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Drainage Gradient
Drainage gradient (DG) is a term in road design, defined as the combined slope due to road surface cross slope (CS) and longitudinal slope (hilliness). Although the term may not be used, the concept is also used in roof design and landscape architecture. If the drainage gradient is too low, rain and melt water drainage will be insufficient. This results in water pooling on the road surface, thereby increasing the risk for hydroplaning Aquaplaning or hydroplaning by the tires of a road vehicle, aircraft or other wheeled vehicle occurs when a layer of water builds between the wheels of the vehicle and the road surface, leading to a loss of traction (engineering), traction tha ... and wet-pavement vehicle crashes. Minimum drainage gradient Most road design manuals require drainage gradient to exceed 0.5%, in order to drain water and prevent excessive skid accidents. One exception to the minimum 0.5% DG limit can be found in the Norwegian road design manual, where the min ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
200907201000 Vattenplaningsrisk
9 (nine) is the natural number following and preceding . Evolution of the Hindu–Arabic digit Circa 300 BC, as part of the Brahmi numerals, various Indians wrote a digit 9 similar in shape to the modern closing question mark without the bottom dot. The Kshatrapa, Andhra and Gupta started curving the bottom vertical line coming up with a -look-alike. How the numbers got to their Gupta form is open to considerable debate. The Nagari continued the bottom stroke to make a circle and enclose the 3-look-alike, in much the same way that the sign @ encircles a lowercase ''a''. As time went on, the enclosing circle became bigger and its line continued beyond the circle downwards, as the 3-look-alike became smaller. Soon, all that was left of the 3-look-alike was a squiggle. The Arabs simply connected that squiggle to the downward stroke at the middle and subsequent European change was purely cosmetic. While the shape of the glyph for the digit 9 has an ascender in most modern typefa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Road
A road is a thoroughfare used primarily for movement of traffic. Roads differ from streets, whose primary use is local access. They also differ from stroads, which combine the features of streets and roads. Most modern roads are paved. The words "road" and "street" are commonly considered to be interchangeable, but the distinction is important in urban design. There are many types of roads, including parkways, avenues, controlled-access highways (freeways, motorways, and expressways), tollways, interstates, highways, and local roads. The primary features of roads include lanes, sidewalks (pavement), roadways (carriageways), medians, shoulders, verges, bike paths (cycle paths), and shared-use paths. Definitions Historically, many roads were simply recognizable routes without any formal construction or some maintenance. The Organization for Economic Co-operation and Development (OECD) defines a road as "a line of communication (travelled way) using a stab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cross Slope
Cross slope, cross fall or camber is a geometric feature of pavement surfaces: the transverse slope with respect to the horizon. It is a very important safety factor. Cross slope is provided to provide a drainage gradient so that water will run off the surface to a drainage system such as a street gutter or ditch. Inadequate cross slope will contribute to aquaplaning. On straight sections of normal two-lane roads, the pavement cross section is usually highest in the center and drains to both sides. In horizontal curves, the cross slope is banked into superelevation to reduce steering effort and lateral force required to go around the curve. All water drains to the inside of the curve. If the cross slope magnitude oscillates within , the body and payload of high (heavy) vehicles will experience high roll and lateral vibration. Cross slope is usually expressed as a percentage: :\text = \frac \times 100\%. Cross slope is the angle around a vertical axis between: * the horizontal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grade (slope)
The grade (US) or gradient (UK) (also called stepth, slope, incline, mainfall, pitch or rise) of a physical feature, landform or constructed line is either the elevation angle of that surface to the horizontal plane, horizontal or its tangent. It is a special case of the slope, where zero indicates horizontal plane, horizontality. A larger number indicates higher or steeper degree of "tilt". Often slope is calculated as a ratio of "rise" to "run", or as a fraction ("rise over run") in which ''run'' is the horizontal distance (not the distance along the slope) and ''rise'' is the vertical distance. Slopes of existing physical features such as canyons and hillsides, bank (geography), stream and river banks, and stream bed, beds are often described as grades, but typically the word "grade" is used for human-made surfaces such as roads, landscape grading, roof pitches, rail tracks, railroads, aqueduct (watercourse), aqueducts, and pedestrian or bicycle routes. The grade may refer to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roof
