for the 14-mile project was $ 1.8 – $ 1.9 billion, he said. The $ 900 million overrun in costs caused considerable outrage among political leaders in Irving, Texas , the city the line runs through on its way to Dallas/Fort Worth International Airport . The Irving leaders conducted an inquiry into
9576-518: The attractions which drew Julius Caesar to Britain. They are, for the most part, freshwater pearls from mussels. Pearling was banned in the U.K. in 1998 due to the endangered status of river mussels. Discovery and publicity about the sale for a substantial sum of the Abernethy pearl in the River Tay had resulted in heavy exploitation of mussel colonies during the 1970s and 80s by weekend warriors. When it
9709-459: The bailer shell Melo , the giant clam Tridacna , various scallop species, Pen shells Pinna , and the Haliotis iris species of abalone. Pearls of abalone are cultured pearls , or blister pearls, unique to New Zealand waters, and are commonly referred to as 'blue pearls'. They are admired for their luster and naturally bright vibrant colors that are often compared to opal . Another example
9842-435: The build-up of a natural pearl consists of a brown central zone formed by columnar calcium carbonate (usually calcite, sometimes columnar aragonite) and a yellowish to white outer zone consisting of nacre (tabular aragonite). In a pearl cross-section such as the diagram, these two different materials can be seen. The presence of columnar calcium carbonate rich in organic material indicates juvenile mantle tissue that formed during
9975-862: The case of the Disney amusement parks , even a land train . (The usual British term for an aerial tramway is cable car , which in the US usually refers to a ground-level car pulled along by subterranean cables .) The word trolley is often used as a synonym for streetcar in the United States but is usually taken to mean a cart, particularly a shopping cart, in the UK and elsewhere. Many North American transportation planners reserve streetcar for traditional vehicles that operate exclusively in mixed traffic on city streets, while they use light rail to refer to more modern vehicles operating mostly in exclusive rights of way, since they may operate both side-by-side targeted at different passenger groups. The difference between British English and American English terminology arose in
10108-487: The case. Typical stimuli include organic material, parasites, or even damage that displaces mantle tissue to another part of the mollusk's body. These small particles or organisms gain entry when the shell valves are open for feeding or respiration. In cultured pearls, the irritant is typically an introduced piece of the mantle epithelium, with or without a spherical bead (beaded or beadless cultured pearls). Natural pearls are nearly 100% calcium carbonate and conchiolin . It
10241-421: The closure of Glasgow Corporation Tramways (one of the largest in Europe) in 1962. Although some traditional trolley or tram systems continued to exist in San Francisco and elsewhere, the term "light rail" has come to mean a different type of rail system as modern light rail technology has primarily post-WWII West German origins. An attempt by Boeing Vertol to introduce a new American light rail vehicle in
10374-428: The conjunctive tissue of the mantle, these cells may survive and form a small pocket in which they continue to secrete calcium carbonate, their natural product. The pocket is called a pearl sac, and grows with time by cell division. The juvenile mantle tissue cells, according to their stage of growth, secrete columnar calcium carbonate from pearl sac's inner surface. In time, the pearl sac's external mantle cells proceed to
10507-421: The construction area where the rail line and highway intersect. DART estimated that the delay could push the opening of the Las Colinas extension from December 2011 to August 2012; however, DART also advised that it was determined to keep the original schedule and minimize any delays. In June 2010, DART placed new Orange Line construction on indefinite hold due to declining revenue. However, on September 15, 2010,
10640-458: The controversy damaged the images of both natural and cultured pearls. By the 1950s, when a significant number of women in developed countries could afford their own cultured pearl necklace, natural pearls were reduced to a small, exclusive niche in the pearl industry. Previously, natural pearls were found in many parts of the world. Present day natural pearling is confined mostly to the Persian Gulf , in seas off Bahrain . Australia also has one of
10773-425: The cost overruns. Texas State Representative Linda Harper Brown sent an official letter to Mr. Thomas also inquiring about the project's cost overruns. In February 2010, DART officials warned that the first two phases of the Orange Line might be delayed due to TXDOT problems along State Highway 114, which the Orange Line route follows. Utility relocation and road construction was expected to delay access to portions of
