How Do You Select The Best Driveway or Driveway Pavers?
Driveway to a farm Driveway apron and sloped curb to a public street, all under construction
A driveway (also called drive in UK English) Driveway Pavers in Sandton is a type of private road for local access to one or a small group of structures, and is owned and maintained by an individual or group.
Driveways rarely have traffic lights, but some that bear heavy traffic, especially those leading to commercial businesses and parks, do.
Driveways may be decorative in ways that public roads cannot, because of their lighter traffic and the willingness of owners to invest in their construction. Driveways are not resurfaced, snow blown or otherwise maintained by governments. They are generally designed to conform to the architecture of connected houses or other buildings.
Some of the materials that can be used for driveways include concrete, decorative brick, cobblestone, block paving, asphalt, gravel, decomposed granite, and surrounded with grass or other ground-cover plants.
Driveways are commonly used as paths to private garages, carports, or houses. On large estates, a driveway may be the road that leads to the house from the public road, possibly with a gate in between. Some driveways divide to serve different homeowners. A driveway may also refer to a small apron of pavement in front of a garage with a curb cut in the sidewalk, sometimes too short to accommodate a car.
Often, either by choice or to conform with local regulations, cars are parked in driveways in order to leave streets clear for traffic. Moreover, some jurisdictions prohibit parking or leaving standing any motor vehicle upon any residential lawn area (defined as the property from the front of a residential house, condominium, or cooperative to the street line other than a driveway, walkway, concrete or blacktopped surface parking space). Other examples include the city of Berkeley, California that forbids “any person to park or leave standing, or cause to be parked or left standing any vehicle upon any public street in the City for seventy-two or more consecutive hours.” Other areas may prohibit leaving vehicles on residential streets during certain times (for instance, to accommodate regular street cleaning), necessitating the use of driveways.
Residential driveways are also used for such things as garage sales, automobile washing and repair, and recreation, notably (in North America) for basketball practice.
Another form of driveway is a ‘Run-Up’, or short piece of land used usually at the front of the property to park a vehicle on.
Interesting Facts About Driveway Pavers in Rivonia:
About Driveway Pavers in Rivonia:An alley in Fira, Santorini, Greece Sana'a, Yemen Howey Place, Melbourne, Australia Hagay Street, Old City, Jerusalem Rua Sobre-o-Douro, Porto, Portugal Peg Washington's Lane, Graiguenamanagh, County Kilkenny, Ireland
An alley or alleyway is a narrow lane, path, or passageway, often reserved for pedestrians, which usually runs between, behind, or within buildings in the older parts of towns and cities. It is also a rear access or service road (back lane), or a path or walk in a park or garden.
A covered alley or passageway, often with shops, may be called an arcade. The origin of the word alley is late Middle English, from Old French: alee "walking or passage", from aler "go", from Latin: ambulare "to walk".
The word alley is used in two main ways:Grand Bazaar, Istanbul
In older cities and towns in Europe, alleys are often what is left of a medieval street network, or a right of way or ancient footpath. Similar paths also exist in some older North American towns and cities. In some older urban development in North America lanes at the rear of houses, to allow for deliveries and garbage collection, are called alleys. Alleys and ginnels were also the product of the 1875 Public Health Act in the United Kingdom, where usually alleys run along the back of streets of terraced houses, with ginnels connecting them to the street every fifth house. Alleys may be paved, or unpaved, and a blind alley is a cul-de-sac. Modern urban developments may also provide a service road to allow for waste collection, or rear access for fire engines and parking.
Because of geography, steps (stairs) are the predominant form of alley in hilly cities and towns. This includes Pittsburgh (see Steps of Pittsburgh), Cincinnati (see Steps of Cincinnati), Minneapolis, Seattle, and San Francisco in the United States, as well as Hong Kong, Genoa and Rome.
Some alleys are roofed because they are within buildings, such as the traboules of Lyon, or when they are a pedestrian passage through railway embankments in Britain. The latter follow the line of rights-of way that existed before the railway was built.
Arcades are another kind of covered passageway and the simplest kind are no more than alleys to which a glass roof was added later, like, for example, Howey Place, Melbourne, Australia (see also Block Place, Melbourne). However, most arcades differ from alleys in that they are architectural structures built with a commercial purpose and are a form of shopping mall. All the same alleys have for long been associated with various types of businesses, especially pubs and coffee houses. Bazaars and Souqs are an early form of arcade found in Asia and North Africa.
Some attractive historic alleys are found in older American and Canadian cities, like New York City, Philadelphia, Charleston, South Carolina, Boston, Annapolis, New Castle, Delaware, Quebec City, St John's, Newfoundland, and Victoria, British Columbia.View into Fan Tan Alley, Victoria, British Columbia, Canada
Québec City was originally built on the riverside bluff Cap Diamant in the 17th century, and throughout Quebec City there are strategically placed public stairways that link the bluff to the lower parts of the city. The Upper City is the site of Old Québec’s most significant historical sites, including 17th- and 18th-century chapels, the Citadel and the city ramparts.
Fan Tan Alley is an alley in Victoria, British Columbia's Chinatown. It was originally a gambling district with restaurants, shops, and opium dens. Today it is a tourist destination with many small shops including a barber shop, art gallery, Chinese cafe and apartments. It may well be the narrowest street in Canada. At its narrowest point it is only 0.9 metres (35 in) wide. Waddington Alley is another interesting alley in Victoria and the only street in that city still paved with wood blocks, an early pavement common in the downtown core. Other heritage features are buildings more than a century old lining the alley and a rare metal carriage curb that edges the sidewalk on the southern end.Looking south down Shubert Alley in Manhattan's Theater District
In the United States alleys exist in both older commercial and residential areas, for both service purposes and automobile access. In residential areas, particularly in those that were built before 1950, alleys provide rear access to property where a garage was located, or where waste could be collected by service vehicles. A benefit of this was the location of these activities to the rear, less public side of a dwelling. Such alleys are generally roughly paved, but some may be dirt. Beginning in the late 20th century, they were seldom included in plans for new housing developments.
When Annapolis, Maryland, was established as a city at the beginning of the 18th century, the streets were established in circles. That encouraged the creation of shortcuts, which over time became paved alleys. Some ten of these survive, and the city has recently worked on making them more attractive.
Several residential neighborhoods in Austin, Texas, have comprehensive alley systems. These include Hyde Park, Rosedale, and areas northwest of the Austin State Hospital.
In the Beacon Hill district of Boston, Massachusetts, Acorn Street, a narrow cobbled lane with row houses, is one of Boston's more attractive and historic alleys. Another early settled American city, New Castle, Delaware has a number of interesting alleys, some of which are footpaths and others narrow, sometimes cobbled, lanes open to traffic. Many of the alleys in the Back Bay and South End area are numbered (e.g. "Public Alley 438").
In the French Quarter of Charleston’s historic district, Philadelphia Alley (c. 1766), originally named "Cow Alley", is one of several picturesque alleys. In 1810 William Johnson gave it the name of "Philadelphia Alley", although locals call the "elegantly landscaped thoroughfare" "Dueler’s Alley". Starting on East Bay Street, Stolls Alley is just seventeen bricks wide at its start, and named for Justinus Stoll, an 18th-century blacksmith. For three hundred years, another of Charleston's narrow lanes, Lodge Alley, served a commercial purpose. Originally French Hugenot merchants built homes on it, along with warehouses to store supplies their ships. Just ten-foot-wide this alley was a useful means of access to Charleston’s waterways. Today it leads to East Bay Street's many restaurants.Main article: Steps of Cincinnati
Cincinnati is a city of hills. Before the advent of the automobile a system of stairway alleys provided pedestrians important and convenient access to and from their hill top homes. At the height of their use in the 19th century, over 30 miles (48 km) of hill side steps once connected the neighborhoods of Cincinnati to each other. The first steps were installed by residents of Mount Auburn in the 1830s in order to gain easier access to Findlay Market in Over-the-Rhine. In recent years many steps have fallen into disrepair but there is a movement now to rehabilitate them.Broadway Alley is a rare alley in Manhattan; it is not located near Broadway, East Broadway or West Broadway
New York City's Manhattan is unusual in that it has very few alleys, since the Commissioner's Plan of 1811 did not include rear service alleys when it created Manhattan's grid. The exclusion of alleys has been criticized as a flaw in the plan, since services such as garbage pickup cannot be provided out of sight of the public, although other commentators feel that the lack of alleys is a benefit to the quality of life of the city.
Two notable alleys in the Greenwich Village neighborhood in Manhattan are MacDougal Alley and Washington Mews. The latter is a blind alley or cul-de-sac. Greenwich Village also has a number of private alleys that lead to back houses, which can only be accessed by residents, including Grove Court, Patchin Place and Milligan Place, blind alleys. Patchin Place is notable for the writers who lived there.
