For other uses, see Asphalt (disambiguation). Note: The terms bitumen and asphalt are mostly interchangeable, Pavement Maintenance in JHB 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 primary use (70%) of asphalt Asphalt Driveway Paving Contractor 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”. Pavement Maintenance 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”. Asphalt Maintenance Company 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”.
Pavement Maintenance in JHB ?Boulevard Haussmann in Paris, France. The Straße des 17. Juni in Berlin, Germany.
A boulevard (French, from Dutch: Bolwerk – bulwark, meaning bastion), often abbreviated Blvd, is a type of large road, usually running through a city.
In modern American usage it often means a wide, multi-lane arterial thoroughfare, often divided with a median down the centre, and perhaps with roadways along each side designed as slow travel and parking lanes and for bicycle and pedestrian usage, often with an above-average quality of landscaping and scenery.
Phnom Penh has numerous boulevards scattered throughout the city. Norodom Boulevard, Sisowath Boulevard, Monivong Boulevard, and Sothearos Boulevard are the most famous.Marine Drive, Mumbai View of Rajpath from Raisina Hill with India Gate at its terminal Keshavarz Boulevard of Tehran, Iran in mid 1970s
In Iran, "Boulevard" is generally defined as a wide road surrounded by trees in sides and divided by a green space line including grass, trees or buxuses in the middle. There are many boulevards in Iran. One of the most famous one is Keshavarz Boulevard in Tehran which is usually referred to as "The Boulevard". Isfahan has also a historical boulevard which is called Chaharbagh Boulevard.
Tel Aviv, was originally designed along the guidelines set out by architect Sir Patrick Geddes. Geddes designed a green or garden ring of boulevards surrounding the central city, which still exists today and continues to characterize Tel Aviv. One of the most famous and busy streets in the city is Rothschild Boulevard.Roxas Boulevard in Manila, Philippines.
Roxas Boulevard is a major boulevard in Metro Manila, Philippines. The boulevard, which runs along the shores of Manila Bay, is popular for its view of Manila's famous sunsets and stretch of coconut trees. The boulevard is an eight-lane major arterial road designated as Radial Road 1 that connects the center of Manila with Pasay and Parañaque.
Other boulevards in Metro Manila include the Shaw Boulevard, España Boulevard, Pedro Tuazon Boulevard and Quezon Boulevard. Not all boulevards in the Philippines have ornamentation, or slow lanes, like the Aurora Boulevard and E. Rodriguez Sr. Boulevard, which have no ornamentation at all.
Osmeña Boulevard is a boulevard in Cebu City, the Philippines' second city. It is Cebu's most important street and is its primary ceremonial avenue, the conventional route of the city's civic and cultural parades. Measuring six to ten lanes wide with 3-5 meter-wide sidewalks on both sides and a landscaped central median, the boulevard is lined with narra trees. Midway is the park and roundabout of Fuente Osmeña.See also: Vienna Ring Road
The Ring Road (German: Ringstraße) is a circular ring road surrounding the Innere Stadt district of Vienna, Austria and is one of its main sights. Constructed in the mid-19th century after the dismantling of the city fortification walls, its architecture is typical of the eclectic, historicist style called Ringstraßenstil (Ring Road Style) of the 1860s to 1890s.
Known for its unique architectural beauty and history, it has also been called the "Lord of the ring roads", and is inscribed by UNESCO as part of Vienna's World Heritage Site.
The Ringstraße is 5.2 kilometers (3.2 miles) long and has several sections. It surrounds the central area of Vienna on all sides, except for the northeast, where its place is taken by the Franz-Josephs-Kai, the street going along the Donaukanal (a branch of the Danube). Starting from the Ringturm at the northern end of the Franz-Josephs-Kai, the sections are:See also: Boulevards of Paris
Baron Haussmann made such roads well known in his re-shaping of Second Empire Paris between 1853 and 1870. The French word boulevard originally referred to the flat summit of a rampart (the etymology of the word distantly parallels that of bulwark which is a Dutch loanword [bolwerk]). Several Parisian boulevards replaced old city walls; more generally, boulevards encircle a city center, in contrast to avenues that radiate from the center.
Boulevard is sometimes used to describe an elegantly wide road, such as those in Paris, approaching the Champs-Élysées. Famous French boulevards: Avenue Montaigne, Montmartre, Invalides, Boulevard Haussmann. Frequenters of boulevards were sometimes called boulevardiersUnter den Linden, Berlin, Germany.