10906-503: The culturing process for them dictates a smaller volume output and they can never be mass-produced because, in common with most sea pearls, the oyster can only be nucleated with one pearl at a time, while freshwater mussels are capable of multiple pearl implants. Before the days of cultured pearls, black pearls were rare and highly valued for the simple reason that white pearl oysters rarely produced naturally black pearls, and black pearl oysters rarely produced any natural pearls at all. Since
11039-415: The day. This combination of factors limits roads carrying only automobile commuters to a maximum observed capacity of about 3,000 passengers per hour per lane. The problem can be mitigated by introducing high-occupancy vehicle ( HOV ) lanes and ride-sharing programs, but in most cases, policymakers have chosen to add more lanes to the roads, despite a small risk that in unfavorable situations an extension of
11172-549: The development of pearl culture technology, the black pearl oysters Pinctada margaritifera found in Tahiti and many other Pacific islands including the Cook Islands and Fiji are being extensively used for producing cultured pearls. The rarity of the black cultured pearl is now a "comparative" issue. The black cultured pearl is rare when compared to Chinese freshwater cultured pearls, and Japanese and Chinese akoya cultured pearls, and
11305-750: The direct translation, which is city rail (the Norwegian term, by bane , means the same). However, UMTA finally adopted the term light rail instead. Light in this context is used in the sense of "intended for light loads and fast movement", rather than referring to physical weight. The infrastructure investment is also usually lighter than would be found for a heavy rail system. The American Public Transportation Association (APTA), in its Glossary of Transit Terminology, defines light rail as: ...a mode of transit service (also called streetcar, tramway, or trolley) operating passenger rail cars singly (or in short, usually two-car or three-car, trains) on fixed rails in
11438-490: The early stage of pearl development. Displaced living cells with a well-defined task may continue to perform their function in their new location, often resulting in a cyst . Such displacement may occur via an injury. The fragile rim of the shell is exposed and is prone to damage and injury. Crabs, other predators and parasites such as worm larvae may produce traumatic attacks and cause injuries in which some external mantle tissue cells are disconnected from their layer. Embedded in
11571-401: The form of the mineral aragonite or a mixture of aragonite and calcite (polymorphs with the same chemical formula, but different crystal structures) held together by an organic horn-like compound called conchiolin . The combination of aragonite and conchiolin is called nacre , which makes up mother-of-pearl. The commonly held belief that a grain of sand acts as the irritant is in fact rarely
11704-435: The formation of tabular aragonite. When the transition to nacre secretion occurs, the brown pebble becomes covered with a nacreous coating. During this process, the pearl sac seems to travel into the shell; however, the sac actually stays in its original relative position the mantle tissue while the shell itself grows. After a couple of years, a pearl forms and the shell may be found by a lucky pearl fisher. Cultured pearls are
11837-579: The great majority of these "pearls" are not valued as gemstones . Nacreous pearls, the best-known and most commercially significant, are primarily produced by two groups of molluskan bivalves or clams . A nacreous pearl is made from layers of nacre , by the same living process as is used in the secretion of the mother of pearl which lines the shell. Natural (or wild) pearls, formed without human intervention, are very rare. Many hundreds of pearl oysters or mussels must be gathered and opened, and thus killed, to find even one wild pearl; for many centuries, this
11970-516: The horse conch Triplofusus papillosus . The second largest pearl known was found in the Philippines in 1934 and is known as the Pearl of Lao Tzu . It is a naturally occurring, non-nacreous, calcareous concretion (pearl) from a giant clam . Because it did not grow in a pearl oyster it is not pearly; instead the surface is glossy like porcelain. Other pearls from giant clams are known to exist, but this