Shubert Alley is a 300-foot (91 m) long pedestrian alley at the heart of the Broadway theater district of New York City. The alley was originally created as a fire exit between the Shubert Theatre on West 45th Street and the Booth Theatre on West 44th Street, and the Astor Hotel to their east. Actors once gathered in the alley, hoping to attract the attention of the Shubert Brothers and get employment in their theatrical productions. When the hotel was torn down, and replaced with One Astor Plaza (1515 Broadway), the apparent width of the alley increased, as the new building did not go all the way to the westernmost edge of the building lot. However, official, Shubert Alley consists only of the space between the two theatres and the lot line.
In the Brooklyn Heights neighborhood of Brooklyn, Grace Court Alley is another converted mews, as is Dennett Place in the Carroll Gardens neighborhood. The former is a cul-de-sac.Pedestrians walking along Elfreth's Alley, Philadelphia
The Old City and Society Hill neighborhoods of Philadelphia, the oldest parts of the city, include a number of alleys, notably Elfreth's Alley, which is called "Our nation's oldest residential street", dating from 1702. As of 2012[update], there were 32 houses on the street, which were built between 1728 and 1836.
There are numerous cobblestoned residential passages in Philadelphia, many no wider than a truck, and typically flanked with brick houses. A typical house on these alleys or lanes is called a Philadelphia "Trinity", named because it has three rooms, one to each floor, alluding to the Christian Trinity. These alleys include Willings Alley, between S. 3rd and S. 4th Streets and Walnut and Spruce Streets. Other streets in Philadelphia which fit the general description of an alley, but are not named "alley", include Cuthbert Street, Filbert Street, Phillips Street, South American Street, Sansom Walk, St. James Place, and numerous others.
Steps, Pittsburgh's equivalent for an alley, have defined it for many visitors. Writing in 1937, war correspondent Ernie Pyle wrote of the steps of Pittsburgh:
And then the steps. Oh Lord, the steps! I was told they actually had a Department of Steps. That isn’t exactly true, although they do have an Inspector of Steps. But there are nearly 15 miles (24 km) of city-owned steps, going up mountainsides.
The City of Pittsburgh maintains 712 sets of city-owned steps, some of which are shown as streets on maps.
In hilly San Francisco, California alleys often take the form of steps and it has several hundred public stairways. Among the most famous is the stairway known as the Filbert steps, a continuation of Filbert Street. The Filbert Street Steps descend the east slope of Telegraph Hill along the line where Filbert Street would be if the hill was not so steep. The stairway is bordered by greenery, that consists both backyards, and a border garden tended to and paid for by the residents of the "street", and runs down to an eastern stub of Filbert Street and the walkway through the plaza to The Embarcadero. Many houses in this residential neighborhood are accessible only from the steps.
Also in San Francisco, Belden Place is a narrow pedestrian alley, bordered by restaurants, in the Financial District, referred to as San Francisco's French Quarter for its historic ties to early French immigrants, and its popular contemporary French restaurants and institutions. The area was home to San Francisco's first French settlers. Approximately 3,000, sponsored by the French government, arrived near the end of the Gold Rush in 1851.Alley in Sausalito, California
Seattle is a city of hills, bluffs, and canyons and many stairs. There are over 600 publicly accessible Seattle stairways within the city limits.Ruelle verte (Green alley) Montréal, Québec, Canada.
Numerous cities in the United States and Canada, such as Chicago, Seattle, Los Angeles, Phoenix, Washington, D.C., and Montréal, have started reclaiming their alleys from garbage and crime by greening the service lanes, or back ways, that run behind some houses. Chicago, Illinois has about 1,900 miles (3,100 km) of alleyways. In 2007, the Chicago Department of Transportation started converting conventional alleys which were paved with asphalt into so called Green Alleys. This program, called the Green Alley Program, is supposed to enable easier water runoff, as the alleyways in Chicago are not connected directly to the sewer system. With this program, the water will be able to seep through semi-permeable concrete or asphalt in which a colony of fungi and bacteria will establish itself. The bacteria will help breakup oils before the water is absorbed into the ground. The lighter color of the pavement will also reflect more light, making the area next to the alley cooler. The greening of such alleys or laneways can also involve the planting of native plants to further absorb rain water and moderate temperature.
New life has also come to other alleys within downtown commercial districts of various cities throughout the world with the opening of businesses, such as coffee houses, shops, restaurants and bars.
Another way that alleys and laneways are being revitalized is through laneway housing. A laneway house is a form of housing that has been proposed on the west coast of Canada, especially in the Metro Vancouver area. These homes are typically built into pre-existing lots, usually in the backyard and opening onto the back lane. This form of housing already exists in Vancouver, and revised regulations now encourage new developments as part of a plan to increase urban density in pre-existing neighbourhoods while retaining a single-family feel to the area. Vancouver's average laneway house is one and a half stories, with one or two bedrooms. Typical regulations require that the laneway home is built on the back half of a traditional lot in the space normally reserved for a garage.
Toronto also has a tradition of laneway housing and changed regulations to encourage new development. However this was discontinued in 2006 after staff reviewed the impact on services and safety.
London has numerous historical alleys, especially, but not exclusively, in its centre; this includes The City, Covent Garden, Holborn, Clerkenwell, Westminster and Bloomsbury amongst others.
An alley in London can also be called a passage, court, place, lane, and less commonly path, arcade, walk, steps, yard, terrace, and close. While both a court and close are usually defined as blind alleys, or cul-de-sacs, several in London are throughways, for example Cavendish Court, a narrow passage leading from Houndsditch into Devonshire Square, and Angel Court, which links King Street and Pall Mall. Bartholomew Close is a narrow winding lane which can be called an alley by virtue of its narrowness, and because through-access requires the use of passages and courts between Little Britain, and Long Lane and Aldersgate Street.
In an old neighbourhood of the City of London, Exchange Alley or Change Alley is a narrow alleyway connecting shops and coffeehouses. It served as a convenient shortcut from the Royal Exchange on Cornhill to the Post Office on Lombard Street and remains as one of a number of alleys linking the two streets. The coffeehouses of Exchange Alley, especially Jonathan's and Garraway's, became an early venue for the lively trading of shares and commodities. These activities were the progenitor of the modern London Stock Exchange.Boundary Passage, Shoreditch, London, England
Lombard Street and Change Alley had been the open-air meeting place of London's mercantile community before Thomas Gresham founded the Royal Exchange in 1565. In 1698, John Castaing began publishing the prices of stocks and commodities in Jonathan's Coffeehouse, providing the first evidence of systematic exchange of securities in London.
Change Alley was the site of some noteworthy events in England's financial history, including the South Sea Bubble from 1711 to 1720 and the panic of 1745.
In 1761 a club of 150 brokers and jobbers was formed to trade stocks. The club built its own building in nearby Sweeting's Alley in 1773, dubbed the "New Jonathan's", later renamed the Stock Exchange.
West of the City there are a number of alleys just north of Trafalgar Square, including Brydges Place which is situated right next to the Coliseum Theatre and just 15 inches wide at its narrowest point, only one person can walk down it at a time. It is the narrowest alley in London and runs for 200 yards (180 m), connecting St Martin's Lane with Bedfordbury in Covent Garden.
Close by is another very narrow passage, Lazenby Court, which runs from Rose Street to Floral Street down the side of the Lamb and Flag pub; in order to pass people must turn slightly sideways. The Lamb & Flag in Rose Street has a reputation as the oldest pub in the area, though records are not clear. The first mention of a pub on the site is 1772. The Lazenby Court was the scene of an attack on the famous poet and playwright John Dryden in 1679 by thugs hired by John Wilmot, 2nd Earl of Rochester, with whom he had a long-standing conflict.
In the same neighbourhood Cecil Court has an entirely different character than the two previous alleys, and is a spacious pedestrian street with Victorian shop-frontages that links Charing Cross Road with St. Martin's Lane, and it is sometimes used as a location by film companies.
One of the older thoroughfares in Covent Garden, Cecil Court dates back to the end of the 17th century. A tradesman's route at its inception, it later acquired the nickname Flicker Alley because of the concentration of early film companies in the Court. The first film-related company arrived in Cecil Court in 1897, a year after the first demonstration of moving pictures in the United Kingdom and a decade before London’s first purpose built cinema opened its doors. Since the 1930s it has been known as the new Booksellers' Row as it is home to nearly twenty antiquarian and second-hand independent bookshops.
It was the temporary home of an eight-year-old Wolfgang Amadeus Mozart while he was touring Europe in 1764. For almost four months the Mozart family lodged with barber John Couzin. According to some modern authorities, Mozart composed his first symphony while a resident of Cecil Court.