The historically most famous boulevard in Berlin and arguably in all of Germany is Unter den Linden: location of the Berlin State Opera, Berlin Cathedral, the former royal palace, Humboldt University, the Neue Wache state memorial, the Germany Historical Museum housed in the old arsenal and Brandenburg Gate being the boulevard's focal point. Most famed for its classy shopping facilities is Berlin's Kurfürstendamm.
In the 1920s it was considered one of the most cosmopolitan places in Europe, being not only an elegant residential area but also a major centre of nightlife and leisure. Ku'damm retained this air throughout the Cold War becoming the hub of free West-Berlin. Still today it is the city's most frequented shopping district.
A notable boulevard in Berlin's East is Karl-Marx-Allee, which was built primarily in the 1950s in Stalinist Classicism architecture with decorative buildings. One section of the boulevard is more decorative while the other is more modern. In the center of the boulevard is the Strausberger Platz, which has buildings in wedding-cake style. The boulevard is divided into various blocks. Between 1949 and 1989, it was the main center of East Berlin. The Königsallee in Düsseldorf is known for its many famous fashion stores and showrooms.
Munich is well known for its four royal avenues constructed by the Bavarian monarchs of the 19th century, which can also be classified as boulevards: Brienner Straße, Leopoldstrasse, Maximilianstraße, and Prinzregentenstraße.Combino Supra at the Grand Boulevard, Budapest, Hungary
The Hungarian capital Budapest is also known for its well planned street system with wide avenues and boulevards, running through the city. There are three main boulevards, named Little Boulevard, Grand Boulevard and Hungária Boulevard. Little Boulevard was built on the demolished medieval city walls of Pest in the late 19th century. Grand Boulevard, the most prominent, was built for the 1000th anniversary of the Hungarian conquest in 1896. It has a uniform facade, and the busiest tram line in Europe.
Hungária Boulevard was built from 1980 to 2000 and it is the widest (70 meters, like Champs-Élysées) and longest (13 kilometers) boulevard in Budapest with six to ten traffic lanes and a rapid tram line. Although the construction of the boulevard was finished in 2000, the facade is still incomplete, as there are many empty parcels due to demolition of old apartments and factories.
As in the UK, Ireland also has a lack of boulevards, but O'Connell Street in Dublin is one of Europe's widest streets and is very like a Victorian boulevard. In recent housing developments in Dublin, the boulevard is becoming more and more common in addresses (e.g. Tyrellstown Blvd, Park Blvd, Bayside Blvd), and a boulevard was opened in Gorey, County Wexford in early 2015.Boulevard in Florence, Italy
Florence's historic centre, for example, is surrounded by the Viali di Circonvallazione, a series of 6-lane wide streets; the boulevards follow the outline of the ancient walls of Florence, that were demolished since 1865 to make Florence, then the capital of Italy (for 5 years, 1865–1870), a modern and big city like the other European capitals. The Viali were inspired by the similar Parisian boulevards.Oder in Szczecin
Boulevards are representative places in cities situated near big rivers and usually parts of their centres, for example in Cracow, Warsaw, Toruń, Bydgoszcz, Gdańsk, Gorzów Wielkopolski, Wrocław and Świnoujście.
One of the most famous boulevards in Poland is the street named Wały Chrobrego (former German name: Hakenterrasse) in Szczecin, where the final events of The Tall Ships' Races took place in 2007 and 2013. This is a street complex, about 100 years old, at the river bank of Oder with some connections to the harbour in Szczecin and the Baltic Sea. There are many tourist attractions e.g. National Museum in Szczecin, The Contemporary Theater (Teatr Współczesny), Statue of Hercules fighting the Centaur and the waterfront for ships, including harbour cruise ships and hydrofoil to Świnoujście. In the area there are more historic buildings situated, for instance The Ducal Castle.
Some tourist towns and villages are known among others for their boulevards and esplanades. There are many localities situated by the sea, for example Sopot, Gdynia, Kołobrzeg, Misdroy and Świnoujście, or other types of big water areas as Trzebież lying on the Szczecin Lagoon. Feliks Nowowiejski Seaside Boulevard in Gdynia was the first stage of the Tour de Pologne in 2003. Boulevards are also representative places in Gryfino (dictrict town in Poland) and German village Mescherin localized by both sides of the valley of Oder river protected with Lower Odra Valley Landscape Park.