12103-454: The host mussel. South Sea and Tahitian pearl oysters, also known as Pinctada maxima and Pinctada margaritifera , which survive the subsequent surgery to remove the finished pearl, are often implanted with a new, larger beads as part of the same procedure and then returned to the water for another 2–3 years of growth. Despite the common misperception, Mikimoto did not discover the process of pearl culture. The accepted process of pearl culture
12236-441: The interim. During weekday peak periods, the eastern segment of the line is extended further north to Richardson and Plano . For publicity purposes, DART light rail is divided into eight corridors, of which the Orange Line serves four. On average, an end-to-end trip on the line will take 76 minutes (if the eastern terminus is LBJ/Central) or 92 minutes (if the eastern terminus is Parker Road). The Irving/DFW Corridor, which has
12369-466: The interior of the shell that produces them. However, almost all species of shelled mollusks are capable of producing pearls (technically "calcareous concretions") of lesser shine or less spherical shape. Although these may also be legitimately referred to as "pearls" by gemological labs and also under U.S. Federal Trade Commission rules, and are formed in the same way, most of them have no value except as curiosities. The English word pearl comes from
12502-438: The intersection of Loop 12 and SH 114 near the former site of Texas Stadium . The city of Irving has established a redevelopment plan for the site which includes the station. South Las Colinas station would be located on Teleport Boulevard near SH 114 and a former BNSF rail corridor. It would serve as an intermodal transit center between DART light rail, a proposed Las Colinas APT System extension, and
12635-435: The largest and rarest of the cultured pearls – making them the most valuable. Prized for their exquisitely beautiful 'orient' or lustre, South Sea pearls are now farmed in various parts of the world where the Pinctada maxima oysters can be found, with the finest South Sea pearls being produced by Paspaley along the remote coastline of North-Western Australia. White and silver colored South Sea pearls tend to come from
12768-453: The late 19th century when Americans adopted the term "street railway", rather than "tramway", with the vehicles being called "streetcars" rather than "trams". Some have suggested that the Americans' preference for the term "street railway" at that time was influenced by German emigrants to the United States (who were more numerous than British immigrants in the industrialized Northeast), as it is
12901-524: The latter is described as light rail. In those places, trams running on mixed rights-of-way are not regarded as a light rail but considered distinctly as streetcars or trams. However, the requirement for saying that a rail line is "separated" can be quite low—sometimes just with concrete "buttons" to discourage automobile drivers from getting onto the tracks. Some systems such as Seattle's Link had on-road mixed sections but were closed to regular road traffic, with light rail vehicles and buses both operating along
13034-455: The light rail concept was the "Shaker Heights Rapid Transit" which started in the 1920s, was renovated in 1980-81 and is now part of RTA Rapid Transit . Many original tram and streetcar systems in the United Kingdom , United States , and elsewhere were decommissioned starting in the 1950s as subsidies for the car increased. Britain abandoned its tram systems, except for Blackpool , with
13167-409: The majority of those currently sold. Imitation pearls are also widely sold in inexpensive jewelry. Pearls have been harvested and cultivated primarily for use in jewelry , but in the past were also used to adorn clothing. They have also been crushed and used in cosmetics, medicines and paint formulations. Whether wild or cultured, gem-quality pearls are almost always nacreous and iridescent , like
13300-575: The non-beaded freshwater cultured pearls, like the Biwa or Chinese pearls. As they grow in the mantle, where on each wing up to 25 grafts can be implanted, these pearls are much more frequent and saturate the market completely. An impressive improvement in quality has taken place over ten years when the former rice-grain-shaped pebbles are compared with the near round pearls of today. Later, large near perfect round bead nucleated pearls up to 15mm in diameter have been produced with metallic luster. The nucleus bead in
13433-523: The northern and western segments of the modern-day Green Line and Orange Line, respectively. In 2006, the two lines (with their current colors) were incorporated into DART's 2030 Transit System Plan, with revenue service to D/FW Airport expected in 2013. On March 12, 2007, the City of Dallas officials and DART made an agreement to make Love Field Station a surface-level facility, concluding a long debate over whether or not to make it an underground station closer to