North of the centre of London, Camden Passage is a pedestrian passage off Upper Street in the London Borough of Islington, famous because of its many antiques shops, and an antique market on Wednesdays and Saturday mornings. It was built, as an alley, along the backs of houses on Upper Street, then Islington High Street, in 1767.An alley (usually called a ginnel) in Moss Side, Manchester Tolbooth Wynd, Edinburgh
In Scotland and Northern Ireland the Scots terms close, wynd, pend and vennel are general in most towns and cities. The term close has an unvoiced "s" as in sad. The Scottish author Ian Rankin's novel Fleshmarket Close was retitled Fleshmarket Alley for the American market. Close is the generic Scots term for alleyways, although they may be individually named closes, entries, courts and wynds. A close was private property, hence gated and closed to the public.
A wynd is typically a narrow lane between houses, an open throughway, usually wide enough for a horse and cart. The word derives from Old Norse venda, implying a turning off a main street, without implying that it is curved. In fact, most wynds are straight. In many places wynds link streets at different heights and thus are mostly thought of as being ways up or down hills.
A pend is a passageway that passes through a building, often from a street through to a courtyard, and typically designed for vehicular rather than exclusively pedestrian access. A pend is distinct from a vennel or a close, as it has rooms directly above it, whereas vennels and closes are not covered over.
A vennel is a passageway between the gables of two buildings which can in effect be a minor street in Scotland and the north east of England, particularly in the old centre of Durham. In Scotland, the term originated in royal burghs created in the twelfth century, the word deriving from the Old French word venelle meaning "alley" or "lane". Unlike a tenement entry to private property, known as a "close", a vennel was a public way leading from a typical high street to the open ground beyond the burgage plots. The Latin form is venella.Traboule, Vieux Lyon, France
The traboules of Lyon are passageways that cut through a house or, in some cases, a whole city block, linking one street with another. They are distinct from most other alleys in that they are mainly enclosed within buildings and may include staircases. While they are found in other French cities including Villefranche-sur-Saône, Mâcon, Chambéry, Saint-Étienne, Louhans, Chalon sur Saône and Vienne (Isère), Lyon has many more; in all there are about 500. The word traboule comes from the Latin trans ambulare, meaning "to cross", and the first of them were possibly built as early as the 4th century. As the Roman Empire disintegrated, the residents of early Lyon—Lugdunum, the capital of Roman Gaul—were forced to move from the Fourvière hill to the banks of the river Saône when their aqueducts began to fail. The traboules grew up alongside their new homes, linking the streets that run parallel to the river Saône and going down to the river itself. For centuries they were used by people to fetch water from the river and then by craftsmen and traders to transport their goods. By the 18th century they were invaluable to what had become the city’s defining industry, textiles, especially silk. Nowadays, traboules are tourist attractions, and many are free and open to the public. Most traboules are on private property, serving as entrances to local apartments.
Venice is largely a traffic free city and there is, in addition to the canals, a maze of around 3000 lanes and alleys called calli (which means narrow). Smaller ones are callètte or callesèlle, while larger ones are calli large. Their width varies from just over 50 centimetres (19.7 in) to 5–6 metres (196.9–236.2 in). The narrowest is Calletta Varisco, which just 53 centimetres (20.9 in); Calle Stretta is 65 centimetres (25.6 in) wide and Calle Ca’ Zusto 68 centimetres (26.8 in). The main ones are also called salizada and wider calli, where trade proliferates, are called riga', while blind calli, used only by residents to reach their homes, are ramo.
Spreuerhofstraße is the world's narrowest street, found in the city of Reutlingen, Baden-Württemberg, Germany. It ranges from 31 centimetres (12.2 in) at its narrowest to 50 centimetres (19.7 in) at its widest. The lane was built in 1727 during the reconstruction efforts after the area was completely destroyed in the massive citywide fire of 1726 and is officially listed in the Land-Registry Office as City Street Number 77.
Lintgasse is an alley (German: Gasse) in the Old town of Cologne, Germany between the two squares of Alter Markt and Fischmarkt. It is a pedestrian zone and though only some 130 metres long, is nevertheless famous for its medieval history. The Lintgasse was first mentioned in the 12th century as in Lintgazzin, which may be derived from basketmakers who wove fish baskets out of Linden tree barks. These craftsmen were called Lindslizer, meaning Linden splitter. During the Middle Ages, the area was also known as platēa subri or platēa suberis, meaning street of Quercus suber, the cork oak tree. Lintgasse 8 to 14 used to be homes of medieval knights as still can be seen by signs like Zum Huynen, Zum Ritter or Zum Gir. During the 19th-century the Lintgasse was called Stink-Linkgaß, a because of its poor air quality.A view of Spreuerhofstraße in Germany, showing the sign indicating that is the world's record narrowest street
Gränd is Swedish for an alley and there are numerous gränder, or alleys in Gamla stan, The Old Town, of Stockholm, Sweden. The town dates back to the 13th century, with medieval alleyways, cobbled streets, and historic buildings. North German architecture has had a strong influence in the Old Town's buildings. Some of Stockholm's alleys are very narrow pedestrian footpaths, while others are very narrow, cobbled streets, or lanes open to slow moving traffic. Mårten Trotzigs gränd ("Alley of Mårten Trotzig") runs from Västerlånggatan and Järntorget up to Prästgatan and Tyska Stallplan, and part of it consists of 36 steps. At its narrowest the alley is a mere 90 cm (35 inches) wide, making it the narrowest street in Stockholm. The alley is named after the merchant and burgher Mårten Trotzig (1559–1617), who, born in Wittenberg, emigrated to Stockholm in 1581, and bought properties in the alley in 1597 and 1599, also opening a shop there. According to sources from the late 16th century, he was dealing in first iron and later copper, by 1595 had sworn his burgher oath, and was later to become one of the richest merchants in Stockholm.Mårten Trotzigs Gränd, 90 cm wide, the narrowest alley in Gamla stan, Stockholm, Sweden
Possibly referred to as Trångsund ("Narrow strait") before Mårten Trotzig gave his name to the alley, it is mentioned in 1544 as Tronge trappe grenden ("Narrow Alley Stairs"). In 1608 it is referred to Trappegrenden ("The Stairs Alley"), but a map dated 1733 calls it Trotz gränd. Closed off in the mid 19th century, not to be reopened until 1945, its present name was officially sanctioned by the city in 1949.
The "List of streets and squares in Gamla stan" provides links to many pages that describe other alleys in the oldest part of Stockholm; e.g. Kolmätargränd (Coal Meter's Alley); Skeppar Karls Gränd (Skipper Karl's Alley); Skeppar Olofs Gränd (Skipper Olof's Alley); and Helga Lekamens Gränd (Alley of the Holy Body).A hutong in Beijing
Hutongs (simplified Chinese: 胡同; traditional Chinese: 衚衕; pinyin: hútòng; Wade–Giles: hu-t'ung) are a type of narrow streets or alleys, commonly associated with northern Chinese cities, most prominently Beijing.
In Beijing, hutongs are alleys formed by lines of siheyuan, traditional courtyard residences. Many neighbourhoods were formed by joining one siheyuan to another to form a hutong, and then joining one hutong to another. The word hutong is also used to refer to such neighbourhoods. During China’s dynastic period, emperors planned the city of Beijing and arranged the residential areas according to the social classes of the Zhou Dynasty (1027 – 256 BC). The term "hutong" appeared first during the Yuan Dynasty, and is a term of Mongolian origin meaning "town".
At the turn of the 20th century, the Qing court was disintegrating as China’s dynastic era came to an end. The traditional arrangement of hutongs was also affected. Many new hutongs, built haphazardly and with no apparent plan, began to appear on the outskirts of the old city, while the old ones lost their former neat appearance.
Following the founding of the People’s Republic of China in 1949, many of the old hutongs of Beijing disappeared, replaced by wide boulevards and high rises. Many residents left the lanes where their families lived for generations for apartment buildings with modern amenities. In Xicheng District, for example, nearly 200 hutongs out of the 820 it held in 1949 have disappeared. However, many of Beijing’s ancient hutongs still stand, and a number of them have been designated protected areas. Many hutongs, some several hundred years old, in the vicinity of the Bell Tower and Drum Tower and Shichahai Lake are preserved amongst recreated contemporary two- and three-storey versions.A longtang in Shangxian Fang, a residential compound in Shanghai, China.
Hutongs represent an important cultural element of the city of Beijing and the hutongs are residential neighborhoods which still form the heart of Old Beijing. While most Beijing hutongs are straight, Jiudaowan (九道弯, literally "Nine Turns") Hutong turns nineteen times. At its narrowest section, Qianshi Hutong near Qianmen (Front Gate) is only 40 centimeters (16 inches) wide.