There are also many boulevards by lakes and small rivers, mainly in harbours areas, as in Giżycko, and in urban parks, for example in Łobez, Piotrków Trybunalski, Poznań and the oldest Polish urban park in Kalisz founded in 1798. Boulevards and paths in Łazienki Park in Warsaw surround Palace on the Water. The medieval port crane, called Żuraw, over Motława river, the junction of two boulevards - Długie Pobrzeże and Rybackie Pobrzeże - is the symbol of the medieval harbour of Gdańsk. The Old Town Promenade (Promenada Staromiejska) in Wrocław was built on the former on the former defensive fortifications along the City Moat and a small section along the Oder river. The boulevard in Kasprowicz Park in Szczecin leads along Rusałka Lake from the City Hall area to The Summer Theater (Teatr Letni) and then to Różanka Rose Garden and the forest of Puszcza Wkrzańska. The scenic above ground promenade in Augustów enables the observation of the Augustów Canal and national roads 8 and 16.Clean Ponds in the wide median green of Chistoprudny Boulevard, Moscow, Russia
The dictionary defines boulevard as a wide green strip in the middle of a city street or on the embankment. Historical Boulevard Ring in Moscow emerged on the site of the former White City walls (demolished in the 1760s and 1770s) before the Fire of 1812, starting with Tverskoy Boulevard in 1796. The whole ring was replanted and rebuilt after the fire, in the 1820s; together with the embankments of Moskva River the boulevards form the second centremost city ring.
Green boulevards of that period were terminated with corner hotel and shop buildings, most of them eventually demolished to make way for street traffic. Garden Ring, developed in the middle of the 19th century, had traditional median boulevards in its western part and side gardens in the east (streets with side strips of green, even those separating main traffic and frontage roads, are not usually considered boulevards).
Street names of Saint Petersburg evolved differently: median greens of major avenues were called boulevards, but the avenues themselves typically were and still are called prospekts (i.e. Bolshoy Prospekt of Vasilievsky Island).
Owing to city planning and physical geography, the UK has only a few boulevards. Glasgow's Mosspark Boulevard, a former segregated tram and car wide road along Bellahouston Park, and Great Western Road, colloqially known as 'The Boulevard' north of the River, is a good example, a mostly dual carriageway road running to the outer suburbs passing through the fashionable West End district, with many shops and bars dotted along the route.
After the Great Fire of London, London was supposed to be formed of straight boulevards, squares and plazas which are seen in mainland Europe, but due to land ownership issues these plans never came to fruition. Boulevards in London are rare but examples, such as Blackfriars Road, do exist. Milton Keynes, Buckinghamshire, is one of only a handful of examples where boulevards are a key feature. This is due to Milton Keynes being built as a modern new town in the 1960s.
Nottingham (and to a lesser extent, Leicester) also have extensive networks of boulevards, although some lower-capacity highways are named boulevards even when they are streets; for example Gilbert Boulevard, Arnold (Asquith Way/Boulevard, West Knighton).
Furthermore, the north-west town of Warrington in Cheshire has a large number of boulevards, some more recent than others. Lining the Gemini Retail Park in Warrington is Europa Boulevard with the traditional tree lined pavements and two-lane traffic. Also, on the recent housing development, Chapelford - built on the old Burtonwood Airbase site, are a number of boulevards such as Boston and Santa Rosa Boulevard, built in reference to the American history associated from World War II on the site.Barbaros Boulevard in Istanbul, Turkey
Barbaros Boulevard is opened in 1958 due to new city planning in Istanbul. Ankara also has a lot of boulevards.View of Mexico City's Paseo de la Reforma from Castillo de Chapultepec.
In the Dominican Republic, more specifically in Greater Santo Domingo there is the Winston Churchill and 27 de Febrero Boulevard in Downtown Santo Domingo and Las Americas Boulevard in Santo Domingo Este. These boulevards are known for their wide median with plazas and trees on it.
Paseo de la Reforma (English: "Reform Promenade") is a 12 kilometer long boulevard in Mexico City, Mexico that runs in a straight line, cutting diagonally across the city. It runs from Chapultepec Park, then passes alongside the Torre Mayor (currently Latin America's tallest building), continues through the fashionable Zona Rosa and then to the Zócalo by Juárez Avenue and Francisco I. Madero Street. One of the most famous monuments of the Paseo is El Ángel de la Independencia – a tall column with a gilded statue of a Winged Victory on its top and marble statues at its base depicting the heroes of the Mexican War of Independence.