13566-498: The office of alcalde of Panama. Margarita pearls are extremely difficult to find today and are known for their unique yellowish color. Before the beginning of the 20th century, pearl hunting was the most common way of harvesting pearls. Divers manually pulled oysters from ocean floors and river bottoms and checked them individually for pearls. Not all mussels and oysters produce pearls. In a haul of three tons, only three or four oysters will produce perfect pearls. Pearls were one of
13699-465: The old and new systems. Since the 1980s, Portland, Oregon , has built all three types of system: a high-capacity light rail system in dedicated lanes and rights-of-way, a low-capacity streetcar system integrated with street traffic, and an aerial tram system . The opposite phrase heavy rail , used for higher-capacity, higher-speed systems, also avoids some incompatibilities in terminology between British and American English, for instance in comparing
13832-460: The peak direction during rush hour. Pearl A pearl is a hard, glistening object produced within the soft tissue (specifically the mantle ) of a living shelled mollusk or another animal, such as fossil conulariids . Just like the shell of a mollusk, a pearl is composed of calcium carbonate (mainly aragonite or a mixture of aragonite and calcite ) in minute crystalline form, which has deposited in concentric layers. The ideal pearl
13965-432: The pearl industry is making ongoing attempts to improve culturing technique so that keshi pearls do not occur. All-nacre pearls may one day be limited to natural found pearls. Today many "keshi" pearls are actually intentional, with post-harvest shells returned to the water to regenerate a pearl in the existing pearl sac. Tahitian pearls , frequently referred to as black pearls, are highly valued because of their rarity;
14098-403: The piece of mantle should slip off the bead, a keshi pearl forms of baroque shape about the mantle piece. Therefore, while a keshi pearl could be considered superior to cultured pearls with a mother of pearl bead center, in the cultured pearl industry the oyster's resources used to create a mistaken all-nacre baroque pearl is a drain on the production of the intended round cultured pearl. Therefore,
14231-602: The port of Oruwella in the Gulf of Mannar in Sri Lanka . It also records that eight varieties of pearls accompanied Prince Vijaya 's embassy to the Pandyan king as well as king Devanampiya Tissa 's embassy to Emperor Ashoka . Pliny the Elder (23–79 AD) praised the pearl fishery of the Gulf as most productive in the world. For thousands of years, seawater pearls were retrieved by divers in
14364-540: The required clearance height can be reduced significantly compared to conventional light rail vehicles. Reference speed from major light rail systems, including station stop time, is shown below. However, low top speed is not always a differentiating characteristic between light rail and other systems. For example, the Siemens S70 LRVs used in the Houston METRORail and other North American LRT systems have
14497-404: The response of the shell to a tissue implant. A tiny piece of mantle tissue (called a graft ) from a donor shell is transplanted into a recipient shell, causing a pearl sac to form into which the tissue precipitates calcium carbonate. There are a number of methods for producing cultured pearls: using freshwater or seawater shells, transplanting the graft into the mantle or into the gonad, and adding
14630-486: The right set of circumstances, almost any shelled mollusk can produce some kind of pearl. However, most of these molluskan pearls have no luster or iridescence . The great majority of mollusk species produce pearls which are not attractive, and are sometimes not even very durable. Such pearls usually have no value at all, except perhaps to a scientist or collector, or as a curiosity. These objects used to be referred to as "calcareous concretions" by some gemologists, even though
14763-432: The right-of-way that is often separated from other traffic for part or much of the way. Light rail vehicles are typically driven electrically with power being drawn from an overhead electric line via a trolley [pole] or a pantograph ; driven by an operator onboard the vehicle; and may have either high platform loading or low-level boarding using steps." However, some diesel-powered transit is designated light rail, such as
14896-415: The road network might lead to increased travel times ( Downs–Thomson paradox , Braess's paradox ). By contrast, light rail vehicles can travel in multi-car trains carrying a theoretical ridership up to 20,000 passengers per hour in much narrower rights-of-way , not much more than two car lanes wide for a double track system. They can often be run through existing city streets and parks , or placed in