The Shanghai longtang is loosely equivalent to the hutong of Beijing. A longtang (弄堂 lòngtáng, Shanghainese: longdang) is a laneway in Shanghai and, by extension, a community centred on a laneway or several interconnected laneways. On its own long (traditional Chinese 衖 or 弄, simplified Chinese 弄) is a Chinese term for "alley" or "lane", which is often left untranslated in Chinese addresses, but may also be translated as "lane", and "tang" is a parlor or hallway. It is sometimes called lilong (里弄); the latter name incorporates the -li suffix often used in the name of residential developments in the late 19th and early 20th centuries. As with the term hutong, the Shanghai longdang can either refers to the lanes that the houses face onto, or a group of houses connected by the lane.A Golden Gai alley, Tokyo, Japan.
Shinjuku Golden Gai (新宿ゴールデン街) is a small area of Shinjuku, Tokyo, Japan, famous both as an area of architectural interest and for its nightlife. It is composed of a network of six narrow alleys, connected by even narrower passageways which are just about wide enough for a single person to pass through. Over 200 tiny shanty-style bars, clubs and eateries are squeezed into this area.
Its architectural importance is that it provides a view into the relatively recent past of Tokyo, when large parts of the city resembled present-day Golden Gai, particularly in terms of the extremely narrow lanes and the tiny two-storey buildings. Nowadays, most of the surrounding area has been redeveloped. Typically, the buildings are just a few feet wide and are built so close to the ones next door that they nearly touch. Most are two-storey, having a small bar at street level and either another bar or a tiny flat upstairs, reached by a steep set of stairs. None of the bars are very large; some are so small that they can only fit five or so customers at one time. The buildings are generally ramshackle, and the alleys are dimly lit, giving the area a very scruffy and run-down appearance. However, Golden Gai is not a cheap place to drink, and the clientele that it attracts is generally well off.
Golden Gai is well known as a meeting place for musicians, artists, directors, writers, academics and actors, including many celebrities. Many of the bars only welcome regular customers, who initially should be introduced by an existing patron, although many others welcome non-regulars, some even making efforts to attract overseas tourists by displaying signs and price lists in English.
Golden Gai was known for prostitution before 1958, when prostitution became illegal. Since then it has developed as a drinking area, and at least some of the bars can trace their origins back to the 1960s.
A medina quarter (Arabic: المدينة القديمة al-madīnah al-qadīmah "the old city") is a distinct city section found in many North African cities. The medina is typically walled, contains many narrow and maze-like streets. The word "medina" (Arabic: مدينة madīnah) itself simply means "city" or "town" in modern Arabic.
Because of the very narrow streets, medinas are generally free from car traffic, and in some cases even motorcycle and bicycle traffic. The streets can be less than a metre wide. This makes them unique among highly populated urban centres. The Medina of Fes, Morocco or Fes el Bali, is considered one of the largest car-free urban areas in the world.
Driveway Pavers in RivoniaFor other uses, see Asphalt (disambiguation). Note: The terms bitumen and asphalt are mostly interchangeable, except where asphalt is used as a shorthand for asphalt concrete. Natural bitumen from the Dead Sea Refined asphalt The University of Queensland pitch drop experiment, demonstrating the viscosity of asphalt
Asphalt (/ˈæsˌfɔːlt, -ˌfɑːlt/), also known as bitumen (UK English: /ˈbɪtʃəmən, ˈbɪtjʊmən/, US English: /bɪˈt(j)uːmən, baɪˈt(j)uːmən/) is a sticky, black, and highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term asphaltum was also used. The word is derived from the Ancient Greek ἄσφαλτος ásphaltos.
The primary use (70%) of asphalt is in road construction, where it is used as the glue or binder mixed with aggregate particles to create asphalt concrete. Its other main uses are for bituminous waterproofing products, including production of roofing felt and for sealing flat roofs.
The terms "asphalt" and "bitumen" are often used interchangeably to mean both natural and manufactured forms of the substance. In American English, "asphalt" (or "asphalt cement") is commonly used for a refined residue from the distillation process of selected crude oils. Outside the United States, the product is often called "bitumen", and geologists worldwide often prefer the term for the naturally occurring variety. Common colloquial usage often refers to various forms of asphalt as "tar", as in the name of the La Brea Tar Pits.
Naturally occurring asphalt is sometimes specified by the term "crude bitumen". Its viscosity is similar to that of cold molasses while the material obtained from the fractional distillation of crude oil boiling at 525 °C (977 °F) is sometimes referred to as "refined bitumen". The Canadian province of Alberta has most of the world's reserves of natural asphalt in the Athabasca oil sands, which cover 142,000 square kilometres (55,000 sq mi), an area larger than England.
The word "asphalt" is derived from the late Middle English, in turn from French asphalte, based on Late Latin asphalton, asphaltum, which is the latinisation of the Greek ἄσφαλτος (ásphaltos, ásphalton), a word meaning "asphalt/bitumen/pitch", which perhaps derives from ἀ-, "without" and σφάλλω (sfallō), "make fall". The first use of asphalt by the ancients was in the nature of a cement for securing or joining together various objects, and it thus seems likely that the name itself was expressive of this application. Specifically, Herodotus mentioned that bitumen was brought to Babylon to build its gigantic fortification wall. From the Greek, the word passed into late Latin, and thence into French (asphalte) and English ("asphaltum" and "asphalt"). In French, the term asphalte is used for naturally occurring asphalt-soaked limestone deposits, and for specialised manufactured products with fewer voids or greater bitumen content than the "asphaltic concrete" used to pave roads.
The expression "bitumen" originated in the Sanskrit words jatu, meaning "pitch", and jatu-krit, meaning "pitch creating" or "pitch producing" (referring to coniferous or resinous trees). The Latin equivalent is claimed by some to be originally gwitu-men (pertaining to pitch), and by others, pixtumens (exuding or bubbling pitch), which was subsequently shortened to bitumen, thence passing via French into English. From the same root is derived the Anglo-Saxon word cwidu (mastix), the German word Kitt (cement or mastic) and the old Norse word kvada.
In British English, "bitumen" is used instead of "asphalt". The word "asphalt" is instead used to refer to asphalt concrete, a mixture of construction aggregate and asphalt itself (also called "tarmac" in common parlance). Bitumen mixed with clay was usually called "asphaltum", but the term is less commonly used today.
In Australian English, "bitumen" is often used as the generic term for road surfaces.
In American English, "asphalt" is equivalent to the British "bitumen". However, "asphalt" is also commonly used as a shortened form of "asphalt concrete" (therefore equivalent to the British "asphalt" or "tarmac").
In Canadian English, the word "bitumen" is used to refer to the vast Canadian deposits of extremely heavy crude oil, while "asphalt" is used for the oil refinery product. Diluted bitumen (diluted with naphtha to make it flow in pipelines) is known as "dilbit" in the Canadian petroleum industry, while bitumen "upgraded" to synthetic crude oil is known as "syncrude", and syncrude blended with bitumen is called "synbit".
"Bitumen" is still the preferred geological term for naturally occurring deposits of the solid or semi-solid form of petroleum. "Bituminous rock" is a form of sandstone impregnated with bitumen. The tar sands of Alberta, Canada are a similar material.
Neither of the terms "asphalt" or "bitumen" should be confused with tar or coal tars.[further explanation needed]See also: Asphaltene
The components of asphalt include four main classes of compounds:
The naphthene aromatics and polar aromatics are typically the majority components. Most natural bitumens also contain organosulfur compounds, resulting in an overall sulfur content of up to 4%. Nickel and vanadium are found at <10 parts per million, as is typical of some petroleum.
The substance is soluble in carbon disulfide. It is commonly modelled as a colloid, with asphaltenes as the dispersed phase and maltenes as the continuous phase. "It is almost impossible to separate and identify all the different molecules of asphalt, because the number of molecules with different chemical structure is extremely large".
Asphalt may be confused with coal tar, which is a visually similar black, thermoplastic material produced by the destructive distillation of coal. During the early and mid-20th century, when town gas was produced, coal tar was a readily available byproduct and extensively used as the binder for road aggregates. The addition of coal tar to macadam roads led to the word "tarmac", which is now used in common parlance to refer to road-making materials. However, since the 1970s, when natural gas succeeded town gas, asphalt has completely overtaken the use of coal tar in these applications. Other examples of this confusion include the La Brea Tar Pits and the Canadian oil sands, both of which actually contain natural bitumen rather than tar. "Pitch" is another term sometimes informally used at times to refer to asphalt, as in Pitch Lake.Bituminous outcrop of the Puy de la Poix, Clermont-Ferrand, France
The majority of asphalt used commercially is obtained from petroleum. Nonetheless, large amounts of asphalt occur in concentrated form in nature. Naturally occurring deposits of bitumen are formed from the remains of ancient, microscopic algae (diatoms) and other once-living things. These remains were deposited in the mud on the bottom of the ocean or lake where the organisms lived. Under the heat (above 50 °C) and pressure of burial deep in the earth, the remains were transformed into materials such as bitumen, kerogen, or petroleum.