The Paseo de la Reforma was designed in the 1860s during the Second Mexican Empire by the Austrian military officer and engineer Ferdinand von Rosenzweig on the orders of Maximilian I of Mexico. He wanted to connect his imperial residence, Chapultepec Castle, to the Palacio Nacional in the city's center. When it was inaugurated, it was named the Paseo de la Emperatriz (The Empress's Promenade), after his consort, Empress Carlota of Mexico. The name now commemorates the liberal reforms of 19th-century president Benito Juárez.Queens Boulevard in New York City Road verge (or Boulevard) in Oak Park, Illinois Roosevelt Boulevard in Philadelphia, Pennsylvania
In many places in the United States of America and Canada, municipalities and developers have adapted the term to refer to arterial roads, not necessarily boulevards in the traditional sense. In California, many so-called "boulevards" extend into the mountains as narrow, winding road segments only two lanes in width. However, boulevards can be any divided highway with at-grade intersections to local streets. They are commonly abbreviated Blvd. Some celebrated examples in California include:
In Chicago, the boulevard system is a network of wide, planted-median boulevards that winds through the south, west, and north sides of the city and includes a ring of parks. Most of the boulevards and parks are 3–6 miles from The Loop. Trucks are not allowed on boulevards in Chicago. Seattle also features a network of boulevards that connect most of the city's public parks to each other, a design recommended by the Olmsted Brothers.
In Philadelphia, the boulevard system includes the length of the Benjamin Franklin Parkway known as the Museum District. It also includes the arterial roadway of the Roosevelt Boulevard and the Southern Boulevard Parkway built as a connecting median of two urban parks, but now also serves as the west roadway entrance of the world class centralized Philadelphia Sports Complex and gatehouse entrance of the Philadelphia Navy Yard in South Philadelphia.
Sometimes, the word "boulevard" is used as a standalone name, as is the case in Atlanta, and Roosevelt Boulevard in the Northeast section of Philadelphia is sometimes referred to, chiefly by locals, simply as "The Boulevard." In Pittsburgh, "The Boulevard of the Allies" runs through and connects major areas of the city.
Kansas City, Missouri and St. Louis, Missouri are famous for having more boulevards and avenues in the world than any city (if the term is used lightly). In Charlotte, North Carolina, Independence Boulevard connects Uptown to the southeastern section of the city, although the westernmost segment is actually a freeway.
New York City has a lot of boulevards, many of which are not designated as such (like Ocean Parkway or Broadway). In the borough of Queens, many important thoroughfares are designated as Boulevards.
Nineteenth century parkways, such as Brooklyn's Ocean Parkway, were often built in the form of boulevards and are informally referred to as such. In some cities, however, the term "boulevard" does not specify a larger, wider, or more important road. "Boulevard" may simply be used as one of many words describing roads in communities containing multiple iterations of the same street name (such as in the Ranchlands district of Calgary, where Ranchlands Boulevard exists side-by-side with Ranchlands Road, Ranchlands Court, Ranchlands Mews, etc.) Nowadays boulevards can be found most anywhere and their original structured meaning has lost almost all meaning.
Lake Shore Boulevard, a six-lane thoroughfare runs along the lakefront in Toronto from Woodbine Avenue in the east to the city limits in the west. The section between Jameson Avenue and the Humber River (the original section), as an example of urban planning, was laid out to provide a pleasant drive with a view of Humber Bay on Lake Ontario and easy access to the park lands by automobile. It was later expanded for commuting.
A famous American example is Las Vegas Boulevard in Las Vegas, Nevada.Norodom Boulevard
Melbourne has at least four roads named "the Boulevard." These are, generally, long roads with many curves which wind alongside the Yarra River. In addition, the spelling of boulevard with an extra 'e' is common, for example the Southlands Boulevarde shopping centre in southern Perth. Australia post officially abbreviates boulevard as "BVD".
Several Melbourne thoroughfares not named as a boulevard do in fact follow the boulevard configuration of multiple lanes and landscaping. These include St Kilda Road, Royal Parade, Victoria Parade, Flemington Road, and the outer section of Mount Alexander Road.
Boulevards in Sydney include:
Additionally, single-suburb boulevards are situated in Brighton-le-Sands, Cammeray, Cheltenham, Epping, Lidcombe, Lilyfield, Malabar, Newport, Sans Souci, Strathfield and Yagoona.
