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Present Serviceability Index
The present serviceability index (PSI) is a pavement performance measure. Introduced by the American Association of State Highway and Transportation Officials (AASHTO), the PSI is one of the most widely used pavement performance indicators after pavement condition index (PCI) and international roughness index (IRI). This performance indicator ranges between 0 and 5, 0 representing a failed pavement and 5 an excellent one. Since the PSI entails slope variance, it is correlated with performance indicators related to roughness such as IRI. History The PSI was developed based on the AASHO Road Test's present serviceability rating (PSR). AASHO Road Test was a set of experiments carried out by the AASHTO from 1956 to 1961. Unlike the PSR, which was a ride quality rating that required a panel of observers to ride in a car over the pavement of interest, the PSI does not require a panel of experts. Therefore, it was a more practical approach for large-scale pavement networks. Calcu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Association Of State Highway And Transportation Officials
The American Association of State Highway and Transportation Officials (AASHTO) is a standards setting body which publishes specifications, test quality control, protocols, and guidelines that are used in highway design and construction throughout the United States. Despite its name, the association represents not only highways but air, rail, water, and public transportation as well. Although AASHTO sets transportation standards and policy for the United States as a whole, AASHTO is not an agency of the federal government; rather it is an organization of the states themselves. Policies of AASHTO are not federal laws or policies, but rather are ways to coordinate state laws and policies in the field of transportation. Purpose The American Association of State Highway Officials (AASHO) was founded on December 12, 1914. Its name was changed to American Association of State Highway and Transportation Officials on November 13, 1973. The name change reflects a broadened scope to co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pavement Performance Modeling
Pavement performance modeling or pavement deterioration modeling is the study of pavement deterioration throughout its life-cycle. The health of pavement is assessed using different performance indicators. Some of the most well-known performance indicators are Pavement Condition Index (PCI), International Roughness Index (IRI) and ''Present Serviceability Index'' (PSI), but sometimes a single distress such as rutting or the extent of crack is used. Among the most frequently used methods for pavement performance modeling are mechanistic models, mechanistic-empirical models, survival curves and Markov models. Recently, machine learning algorithms have been used for this purpose as well. Most studies on pavement performance modeling are based on IRI. History The study of pavement performance goes back to the first half of 20th century. The first efforts in pavement performance modeling were based on mechanistic models. Later researchers also developed empirical models, which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AASHO Road Test
The AASHO Road Test was a series of experiments carried out by the American Association of State Highway and Transportation Officials (AASHTO), to determine how traffic contributed to the deterioration of highway pavements. Methodology Officially, the Road Test was "...to study the performance of pavement structures of known thickness under moving loads of known magnitude and frequency." This study, carried out in the late 1950s in Ottawa, Illinois, is frequently quoted as a primary source of experimental data when vehicle wear to highways is considered, for the purposes of road design, vehicle taxation and costing. The road test consisted of six two-lane loops along the future alignment of Interstate 80. Each lane was subjected to repeated loading by a specific vehicle type and weight. The pavement structure within each loop was varied so that the interaction of vehicle loads and pavement structure could be investigated. Satellite studies were planned in other parts of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Present Serviceability Rating
The present (or here'' and ''now) is the time that is associated with the events perceived directly and in the first time, not as a recollection (perceived more than once) or a speculation (predicted, hypothesis, uncertain). It is a period of time between the past and the future, and can vary in meaning from being an instant to a day or longer. It is sometimes represented as a hyperplane in space-time, typically called "now", although modern physics demonstrates that such a hyperplane cannot be defined uniquely for observers in relative motion. The present may also be viewed as a duration (see ''specious present'').James, W. (1893)The principles of psychology New York: H. Holt and Company. Page 609. Historiography Contemporary history describes the historical timeframe immediately relevant to the present time and is a certain perspective of modern history. Philosophy and religion Philosophy of time "The present" raises the question: "How is it that all sentient beings ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flexible Pavement
Highway engineering is an engineering discipline branching from civil engineering that involves the planning, design, construction, operation, and maintenance of roads, bridges, and tunnels to ensure safe and effective transportation of people and goods."Highway engineering." McGraw-Hill Concise Encyclopedia of Science and Technology. New York: McGraw-Hill, 2006. Credo Reference. Web. 13 February 2013. Highway engineering became prominent towards the latter half of the 20th century after World War II. Standards of highway engineering are continuously being improved. Highway engineers must take into account future traffic flows, design of highway intersections/interchanges, geometric alignment and design, highway pavement materials and design, structural design of pavement thickness, and pavement maintenance. History The beginning of road construction could be dated to the time of the Romans. With the advancement of technology from carriages pulled by two horses to vehicles with pow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rut (roads)
A rut is a depression or groove worn into a road or path by the travel of wheels or skis. Ruts can be formed by wear, as from studded snow tires common in cold climate areas, or they can form through the deformation of the asphalt concrete, pavement or subbase material. In modern roads the main cause is heavily loaded trucks. These heavy loaded trucks imprint their tire impressions on roads over time, causing ruts. Rut is a common pavement distress and is often used in pavement performance modeling. Ruts prevent rainwater from flowing to the side of the road into ditches or gutters. Rainwater trapped in ruts is a common contributing factor to hydroplaning crashes. Severe ruts can impede steering if a vehicle has difficulty steering out of the rut. If it proves impossible to steer out of a rut, though forward and backward progress can be made by the vehicle, it is referred to as being stuck in the rut. Ruts in gravel roads can be removed by grading the road surface. Ruts in asph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pavement Cracking
Pavement crack refers to a variety of types of pavement distresses that occur on the surface of pavements. Different types of pavements develop different cracks. Type of cracking is also correlated with the type of climate and traffic. Sometimes the cracks are aggregated using an index such as Crack index, and sometimes they are merged with other distresses and are reported using Pavement Condition Index. Types of cracking Some of the most important types of crack are as follows: * Crocodile cracking, also known as alligator cracking and fatigue cracking * Block cracking (caused by shrinkage of asphalt) * Longitudinal cracking—wheel path * Longitudinal cracking—non-wheel path * Transverse cracking * Reflection cracking at joints * Edge cracking (caused because of poor drainage or lack of support at the edge) * Slippage cracking References {{Road types Pavement distress Pavements Pavement engineering ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pavements
Pavement may refer to: * Pavement (architecture), an outdoor floor or superficial surface covering * Road surface, the durable surfacing of roads and walkways ** Asphalt concrete, a common form of road surface * Sidewalk or pavement, a walkway along the side of a road * Cool pavement, is pavement that delivers higher solar reflectance than conventional dark pavement. * Pavement (York), a street in York, in England Geology * Limestone pavement, a naturally occurring landform that resembles an artificial pavement * Desert pavement, a desert ground surface covered with closely packed rock fragments of pebble and cobble size * Tessellated pavement, a rare sedimentary rock formation that occurs on some ocean shores * Glacial striation or glacial pavement, a rock surface scoured and polished by glacial action Arts and entertainment * Pavement (band), an indie rock band from Stockton, California, US * ''Pavement'' (magazine), a youth culture magazine * "Pavement" (''Space Ghost Coast ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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