Natural deposits of bitumen include lakes such as the Pitch Lake in Trinidad and Tobago and Lake Bermudez in Venezuela. Natural seeps occur in the La Brea Tar Pits and in the Dead Sea.
Bitumen also occurs in unconsolidated sandstones known as "oil sands" in Alberta, Canada, and the similar "tar sands" in Utah, US. The Canadian province of Alberta has most of the world's reserves, in three huge deposits covering 142,000 square kilometres (55,000 sq mi), an area larger than England or New York state. These bituminous sands contain 166 billion barrels (26.4×10^9 m3) of commercially established oil reserves, giving Canada the third largest oil reserves in the world. Although historically it was used without refining to pave roads, nearly all of the output is now used as raw material for oil refineries in Canada and the United States.
The world's largest deposit of natural bitumen, known as the Athabasca oil sands, is located in the McMurray Formation of Northern Alberta. This formation is from the early Cretaceous, and is composed of numerous lenses of oil-bearing sand with up to 20% oil. Isotopic studies show the oil deposits to be about 110 million years old. Two smaller but still very large formations occur in the Peace River oil sands and the Cold Lake oil sands, to the west and southeast of the Athabasca oil sands, respectively. Of the Alberta deposits, only parts of the Athabasca oil sands are shallow enough to be suitable for surface mining. The other 80% has to be produced by oil wells using enhanced oil recovery techniques like steam-assisted gravity drainage.
Much smaller heavy oil or bitumen deposits also occur in the Uinta Basin in Utah, US. The Tar Sand Triangle deposit, for example, is roughly 6% bitumen.
Bitumen may occur in hydrothermal veins. An example of this is within the Uinta Basin of Utah, in the US, where there is a swarm of laterally and vertically extensive veins composed of a solid hydrocarbon termed Gilsonite. These veins formed by the polymerization and solidification of hydrocarbons that were mobilized from the deeper oil shales of the Green River Formation during burial and diagenesis.
Bitumen is similar to the organic matter in carbonaceous meteorites. However, detailed studies have shown these materials to be distinct. The vast Alberta bitumen resources are considered to have started out as living material from marine plants and animals, mainly algae, that died millions of years ago when an ancient ocean covered Alberta. They were covered by mud, buried deeply over time, and gently cooked into oil by geothermal heat at a temperature of 50 to 150 °C (120 to 300 °F). Due to pressure from the rising of the Rocky Mountains in southwestern Alberta, 80 to 55 million years ago, the oil was driven northeast hundreds of kilometres and trapped into underground sand deposits left behind by ancient river beds and ocean beaches, thus forming the oil sands.
The use of natural bitumen for waterproofing, and as an adhesive dates at least to the fifth millennium BC, with a crop storage basket discovered in Mehrgarh, of the Indus Valley Civilization, lined with it. By the 3rd millennia BC refined rock asphalt was in use, in the region, and was used to waterproof the Great Bath, Mohenjo-daro.
In the ancient Middle East, the Sumerians used natural bitumen deposits for mortar between bricks and stones, to cement parts of carvings, such as eyes, into place, for ship caulking, and for waterproofing. The Greek historian Herodotus said hot bitumen was used as mortar in the walls of Babylon.
The 1 kilometre (0.62 mi) long Euphrates Tunnel beneath the river Euphrates at Babylon in the time of Queen Semiramis (ca. 800 BC) was reportedly constructed of burnt bricks covered with bitumen as a waterproofing agent.
Bitumen was used by ancient Egyptians to embalm mummies. The Persian word for asphalt is moom, which is related to the English word mummy. The Egyptians' primary source of bitumen was the Dead Sea, which the Romans knew as Palus Asphaltites (Asphalt Lake).
Approximately 40 AD, Dioscorides described the Dead Sea material as Judaicum bitumen, and noted other places in the region where it could be found. The Sidon bitumen is thought to refer to material found at Hasbeya. Pliny refers also to bitumen being found in Epirus. It was a valuable strategic resource, the object of the first known battle for a hydrocarbon deposit—between the Seleucids and the Nabateans in 312 BC.
In the ancient Far East, natural bitumen was slowly boiled to get rid of the higher fractions, leaving a thermoplastic material of higher molecular weight that when layered on objects became quite hard upon cooling. This was used to cover objects that needed waterproofing, such as scabbards and other items. Statuettes of household deities were also cast with this type of material in Japan, and probably also in China.
In North America, archaeological recovery has indicated bitumen was sometimes used to adhere stone projectile points to wooden shafts. In Canada, aboriginal people used bitumen seeping out of the banks of the Athabasca and other rivers to waterproof birch bark canoes, and also heated it in smudge pots to ward off mosquitoes in the summer.
In 1553, Pierre Belon described in his work Observations that pissasphalto, a mixture of pitch and bitumen, was used in the Republic of Ragusa (now Dubrovnik, Croatia) for tarring of ships.
An 1838 edition of Mechanics Magazine cites an early use of asphalt in France. A pamphlet dated 1621, by "a certain Monsieur d'Eyrinys, states that he had discovered the existence (of asphaltum) in large quantities in the vicinity of Neufchatel", and that he proposed to use it in a variety of ways – "principally in the construction of air-proof granaries, and in protecting, by means of the arches, the water-courses in the city of Paris from the intrusion of dirt and filth", which at that time made the water unusable. "He expatiates also on the excellence of this material for forming level and durable terraces" in palaces, "the notion of forming such terraces in the streets not one likely to cross the brain of a Parisian of that generation".
But the substance was generally neglected in France until the revolution of 1830. In the 1830s there was a surge of interest, and asphalt became widely used "for pavements, flat roofs, and the lining of cisterns, and in England, some use of it had been made of it for similar purposes". Its rise in Europe was "a sudden phenomenon", after natural deposits were found "in France at Osbann (Bas-Rhin), the Parc (Ain) and the Puy-de-la-Poix (Puy-de-Dôme)", although it could also be made artificially. One of the earliest uses in France was the laying of about 24,000 square yards of Seyssel asphalt at the Place de la Concorde in 1835.
Among the earlier uses of bitumen in the United Kingdom was for etching. William Salmon's Polygraphice (1673) provides a recipe for varnish used in etching, consisting of three ounces of virgin wax, two ounces of mastic, and one ounce of asphaltum. By the fifth edition in 1685, he had included more asphaltum recipes from other sources.
The first British patent for the use of asphalt was "Cassell's patent asphalte or bitumen" in 1834. Then on 25 November 1837, Richard Tappin Claridge patented the use of Seyssel asphalt (patent #7849), for use in asphalte pavement, having seen it employed in France and Belgium when visiting with Frederick Walter Simms, who worked with him on the introduction of asphalt to Britain. Dr T. Lamb Phipson writes that his father, Samuel Ryland Phipson, a friend of Claridge, was also "instrumental in introducing the asphalte pavement (in 1836)". Indeed, mastic pavements had been previously employed at Vauxhall by a competitor of Claridge, but without success.
Claridge obtained a patent in Scotland on 27 March 1838, and obtained a patent in Ireland on 23 April 1838. In 1851, extensions for the 1837 patent and for both 1838 patents were sought by the trustees of a company previously formed by Claridge. Claridge's Patent Asphalte Company—formed in 1838 for the purpose of introducing to Britain "Asphalte in its natural state from the mine at Pyrimont Seysell in France",—"laid one of the first asphalt pavements in Whitehall". Trials were made of the pavement in 1838 on the footway in Whitehall, the stable at Knightsbridge Barracks, "and subsequently on the space at the bottom of the steps leading from Waterloo Place to St. James Park". "The formation in 1838 of Claridge's Patent Asphalte Company (with a distinguished list of aristocratic patrons, and Marc and Isambard Brunel as, respectively, a trustee and consulting engineer), gave an enormous impetus to the development of a British asphalt industry". "By the end of 1838, at least two other companies, Robinson's and the Bastenne company, were in production", with asphalt being laid as paving at Brighton, Herne Bay, Canterbury, Kensington, the Strand, and a large floor area in Bunhill-row, while meantime Claridge's Whitehall paving "continue(d) in good order".
In 1838, there was a flurry of entrepreneurial activity involving asphalt, which had uses beyond paving. For example, asphalt could also be used for flooring, damp proofing in buildings, and for waterproofing of various types of pools and baths, both of which were also proliferating in the 19th century. On the London stockmarket, there were various claims as to the exclusivity of asphalt quality from France, Germany and England. And numerous patents were granted in France, with similar numbers of patent applications being denied in England due to their similarity to each other. In England, "Claridge's was the type most used in the 1840s and 50s".