Construction began on the Orewa Boulevard in March 2009, the works are expected to be complete by February 2010. This boulevard will be approximately 400 m long with Pohutukawa and palm lined footpaths, a wide cycleway will be constructed on the beach side of the road and carparks on the business side. The Orewa Boulevard is a project commissioned by the Rodney District Council with the vision of connecting the CBD to Orewa Beach.
Central Christchurch is surrounded and connected by a series of large boulevards (usually called "avenues" in New Zealand). These include four which surround the central city, Bealey Avenue, Fitzgerald Avenue, Deans Avenue, and Moorhouse Avenue, and also Riccarton Avenue, which traverses the large central city park, Hagley Park. The centre of the city is often described locally as being "within the Four Avenues".
Avenida 9 de Julio in the heart of Buenos Aires, which is the capital city of Argentina, is as wide as 7 lanes in each direction, with 4 further lanes flanking the main boulevard in parallel roads on either side.View of Bogota’s La Soledad Park Way Boulevard
In Bogotá, ‘’’La Soledad Park Way Boulevard’’’ is an 1 kilometer important boulevard, in the Locality of Teusaquillo located in Bogotá’s City Center and it crosses from the street 35 to street 45.
In the boulevard you can see several monuments and restaurants including Crepes & Waffles, Kokoriko, Subway, The Cheesecake Factory, and the historical hotel ‘’Hotel Park Way Boulevard’’
In Montevideo, Artigas Boulevard is an important avenue (40 metres (130 ft) wide) that encloses the central area.
Asphalt concrete(Redirected from Asphalt pavement) A road being resurfaced
A road surface or pavement is the durable surface material laid down on an area intended to sustain vehicular or foot traffic, such as a road or walkway. In the past, gravel road surfaces, cobblestone and granite setts were extensively used, but these surfaces have mostly been replaced by asphalt or concrete laid on a compacted base course. Road surfaces are frequently marked to guide traffic. Today, permeable paving methods are beginning to be used for low-impact roadways and walkways. Pavements are crucial to countries such as US and Canada, which heavily depend on road transportation. Therefore, research projects such as Long-Term Pavement Performance are launched to optimize the life-cycle of different road surfaces.Red surfacing for the bicycle lane in the Netherlands Closeup of asphalt on a driveway
Asphalt (specifically, asphalt concrete), sometimes called flexible pavement due to the nature in which it distributes loads, has been widely used since the 1920s. The viscous nature of the bitumen binder allows asphalt concrete to sustain significant plastic deformation, although fatigue from repeated loading over time is the most common failure mechanism. Most asphalt surfaces are laid on a gravel base, which is generally at least as thick as the asphalt layer, although some 'full depth' asphalt surfaces are laid directly on the native subgrade. In areas with very soft or expansive subgrades such as clay or peat, thick gravel bases or stabilization of the subgrade with Portland cement or lime may be required. Polypropylene and polyester geosynthetics have also been used for this purpose and in some northern countries, a layer of polystyrene boards have been used to delay and minimize frost penetration into the subgrade.
Depending on the temperature at which it is applied, asphalt is categorized as hot mix, warm mix, or cold mix. Hot mix asphalt is applied at temperatures over 300 °F (150 °C) with a free floating screed. Warm mix asphalt is applied at temperatures of 200–250 °F (95–120 °C), resulting in reduced energy usage and emissions of volatile organic compounds. Cold mix asphalt is often used on lower-volume rural roads, where hot mix asphalt would cool too much on the long trip from the asphalt plant to the construction site.
An asphalt concrete surface will generally be constructed for high-volume primary highways having an average annual daily traffic load greater than 1200 vehicles per day. Advantages of asphalt roadways include relatively low noise, relatively low cost compared with other paving methods, and perceived ease of repair. Disadvantages include less durability than other paving methods, less tensile strength than concrete, the tendency to become slick and soft in hot weather and a certain amount of hydrocarbon pollution to soil and groundwater or waterways.
In the mid-1960s, rubberized asphalt was used for the first time, mixing crumb rubber from used tires with asphalt. While a potential use for tires that would otherwise fill landfills and present a fire hazard, rubberized asphalt has shown greater incidence of wear in freeze-thaw cycles in temperate zones due to non-homogeneous expansion and contraction with non-rubber components. The application of rubberized asphalt is more temperature-sensitive, and in many locations can only be applied at certain times of the year.