15029-401: The roads. Typically roadways have 1,900 passenger cars per lane per hour (pcplph). If only cars are allowed, the capacity will be less and will not increase when the traffic volume increases. When there is a bus driving on this route, the capacity of the lane will be higher and will increase when the traffic level increases. And because the capacity of a light rail system is higher than that of
15162-613: The same as the German term for the mode, Straßenbahn (meaning "street railway"). A further difference arose because, while Britain abandoned all of its trams after World War II except in Blackpool , eight major North American cities ( Toronto , Boston , Philadelphia , San Francisco , Pittsburgh , Newark , Cleveland , and New Orleans ) continued to operate large streetcar systems. When these cities upgraded to new technology, they called it light rail to differentiate it from their existing streetcars since some continued to operate both
15295-433: The shape of the implanted shell bead nucleus. After a bead is inserted into the oyster, it secretes a few layers of nacre around the bead; the resulting cultured pearl can then be harvested in as few as twelve to eighteen months. When a cultured pearl with a bead nucleus is X-rayed, it reveals a different structure to that of a natural pearl. A beaded cultured pearl shows a solid center with no concentric growth rings, whereas
15428-408: The standard gauge is that standard railway maintenance equipment can be used on it, rather than custom-built machinery. Using standard gauges also allows light rail vehicles to be conveniently moved around using the same tracks as freight railways. Additionally, wider gauges (e.g. standard gauge) provide more floor clearance on low-floor trams that have constricted pedestrian areas at the wheels, which
15561-541: The surface. When Spanish conquistadors arrived in the Western Hemisphere, they discovered that around the islands of Cubagua and Margarita , some 200 km north of the Venezuelan coast, was an extensive pearl bed (a bed of pearl oysters). One discovered and named pearl, La Peregrina pearl , was offered to Philip II of Spain who intended to give it as a gift for his daughter on the occasion of her marriage, but
15694-551: The system was a success with the public, gaining up to 190,000 passengers per day. Automatic train operation is employed on light rail networks, tracking the position and speed of a train and hence adjusting its movement for safety and efficiency. One line of light rail (requires 7.6 m, 25' right of way) has a theoretical capacity of up to 8 times more than one 3.7 m (12 foot) lane on a freeway, excluding busses, during peak times. Roads have ultimate capacity limits that can be determined by traffic engineering , and usually experience
15827-499: The trams, making it safe on city streets. Several systems in Europe and a few recently opened systems in North America use diesel -powered trains. When electric streetcars were introduced in the late 19th century, conduit current collection was one of the first ways of supplying power, but it proved to be much more expensive, complicated, and trouble-prone than overhead wires . When electric street railways became ubiquitous, conduit power
15960-810: The use of this X-ray technique. Natural and cultured pearls can be distinguished from imitation pearls using a microscope . Another method of testing for imitations is to rub two pearls against each other. Imitation pearls are completely smooth, but natural and cultured pearls are composed of nacre platelets, making both feel slightly gritty. Fine quality natural pearls are very rare jewels. Their values are determined similarly to those of other precious gems, according to size, shape, color, quality of surface, orient and luster. Single natural pearls are often sold as collectors' items, or set as centerpieces in unique jewelry. Very few matched strands of natural pearls exist, and those that do often sell for hundreds of thousands of dollars. (In 1917, jeweler Pierre Cartier purchased
16093-455: The vast majority of light rail systems. This avoids the danger potentially presented by an electrified third rail . The Docklands Light Railway uses an inverted third rail for its electrical power, which allows the electrified rail to be covered and the power drawn from the underside. Trams in Bordeaux , France, use a special third-rail configuration where the power is only switched on beneath
16226-434: The widest range of latitude of any rail system in the design, engineering, and operating practices. The challenge in designing light rail systems is to realize the potential of LRT to provide fast, comfortable service while avoiding the tendency to overdesign that results in excessive capital costs beyond what is necessary to meet the public's needs. The BART railcar in the following chart is not generally considered to be