In 1914, Claridge's Company entered into a joint venture to produce tar-bound macadam, with materials manufactured through a subsidiary company called Clarmac Roads Ltd. Two products resulted, namely Clarmac, and Clarphalte, with the former being manufactured by Clarmac Roads and the latter by Claridge's Patent Asphalte Co., although Clarmac was more widely used.[note 1] However, the First World War ruined the Clarmac Company, which entered into liquidation in 1915. The failure of Clarmac Roads Ltd had a flow-on effect to Claridge's Company, which was itself compulsorily wound up, ceasing operations in 1917, having invested a substantial amount of funds into the new venture, both at the outset and in a subsequent attempt to save the Clarmac Company.
The first use of bitumen in the New World was by indigenous peoples. On the west coast, as early as the 13th century, the Tongva, Luiseño and Chumash peoples collected the naturally occurring bitumen that seeped to the surface above underlying petroleum deposits. All three groups used the substance as an adhesive. It is found on many different artifacts of tools and ceremonial items. For example, it was used on rattles to adhere gourds or turtle shells to rattle handles. It was also used in decorations. Small round shell beads were often set in asphaltum to provide decorations. It was used as a sealant on baskets to make them watertight for carrying water, possibly poisoning those who drank the water. Asphalt was used also to seal the planks on ocean-going canoes.
Asphalt was first used to pave streets in the 1870s. At first naturally occurring "bituminous rock" was used, such as at Ritchie Mines in Macfarlan in Ritchie County, West Virginia from 1852 to 1873. In 1876, asphalt-based paving was used to pave Pennsylvania Avenue in Washington DC, in time for the celebration of the national centennial. In the horse-drawn era, streets were unpaved and covered with dirt or gravel. However, that produced uneven wear, opened new hazards for pedestrians and made for dangerous potholes for bicycles and for motor vehicles. Manhattan alone had 130,000 horses in 1900, pulling streetcars, wagons, and carriages, and leaving their waste behind. They were not fast, and pedestrians could dodge and scramble their way across the crowded streets. Small towns continued to rely on dirt and gravel, but larger cities wanted much better streets. They looked to wood or granite blocks by the 1850s. In 1890, a third of Chicago's 2000 miles of streets were paved, chiefly with wooden blocks, which gave better traction than mud. Brick surfacing was a good compromise, but even better was asphalt paving, which was easy to install and to cut through to get at sewers. With London and Paris serving as models, Washington laid 400,000 square yards of asphalt paving by 1882; it became the model for Buffalo, Philadelphia and elsewhere. By the end of the century, American cities boasted 30 million square yards of asphalt paving, well ahead of brick. The streets became faster and more dangerous so electric traffic lights were installed. Electric trolleys (at 12 miles per hour) became the main transportation service for middle class shoppers and office workers until they bought automobiles after 1945 and commuted from more distant suburbs in privacy and comfort on asphalt highways.See also: Bitumount and History of the petroleum industry in Canada (oil sands and heavy oil)
Canada has the world's largest deposit of natural bitumen in the Athabasca oil sands, and Canadian First Nations along the Athabasca River had long used it to waterproof their canoes. In 1719, a Cree named Wa-Pa-Su brought a sample for trade to Henry Kelsey of the Hudson’s Bay Company, who was the first recorded European to see it. However, it wasn't until 1787 that fur trader and explorer Alexander MacKenzie saw the Athabasca oil sands and said, "At about 24 miles from the fork (of the Athabasca and Clearwater Rivers) are some bituminous fountains into which a pole of 20 feet long may be inserted without the least resistance."
The value of the deposit was obvious from the start, but the means of extracting the bitumen was not. The nearest town, Fort McMurray, Alberta, was a small fur trading post, other markets were far away, and transportation costs were too high to ship the raw bituminous sand for paving. In 1915, Sidney Ells of the Federal Mines Branch experimented with separation techniques and used the product to pave 600 feet of road in Edmonton, Alberta. Other roads in Alberta were paved with material extracted from oil sands, but it was generally not economic. During the 1920s Dr. Karl A. Clark of the Alberta Research Council patented a hot water oil separation process and entrepreneur Robert C. Fitzsimmons built the Bitumount oil separation plant, which between 1925 and 1958 produced up to 300 barrels (50 m3) per day of bitumen using Dr. Clark's method. Most of the bitumen was used for waterproofing roofs, but other uses included fuels, lubrication oils, printers ink, medicines, rust- and acid-proof paints, fireproof roofing, street paving, patent leather, and fence post preservatives. Eventually Fitzsimmons ran out of money and the plant was taken over by the Alberta government. Today the Bitumount plant is a Provincial Historic Site.
Bitumen was used in early photographic technology. In 1826 or 1827, it was used by French scientist Joseph Nicéphore Niépce to make the oldest surviving photograph from nature. The bitumen was thinly coated onto a pewter plate which was then exposed in a camera. Exposure to light hardened the bitumen and made it insoluble, so that when it was subsequently rinsed with a solvent only the sufficiently light-struck areas remained. Many hours of exposure in the camera were required, making bitumen impractical for ordinary photography, but from the 1850s to the 1920s it was in common use as a photoresist in the production of printing plates for various photomechanical printing processes.
Bitumen was the nemesis of many artists during the 19th century. Although widely used for a time, it ultimately proved unstable for use in oil painting, especially when mixed with the most common diluents, such as linseed oil, varnish and turpentine. Unless thoroughly diluted, bitumen never fully solidifies and will in time corrupt the other pigments with which it comes into contact. The use of bitumen as a glaze to set in shadow or mixed with other colors to render a darker tone resulted in the eventual deterioration of many paintings, for instance those of Delacroix. Perhaps the most famous example of the destructiveness of bitumen is Théodore Géricault's Raft of the Medusa (1818–1819), where his use of bitumen caused the brilliant colors to degenerate into dark greens and blacks and the paint and canvas to buckle.
The vast majority of refined asphalt is used in construction: primarily as a constituent of products used in paving and roofing applications. According to the requirements of the end use, asphalt is produced to specification. This is achieved either by refining or blending. It is estimated that the current world use of asphalt is approximately 102 million tonnes per year. Approximately 85% of all the asphalt produced is used as the binder in asphalt concrete for roads. It is also used in other paved areas such as airport runways, car parks and footways. Typically, the production of asphalt concrete involves mixing fine and coarse aggregates such as sand, gravel and crushed rock with asphalt, which acts as the binding agent. Other materials, such as recycled polymers (e.g., rubber tyres), may be added to the asphalt to modify its properties according to the application for which the asphalt is ultimately intended.
A further 10% of global asphalt production is used in roofing applications, where its waterproofing qualities are invaluable. The remaining 5% of asphalt is used mainly for sealing and insulating purposes in a variety of building materials, such as pipe coatings, carpet tile backing and paint. Asphalt is applied in the construction and maintenance of many structures, systems, and components, such as the following:Main article: Asphalt concrete
The largest use of asphalt is for making asphalt concrete for road surfaces; this accounts for approximately 85% of the asphalt consumed in the United States. Asphalt concrete pavement mixes are typically composed of 5% asphalt cement and 95% aggregates (stone, sand, and gravel). Due to its highly viscous nature, asphalt cement must be heated so it can be mixed with the aggregates at the asphalt mixing facility. The temperature required varies depending upon characteristics of the asphalt and the aggregates, but warm-mix asphalt technologies allow producers to reduce the temperature required. There are about 4,000 asphalt concrete mixing plants in the US, and a similar number in Europe.
When maintenance is performed on asphalt pavements, such as milling to remove a worn or damaged surface, the removed material can be returned to a facility for processing into new pavement mixtures. The asphalt in the removed material can be reactivated and put back to use in new pavement mixes. With some 95% of paved roads being constructed of or surfaced with asphalt, a substantial amount of asphalt pavement material is reclaimed each year. According to industry surveys conducted annually by the Federal Highway Administration and the National Asphalt Pavement Association, more than 99% of the asphalt removed each year from road surfaces during widening and resurfacing projects is reused as part of new pavements, roadbeds, shoulders and embankments.
Asphalt concrete paving is widely used in airports around the world. Due to the sturdiness and ability to be repaired quickly, it is widely used for runways.Further information: Fibre mastic asphalt
Mastic asphalt is a type of asphalt that differs from dense graded asphalt (asphalt concrete) in that it has a higher asphalt (binder) content, usually around 7–10% of the whole aggregate mix, as opposed to rolled asphalt concrete, which has only around 5% asphalt. This thermoplastic substance is widely used in the building industry for waterproofing flat roofs and tanking underground. Mastic asphalt is heated to a temperature of 210 °C (410 °F) and is spread in layers to form an impervious barrier about 20 millimeters (0.8 inches) thick.