Study results of the long-term acoustic benefits of rubberized asphalt are inconclusive. Initial application of rubberized asphalt may provide 3–5 decibels (dB) reduction in tire-pavement source noise emissions; however, this translates to only 1–3 decibels (dB) in total traffic noise level reduction (due to the other components of traffic noise). Compared to traditional passive attenuating measures (e.g., noise walls and earth berms), rubberized asphalt provides shorter-lasting and lesser acoustic benefits at typically much greater expense.Concrete roadway in San Jose, California Further information: Concrete
Concrete surfaces (specifically, Portland cement concrete) are created using a concrete mix of Portland cement, coarse aggregate, sand and water. In virtually all modern mixes there will also be various admixtures added to increase workability, reduce the required amount of water, mitigate harmful chemical reactions and for other beneficial purposes. In many cases there will also be Portland cement substitutes added, such as fly ash. This can reduce the cost of the concrete and improve its physical properties. The material is applied in a freshly mixed slurry, and worked mechanically to compact the interior and force some of the cement slurry to the surface to produce a smoother, denser surface free from honeycombing. The water allows the mix to combine molecularly in a chemical reaction called hydration.A concrete road in Ewing, New Jersey. The original pavement was laid in the 1950s and has not been significantly altered since.
Concrete surfaces have been refined into three common types: jointed plain (JPCP), jointed reinforced (JRCP) and continuously reinforced (CRCP). The one item that distinguishes each type is the jointing system used to control crack development.
One of the major advantages of concrete pavements is they are typically stronger and more durable than asphalt roadways. They also can be grooved to provide a durable skid-resistant surface. A notable disadvantage is that they typically can have a higher initial cost, and can be more time-consuming to construct. This cost can typically be offset through the long life cycle of the pavement. Concrete pavement can be maintained over time utilizing a series of methods known as concrete pavement restoration which include diamond grinding, dowel bar retrofits, joint and crack sealing, cross-stitching, etc. Diamond grinding is also useful in reducing noise and restoring skid resistance in older concrete pavement.
The first street in the United States to be paved with concrete was Court Avenue in Bellefontaine, Ohio in 1893. The first mile of concrete pavement in the United States was on Woodward Avenue in Detroit, Michigan in 1909. Following these pioneering uses, the Lincoln Highway Association, established in October 1913 to oversee the creation of one of the United States' earliest east-west transcontinental highways for the then-new automobile, began to establish "seedling miles" of specifically concrete-paved roadbed in various places in the American Midwest, starting in 1914 west of Malta, Illinois, while using concrete with the specified concrete "ideal section" for the Lincoln Highway in Lake County, Indiana during 1922 and 1923.An example of composite pavement: hot-mix asphalt overlaid onto Portland cement concrete pavement
Composite pavements combine a Portland cement concrete sublayer with an asphalt. They are usually used to rehabilitate existing roadways rather than in new construction.
Asphalt overlays are sometimes laid over distressed concrete to restore a smooth wearing surface. A disadvantage of this method is that movement in the joints between the underlying concrete slabs, whether from thermal expansion and contraction, or from deflection of the concrete slabs from truck axle loads, usually causes reflective cracks in the asphalt. To decrease reflective cracking, concrete pavement is broken apart through a break and seat, crack and seat, or rubblization process. Geosynthetics can be used for reflective crack control. With break and seat and crack and seat processes, a heavy weight is dropped on the concrete to induce cracking, then a heavy roller is used to seat the resultant pieces into the subbase. The main difference between the two processes is the equipment used to break the concrete pavement and the size of the resulting pieces. The theory is frequent small cracks will spread thermal stress over a wider area than infrequent large joints, reducing the stress on the overlying asphalt pavement. Rubblization is a more complete fracturing of the old, worn-out concrete, effectively converting the old pavement into an aggregate base for a new asphalt road.
Whitetopping uses Portland cement concrete to resurface a distressed asphalt road.An asphalt milling machine in Boise, Idaho.