16359-468: The world's last remaining fleets of pearl diving ships. Australian pearl divers dive for south sea pearl oysters to be used in the cultured south sea pearl industry. The catch of pearl oysters is similar to the numbers of oysters taken during the natural pearl days. Hence significant numbers of natural pearls are still found in the Australian Indian Ocean waters from wild oysters. X-ray examination
16492-527: Was coined in 1972 by the U.S. Urban Mass Transportation Administration (UMTA; the precursor to the Federal Transit Administration ) to describe new streetcar transformations that were taking place in Europe and the United States. In Germany, the term Stadtbahn (to be distinguished from S-Bahn , which stands for Stadtschnellbahn ) was used to describe the concept, and many in UMTA wanted to adopt
16625-543: Was developed by the British Biologist William Saville-Kent in Australia and brought to Japan by Tokichi Nishikawa and Tatsuhei Mise. Nishikawa was granted the patent in 1916, and married the daughter of Mikimoto. Mikimoto was able to use Nishikawa's technology. After the patent was granted in 1916, the technology was immediately commercially applied to akoya pearl oysters in Japan in 1916. Mise's brother
16758-662: Was introduced in North America in 1972 to describe this new concept of rail transportation. Prior to that time the abbreviation "LRT" was used for " Light Rapid Transit " and " Light Rail Rapid Transit ". The first of the new light rail systems in North America began operation in 1978 when the Canadian city of Edmonton, Alberta , adopted the German Siemens-Duewag U2 system, followed three years later by Calgary, Alberta , and San Diego, California . The concept proved popular, with there now being numerous light rail systems in
16891-408: Was originally set for completion in 2028 but is currently on hiatus. The original Northwest Corridor plan included two stations which were deferred pending future development of their surrounding sites. To date, neither station has been constructed. While not listed as such in the original plan, Hidden Ridge station was also deferred until its opening in 2021. Loop 12 station would be located at
17024-661: Was permitted it was carried on mainly by Scottish Travellers who found pearls varied from river to river with the River Oykel in the Highlands being noted for the finest rose-pink pearls. There are two firms in Scotland that are licensed to sell pre-1998 freshwater pearls. Today, the cultured pearls on the market can be divided into two categories. The first category covers the beaded cultured pearls, including akoya, South Sea and Tahiti. These pearls are gonad grown, and usually one pearl
17157-454: Was planned with the rest of the Orange Line but deferred until further development justified its construction, opened to revenue service on April 12, 2021. When the extension to the airport was created, the western terminus of the proposed Cotton Belt Corridor (now the Silver Line ) was DFW Airport North . To enable transfers to the airport, a secondary extension would add DFW Airport North to
17290-610: Was the Gross-Lichterfelde tramway in Lichterfelde near Berlin in Germany, which opened in 1881. It was built by Werner von Siemens who contacted Pirotsky. It initially drew current from the rails, with overhead wire being installed in 1883. The first interurban to emerge in the United States was the Newark and Granville Street Railway in Ohio, which opened in 1889. An early example of
17423-527: Was the first to produce a commercial crop of pearls in the akoya oyster. Mitsubishi's Baron Iwasaki immediately applied the technology to the south sea pearl oyster in 1917 in the Philippines, and later in Buton, and Palau. Mitsubishi was the first to produce a cultured south sea pearl – although it was not until 1928 that the first small commercial crop of pearls was successfully produced. The original Japanese cultured pearls, known as akoya pearls, are produced by
17556-418: Was the only way pearls were obtained, and why pearls fetched such extraordinary prices in the past. Cultured pearls are formed in pearl farms, using human intervention as well as natural processes. One family of nacreous pearl bivalves – the pearl oyster – lives in the sea, while the other – a very different group of bivalves – lives in freshwater; these are the river mussels such as
17689-517: Was used in those cities that did not permit overhead wires. In Europe, it was used in London, Paris, Berlin, Marseille, Budapest, and Prague. In the United States, it was used in parts of New York City and Washington, D.C. Third rail technology was investigated for use on the Gold Coast of Australia for the G:link light rail, though power from overhead lines was ultimately utilized for that system. In
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