A number of technologies allow asphalt to be mixed at much lower temperatures. These involve mixing with petroleum solvents to form "cutbacks" with reduced melting point or mixing with water to turn the asphalt into an emulsion. Asphalt emulsions contain up to 70% asphalt and typically less than 1.5% chemical additives. There are two main types of emulsions with different affinity for aggregates, cationic and anionic. Asphalt emulsions are used in a wide variety of applications. Chipseal involves spraying the road surface with asphalt emulsion followed by a layer of crushed rock, gravel or crushed slag. Slurry seal involves the creation of a mixture of asphalt emulsion and fine crushed aggregate that is spread on the surface of a road. Cold-mixed asphalt can also be made from asphalt emulsion to create pavements similar to hot-mixed asphalt, several inches in depth, and asphalt emulsions are also blended into recycled hot-mix asphalt to create low-cost pavements.Main article: Synthetic crude oil See also: Petroleum production in Canada
Synthetic crude oil, also known as syncrude, is the output from a bitumen upgrader facility used in connection with oil sand production in Canada. Bituminous sands are mined using enormous (100 ton capacity) power shovels and loaded into even larger (400 ton capacity) dump trucks for movement to an upgrading facility. The process used to extract the bitumen from the sand is a hot water process originally developed by Dr. Karl Clark of the University of Alberta during the 1920s. After extraction from the sand, the bitumen is fed into a bitumen upgrader which converts it into a light crude oil equivalent. This synthetic substance is fluid enough to be transferred through conventional oil pipelines and can be fed into conventional oil refineries without any further treatment. By 2015 Canadian bitumen upgraders were producing over 1 million barrels (160×10^3 m3) per day of synthetic crude oil, of which 75% was exported to oil refineries in the United States.
In Alberta, five bitumen upgraders produce synthetic crude oil and a variety of other products: The Suncor Energy upgrader near Fort McMurray, Alberta produces synthetic crude oil plus diesel fuel; the Syncrude Canada, Canadian Natural Resources, and Nexen upgraders near Fort McMurray produce synthetic crude oil; and the Shell Scotford Upgrader near Edmonton produces synthetic crude oil plus an intermediate feedstock for the nearby Shell Oil Refinery. A sixth upgrader, under construction in 2015 near Redwater, Alberta, will upgrade half of its crude bitumen directly to diesel fuel, with the remainder of the output being sold as feedstock to nearby oil refineries and petrochemical plants.See also: Western Canadian Select
Canadian bitumen does not differ substantially from oils such as Venezuelan extra-heavy and Mexican heavy oil in chemical composition, and the real difficulty is moving the extremely viscous bitumen through oil pipelines to the refinery. Many modern oil refineries are extremely sophisticated and can process non-upgraded bitumen directly into products such as gasoline, diesel fuel, and refined asphalt without any preprocessing. This is particularly common in areas such as the US Gulf coast, where refineries were designed to process Venezuelan and Mexican oil, and in areas such as the US Midwest where refineries were rebuilt to process heavy oil as domestic light oil production declined. Given the choice, such heavy oil refineries usually prefer to buy bitumen rather than synthetic oil because the cost is lower, and in some cases because they prefer to produce more diesel fuel and less gasoline. By 2015 Canadian production and exports of non-upgraded bitumen exceeded that of synthetic crude oil at over 1.3 million barrels (210×10^3 m3) per day, of which about 65% was exported to the United States.
Because of the difficulty of moving crude bitumen through pipelines, non-upgraded bitumen is usually diluted with natural-gas condensate in a form called dilbit or with synthetic crude oil, called synbit. However, to meet international competition, much non-upgraded bitumen is now sold as a blend of multiple grades of bitumen, conventional crude oil, synthetic crude oil, and condensate in a standardized benchmark product such as Western Canadian Select. This sour, heavy crude oil blend is designed to have uniform refining characteristics to compete with internationally marketed heavy oils such as Mexican Mayan or Arabian Dubai Crude.
Asphalt was used starting in the 1960s as an hydrophobic matrix aiming to encapsulate radioactive waste such as medium-activity salts (mainly soluble sodium nitrate and sodium sulfate) produced by the reprocessing of spent nuclear fuels or radioactive sludges from sedimentation ponds. Bituminised radioactive waste containing highly radiotoxic alpha-emitting transuranic elements from nuclear reprocessing plants have been produced at industrial scale in France, Belgium and Japan, but this type of waste conditioning has been abandoned because operational safety issues (risks of fire, as occurred in a bituminisation plant at Tokai Works in Japan) and long-term stability problems related to their geological disposal in deep rock formations. One of the main problem is the swelling of asphalt exposed to radiation and to water. Asphalt swelling is first induced by radiation because of the presence of hydrogen gas bubbles generated by alpha and gamma radiolysis. A second mechanism is the matrix swelling when the encapsulated hygroscopic salts exposed to water or moisture start to rehydrate and to dissolve. The high concentration of salt in the pore solution inside the bituminised matrix is then responsible for osmotic effects inside the bituminised matrix. The water moves in the direction of the concentrated salts, the asphalt acting as a semi-permeable membrane. This also causes the matrix to swell. The swelling pressure due to osmotic effect under constant volume can be as high as 200 bar. If not properly managed, this high pressure can cause fractures in the near field of a disposal gallery of bituminised medium-level waste. When the bituminised matrix has been altered by swelling, encapsulated radionuclides are easily leached by the contact of ground water and released in the geosphere. The high ionic strength of the concentrated saline solution also favours the migration of radionuclides in clay host rocks. The presence of chemically reactive nitrate can also affect the redox conditions prevailing in the host rock by establishing oxidizing conditions, preventing the reduction of redox-sensitive radionuclides. Under their higher valences, radionuclides of elements such as selenium, technetium, uranium, neptunium and plutonium have a higher solubility and are also often present in water as non-retarded anions. This makes the disposal of medium-level bituminised waste very challenging.
Different type of asphalt have been used: blown bitumen (partly oxidized with air oxygen at high temperature after distillation, and harder) and direct distillation bitumen (softer). Blown bitumens like Mexphalte, with a high content of saturated hydrocarbons, are more easily biodegraded by microorganisms than direct distillation bitumen, with a low content of saturated hydrocarbons and a high content of aromatic hydrocarbons.
Concrete encapsulation of radwaste is presently considered a safer alternative by the nuclear industry and the waste management organisations.
Roofing shingles account for most of the remaining asphalt consumption. Other uses include cattle sprays, fence-post treatments, and waterproofing for fabrics. Asphalt is used to make Japan black, a lacquer known especially for its use on iron and steel, and it is also used in paint and marker inks by some exterior paint supply companies to increase the weather resistance and permanence of the paint or ink, and to make the color darker. Asphalt is also used to seal some alkaline batteries during the manufacturing process.Typical asphalt plant for making asphalt
About 40,000,000 tons were produced in 1984.[needs update] It is obtained as the "heavy" (i.e., difficult to distill) fraction. Material with a boiling point greater than around 500 °C is considered asphalt. Vacuum distillation separates it from the other components in crude oil (such as naphtha, gasoline and diesel). The resulting material is typically further treated to extract small but valuable amounts of lubricants and to adjust the properties of the material to suit applications. In a de-asphalting unit, the crude asphalt is treated with either propane or butane in a supercritical phase to extract the lighter molecules, which are then separated. Further processing is possible by "blowing" the product: namely reacting it with oxygen. This step makes the product harder and more viscous.
Asphalt is typically stored and transported at temperatures around 150 °C (302 °F). Sometimes diesel oil or kerosene are mixed in before shipping to retain liquidity; upon delivery, these lighter materials are separated out of the mixture. This mixture is often called "bitumen feedstock", or BFS. Some dump trucks route the hot engine exhaust through pipes in the dump body to keep the material warm. The backs of tippers carrying asphalt, as well as some handling equipment, are also commonly sprayed with a releasing agent before filling to aid release. Diesel oil is no longer used as a release agent due to environmental concerns.Main article: Oil sands
Naturally occurring crude bitumen impregnated in sedimentary rock is the prime feed stock for petroleum production from "oil sands", currently under development in Alberta, Canada. Canada has most of the world's supply of natural bitumen, covering 140,000 square kilometres (an area larger than England), giving it the second-largest proven oil reserves in the world. The Athabasca oil sands are the largest bitumen deposit in Canada and the only one accessible to surface mining, although recent technological breakthroughs have resulted in deeper deposits becoming producible by in situ methods. Because of oil price increases after 2003, producing bitumen became highly profitable, but as a result of the decline after 2014 it became uneconomic to build new plants again. By 2014, Canadian crude bitumen production averaged about 2.3 million barrels (370,000 m3) per day and was projected to rise to 4.4 million barrels (700,000 m3) per day by 2020. The total amount of crude bitumen in Alberta that could be extracted is estimated to be about 310 billion barrels (50×10^9 m3), which at a rate of 4,400,000 barrels per day (700,000 m3/d) would last about 200 years.Main articles: Peak oil, Global warming, and Bioasphalt
Although uncompetitive economically, asphalt can be made from nonpetroleum-based renewable resources such as sugar, molasses and rice, corn and potato starches. Asphalt can also be made from waste material by fractional distillation of used motor oil, which is sometimes otherwise disposed of by burning or dumping into landfills. Use of motor oil may cause premature cracking in colder climates, resulting in roads that need to be repaved more frequently.