Distressed road materials can be reused when rehabilitating a roadway. The existing pavement is ground or broken up into small pieces, through a process called milling. It can then be transported to an asphalt or concrete plant and incorporated into new pavement, or recycled in place to form the base or subbase for new pavement. Some methods used include:Main article: Chipseal
Bituminous surface treatment (BST) or chipseal is used mainly on low-traffic roads, but also as a sealing coat to rejuvenate an asphalt concrete pavement. It generally consists of aggregate spread over a sprayed-on asphalt emulsion or cut-back asphalt cement. The aggregate is then embedded into the asphalt by rolling it, typically with a rubber-tired roller. This type of surface is described by a wide variety of regional terms including "chip seal", "tar and chip", "oil and stone", "seal coat", "sprayed seal" or "surface dressing" or as simply "bitumen."
BST is used on hundreds of miles of the Alaska Highway and other similar roadways in Alaska, the Yukon Territory, and northern British Columbia. The ease of application of BST is one reason for its popularity, but another is its flexibility, which is important when roadways are laid down over unstable terrain that thaws and softens in the spring.
Other types of BSTs include micropaving, slurry seals and Novachip. These are laid down using specialized and proprietary equipment. They are most often used in urban areas where the roughness and loose stone associated with chip seals is considered undesirable.
A thin membrane surface (TMS) is an oil-treated aggregate which is laid down upon a gravel road bed, producing a dust-free road. A TMS road reduces mud problems and provides stone-free roads for local residents where loaded truck traffic is negligible. The TMS layer adds no significant structural strength, and so is used on secondary highways with low traffic volume and minimal weight loading. Construction involves minimal subgrade preparation, following by covering with a 50-to-100-millimetre (2.0–3.9 in) cold mix asphalt aggregate. The Operation Division of the Ministry of Highways and Infrastructure in Saskatchewan has the responsibility of maintaining 6,102 kilometres (3,792 mi) of thin membrane surface (TMS) highways.
Otta seal is a low-cost road surface using a 16–30-millimetre (0.63–1.18 in) thick mixture of bitumen and crushed rock.Main article: Gravel road
Gravel is known to have been used extensively in the construction of roads by soldiers of the Roman Empire (see Roman road) but in 1998 a limestone-surfaced road, thought to date back to the Bronze Age, was found at Yarnton in Oxfordshire, Britain. Applying gravel, or "metalling," has had two distinct usages in road surfacing. The term road metal refers to the broken stone or cinders used in the construction or repair of roads or railways, and is derived from the Latin metallum, which means both "mine" and "quarry". The term originally referred to the process of creating a gravel roadway. The route of the roadway would first be dug down several feet and, depending on local conditions, French drains may or may not have been added. Next, large stones were placed and compacted, followed by successive layers of smaller stones, until the road surface was composed of small stones compacted into a hard, durable surface. "Road metal" later became the name of stone chippings mixed with tar to form the road surfacing material tarmac. A road of such material is called a "metalled road" in Britain, a "paved road" in Canada and the US, or a "sealed road" in parts of Canada, Australia and New Zealand.
A granular surface can be used with a traffic volume where the annual average daily traffic is 1,200 vehicles per day or less. There is some structural strength if the road surface combines a sub base and base and is topped with a double graded seal aggregate with emulsion. Besides the 4,929 kilometres (3,063 mi) of granular pavements maintained in Saskatchewan, around 40% of New Zealand roads are unbound granular pavement structures.
The decision whether to pave a gravel road or not often hinges on traffic volume. It has been found that maintenance costs for gravel roads often exceed the maintenance costs for paved or surface-treated roads when traffic volumes exceed 200 vehicles per day.
Some communities are finding it makes sense to convert their low-volume paved roads to aggregate surfaces.
Pavers (or paviours), generally in the form of pre-cast concrete blocks, are often used for aesthetic purposes, or sometimes at port facilities that see long-duration pavement loading. Pavers are rarely used in areas that see high-speed vehicle traffic.
Brick, cobblestone, sett, wood plank, and wood block pavements such as Nicolson pavement, were once common in urban areas throughout the world, but fell out of fashion in most countries, due to the high cost of labor required to lay and maintain them, and are typically only kept for historical or aesthetic reasons. In some countries, however, they are still common in local streets. In the Netherlands, brick paving has made something of a comeback since the adoption of a major nationwide traffic safety program in 1997. From 1998 through 2007, more than 41,000 km of city streets were converted to local access roads with a speed limit of 30 km/h, for the purpose of traffic calming. One popular measure is to use brick paving - the noise and vibration slows motorists down. At the same time, it is not uncommon for cycle paths alongside a road to have a smoother surface than the road itself.
Likewise, macadam and tarmac pavements can still sometimes[when?] be found buried underneath asphalt concrete or Portland cement concrete pavements, but are rarely[clarification needed] constructed today[when?].
There are also other methods and materials to create pavements that have appearance of brick pavements. The first method to create brick texture is to heat an asphalt pavement and use metal wires to imprint a brick pattern using a compactor to create stamped asphalt. A similar method is to use rubber imprinting tools to press over a thin layer of cement to create decorative concrete. Another method is to use a brick pattern stencil and apply a surfacing material over the stencil. Materials that can be applied to give the color of the brick and skid resistance can be in many forms. An example is to use colored polymer-modified concrete slurry which can be applied by screeding or spraying. Another material is aggregate-reinforced thermoplastic which can be heat applied to the top layer of the brick-pattern surface. Other coating materials over stamped asphalt are paints and two-part epoxy coating.
Roadway surfacing choices are known to affect the intensity and spectrum of sound emanating from the tire/surface interaction. Initial applications of noise studies occurred in the early 1970s. Noise phenomena are highly influenced by vehicle speed.
Roadway surface types contribute differential noise effects of up to 4 dB, with chip seal type and grooved roads being the loudest, and concrete surfaces without spacers being the quietest. Asphaltic surfaces perform intermediately relative to concrete and chip seal. Rubberized asphalt has been shown to give a marginal 3–5 dB reduction in tire-pavement noise emissions, and a marginally discernible 1–3 dB reduction in total road noise emissions when compared to conventional asphalt applications.See also: Pothole, Crocodile cracking, Rut (roads), and Bleeding (roads) Deteriorating asphalt
As pavement systems primarily fail due to fatigue (in a manner similar to metals), the damage done to pavement increases with the fourth power of the axle load of the vehicles traveling on it. According to the AASHO Road Test, heavily loaded trucks can do more than 10,000 times the damage done by a normal passenger car. Tax rates for trucks are higher than those for cars in most countries for this reason, though they are not levied in proportion to the damage done. Passenger cars are considered to have little practical effect on a pavement's service life, from a materials fatigue perspective.
Other failure modes include aging and surface abrasion. As years go by, the binder in a bituminous wearing course gets stiffer and less flexible. When it gets "old" enough, the surface will start losing aggregates, and macrotexture depth increases dramatically. If no maintenance action is done quickly on the wearing course, potholes will form. The freeze-thaw cycle in cold climates will dramatically accelerate pavement deterioration, once water can penetrate the surface.
If the road is still structurally sound, a bituminous surface treatment, such as a chipseal or surface dressing can prolong the life of the road at low cost. In areas with cold climate, studded tires may be allowed on passenger cars. In Sweden and Finland, studded passenger car tires account for a very large share of pavement rutting.
The physical properties of a stretch of pavement can be tested using a falling weight deflectometer.
Several design methods have been developed to determine the thickness and composition of road surfaces required to carry predicted traffic loads for a given period of time. Pavement design methods are continuously evolving. Among these are the Shell Pavement design method, and the American Association of State Highway and Transportation Officials (AASHTO) 1993 "Guide for Design of Pavement Structures". A new mechanistic-empirical design guide has been under development by NCHRP (Called Superpave Technology) since 1998. A new design guide called Mechanistic Empirical Pavement Design Guide (MEPDG) was developed and is about to be adopted by AASHTO.
Further research by University College London into pavements has led to the development of an indoor, 80-sq-metre artificial pavement at a research centre called Pedestrian Accessibility and Movement Environment Laboratory (PAMELA). It is used to simulate everyday scenarios, from different pavement users to varying pavement conditions. There also exists a research facility near Auburn University, the NCAT Pavement Test Track, that is used to test experimental asphalt pavements for durability.
In addition to repair costs, the condition of a road surface has economic effects for road users. Rolling resistance increases on rough pavement, as does wear and tear of vehicle components. It has been estimated that poor road surfaces cost the average US driver $324 per year in vehicle repairs, or a total of $67 billion. Also, it has been estimated that small improvements in road surface conditions can decrease fuel consumption between 1.8 and 4.7%.Main article: Road surface marking
Road surface markings are used on paved roadways to provide guidance and information to drivers and pedestrians. It can be in the form of mechanical markers such as cat's eyes, botts' dots and rumble strips, or non-mechanical markers such as paints, thermoplastic, plastic and epoxy.