Nonpetroleum-based asphalt binders can be made light-colored. Lighter-colored roads absorb less heat from solar radiation, reducing their contribution to the urban heat island effect. Parking lots that use asphalt alternatives are called green parking lots.
Selenizza is a naturally occurring solid hydrocarbon bitumen found in native deposits in Selenice, in Albania, the only European asphalt mine still in use. The bitumen is found in the form of veins, filling cracks in a more or less horizontal direction. The bitumen content varies from 83% to 92% (soluble in carbon disulphide), with a penetration value near to zero and a softening point (ring and ball) around 120 °C. The insoluble matter, consisting mainly of silica ore, ranges from 8% to 17%.
Albanian bitumen extraction has a long history and was practiced in an organized way by the Romans. After centuries of silence, the first mentions of Albanian bitumen appeared only in 1868, when the Frenchman Coquand published the first geological description of the deposits of Albanian bitumen. In 1875, the exploitation rights were granted to the Ottoman government and in 1912, they were transferred to the Italian company Simsa. Since 1945, the mine was exploited by the Albanian government and from 2001 to date, the management passed to a French company, which organized the mining process for the manufacture of the natural bitumen on an industrial scale.
Today the mine is predominantly exploited in an open pit quarry but several of the many underground mines (deep and extending over several km) still remain viable. Selenizza is produced primarily in granular form, after melting the bitumen pieces selected in the mine.
Selenizza is mainly used as an additive in the road construction sector. It is mixed with traditional asphalt to improve both the viscoelastic properties and the resistance to ageing. It may be blended with the hot asphalt in tanks, but its granular form allows it to be fed in the mixer or in the recycling ring of normal asphalt plants. Other typical applications include the production of mastic asphalts for sidewalks, bridges, car-parks and urban roads as well as drilling fluid additives for the oil and gas industry. Selenizza is available in powder or in granular material of various particle sizes and is packaged in sacks or in thermal fusible polyethylene bags.
A life-cycle assessment study of the natural selenizza compared with petroleum asphalt has shown that the environmental impact of the selenizza is about half the impact of the road asphalt produced in oil refineries in terms of carbon dioxide emission.
People can be exposed to asphalt in the workplace by breathing in fumes or skin absorption. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit of 5 mg/m3 over a 15-minute period.
Asphalt is basically an inert material that must be heated or diluted to a point where it becomes workable for the production of materials for paving, roofing, and other applications. In examining the potential health hazards associated with asphalt, the International Agency for Research on Cancer (IARC) determined that it is the application parameters, predominantly temperature, that affect occupational exposure and the potential bioavailable carcinogenic hazard/risk of the asphalt emissions. In particular, temperatures greater than 199 °C (390 °F), were shown to produce a greater exposure risk than when asphalt was heated to lower temperatures, such as those typically used in asphalt pavement mix production and placement. IARC has classified asphalt as a Class 2B possible carcinogen.An asphalt mixing plant for hot aggregate
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Toll roadA diagram illustrating traffic movements in the interchange Plan of rejected diverging diamond interchange in Findlay, Ohio
A diverging diamond interchange (DDI), also called a double crossover diamond interchange (DCD), is a type of diamond interchange in which the two directions of traffic on the non-freeway road cross to the opposite side on both sides of the bridge at the freeway. It is unusual in that it requires traffic on the freeway overpass (or underpass) to briefly drive on the opposite side of the road from what is customary for the jurisdiction. The crossover "X" sections can either be traffic-light intersections or one-side overpasses to travel above the opposite lanes without stopping, to allow nonstop traffic flow when relatively sparse traffic.
Like the continuous flow intersection, the diverging diamond interchange allows for two-phase operation at all signalized intersections within the interchange. This is a significant improvement in safety, since no long turns (e.g. left turns where traffic drives on the right side of the road) must clear opposing traffic and all movements are discrete, with most controlled by traffic signals. Its at-grade variant can be seen as a two-leg continuous flow intersection.
Additionally, the design can improve the efficiency of an interchange, as the lost time for various phases in the cycle can be redistributed as green time—there are only two clearance intervals (the time for traffic signals to change from green to yellow to red) instead of the six or more found in other interchange designs.
A diverging diamond can be constructed for limited cost, at an existing straight-line bridge, by building crisscross intersections outside the bridge ramps to switch traffic lanes before entering the bridge. The switchover lanes, each with 2 side ramps, introduce a new risk of drivers turning onto an empty, wrong, do-not-enter, exit-lane and driving wrongway down a freeway exit ramp to confront high-speed, oncoming traffic. Studies have analyzed various roadsigns to reduce similar driver errors.
Diverging diamond roads have been used in France since the 1970s. However, the diverging diamond interchange was listed by Popular Science magazine as one of the best innovations in 2009 (engineering category) in "Best of What's New 2009".Pictures from the first diverging diamond interchange in the United States, in Springfield, Missouri
Top left: Traffic enters the interchange along Missouri Route 13
Top right: Traffic crosses over to the left side of the road
Bottom left: Traffic crosses over Interstate 44
Bottom right:Traffic crosses back over to the right side of the road. Southbound approach to the I-44/Route 13 interchange in Springfield
Prior to 2009 the only known diverging diamond interchanges were in France in the communities of Versailles, Le Perreux-sur-Marne (A4 at N486) and Seclin, all built in the 1970s. (The ramps of the first two have been reconfigured to accommodate ramps of other interchanges, but they continue to function as diverging diamond interchanges.)
Despite the fact that such interchanges already existed, the idea for the DDI was "reinvented" around 2000, inspired by the former "synchronized split-phasing" type freeway-to-freeway interchange between Interstate 95 and I-695 north of Baltimore.
In 2005, the Ohio Department of Transportation (ODOT) considered reconfiguring the existing interchange on Interstate 75 at U.S. Route 224 and State Route 15 west of Findlay as a diverging diamond interchange to improve traffic flow. Had it been constructed, it would have been the first DDI in the United States. By 2006, ODOT had reconsidered, instead adding lanes to the existing overpass.
The Missouri Department of Transportation was the first US agency to construct one, in Springfield at the junction between I-44 and Missouri Route 13 (at 37°15′01″N 93°18′39″W / 37.2503°N 93.3107°W / 37.2503; -93.3107 (Springfield, Missouri diverging diamond interchange)). Construction began the week of January 12, 2009, and the interchange opened on June 21, 2009. This interchange was a conversion of an existing standard diamond interchange, and used the existing bridge.
The first interchange in Canada opened on August 13, 2017 at Macleod Trail and 162 Avenue South in Calgary, Alberta.
The interchange in Seclin (at 50°32′41″N 3°3′21″E / 50.54472°N 3.05583°E / 50.54472; 3.05583) between the A1 and Route d'Avelin was somewhat more specialized than in the diagram at right: eastbound traffic on Route d'Avelin intending to enter the A1 northbound must keep left and cross the northernmost bridge before turning left to proceed north onto A1; eastbound traffic continuing east on Route d'Avelin must select a single center lane, merge with A1 traffic that is exiting to proceed east, and cross a center bridge. All westbound traffic that is continuing west or turning south onto A1 uses the southernmost bridge.
Additional research was conducted by a partnership of the Virginia Polytechnic Institute and State University and the Turner-Fairbank Highway Research Center and published by Ohio Section of the Institute of Transportation Engineers. The Federal Highway Administration released a publication titled "Alternative Intersections/Interchanges: Informational Report (AIIR)"  with a chapter dedicated to this design.
As of January 19, 2018, 106 DDIs were operational across the world including:3D computer generated DCMI DCMI traffic flow patterns
A free-flowing interchange variant, patented in 2015, has received recent attention. Called the double crossover merging interchange (DCMI), it includes elements from the diverging diamond interchange, the tight diamond interchange, and the stack interchange. It eliminates the disadvantages of weaving and of merging into the outside lane from which the standard DDI variation suffers. As of 2016, no such interchanges have been constructed.
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