A roof (: roofs or rooves) is the top covering of a building, including all materials and constructions necessary to support it on the walls of the building or on uprights, providing protection against rain, snow, sunlight, extremes of temperature, and wind. A roof is part of the building envelope. The characteristics of a roof are dependent upon the purpose of the building that it covers, the available roofing materials and the local traditions of construction and wider concepts of architectural design and practice, and may also be governed by local or national legislation. In most countries, a roof protects primarily against rain. A verandah may be roofed with material that protects against sunlight but admits the other elements. The roof of a Conservatory (greenhouse), garden conservatory protects plants from cold, wind, and rain, but admits light. A roof may also provide additional living space, for example, a roof garden. Etymology Old English 'roof, ceiling, top, summ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Landscape Architecture
Landscape architecture is the design of outdoor areas, landmarks, and structures to achieve environmental, social-behavioural, or aesthetic outcomes. It involves the systematic design and general engineering of various structures for construction and human use, investigation of existing social, ecological, and soil conditions and processes in the landscape, and the design of other interventions that will produce desired outcomes. The scope of the profession is broad and can be subdivided into several sub-categories including professional or licensed landscape architects who are regulated by governmental agencies and possess the expertise to design a wide range of structures and landforms for human use; landscape design which is not a licensed profession; site planning; stormwater management; erosion control; environmental restoration; public realm, parks, recreation and urban planning; visual resource management; green infrastructure planning and provision; and private estate and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroplaning (tires)
Aquaplaning or hydroplaning by the tires of a road vehicle, aircraft or other wheeled vehicle occurs when a layer of water builds between the wheels of the vehicle and the road surface, leading to a loss of traction that prevents the vehicle from responding to control inputs. If it occurs to all wheels simultaneously, the vehicle becomes, in effect, an uncontrolled sled. Aquaplaning is a different phenomenon from when water on the surface of the roadway merely acts as a lubricant. Traction is diminished on wet pavement even when aquaplaning is not occurring. Causes Every vehicle function that changes direction or speed relies on friction between the tires and the road surface. The grooves of a rubber tire are designed to disperse water from beneath the tire, providing high friction even in wet conditions. Aquaplaning occurs when a tire encounters more water than it can dissipate. Water pressure in front of the wheel forces a wedge of water under the leading edge of the tire, c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cant (road/rail)
The cant of a Rail transport, railway track or camber angle, camber of a road (also referred to as superelevation, cross slope or cross fall) is the rate of change in elevation (height) between the two rails or edges of the road. This is normally greater where the railway or road is curved; raising the outer rail or the outer edge of the road creates a banked turn, thus allowing vehicles to travel round the curve at greater speeds than would be possible if the surface were level. Rail Superelevation in railway tracks ;Importance of superelevation In curved railway tracks, the outer rail is elevated, providing a banked turn. This allows trains to navigate curves at higher speeds and reduces the pressure of the wheel flanges against the rails, minimizing friction and wear. The difference in elevation between the outer and inner rails is referred to as cant in most countries. ;How superelevation works The main functions of cant are the following: * Improve distribution of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skid (automobile)
An automobile skid is an automobile handling condition where one or more tires are slipping relative to the road, and the overall handling of the vehicle has been affected. Subtypes of skid include: * fishtailing, where the vehicle yaws back and forth across the direction of motion. * ''spin'' or ''spinout'' where a vehicle rotates in one direction during the skid. * understeer and oversteer where front or rear wheels lose traction during cornering, causing a vehicle to follow a larger or smaller turning radius. * ''burnout'' where a vehicle slips or spins its tires during acceleration. * ''lockup'' where a vehicle skids during braking (with or without directional or yaw changes). __TOC__ Slip and skid Tire slip, and related slip angle (angle of motion relative to tire), describe the performance of an individual tire. Important concepts about slip and skid include circle of forces or circle of traction, and cornering force. To a first approximation, the tire can withstand a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asphalt Pavement
A road surface (British English) or pavement (North American English) 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, macadam, hoggin, cobblestone and granite setts were extensively used, but these have mostly been replaced by asphalt or concrete laid on a compacted base course. Asphalt mixtures have been used in pavement construction since the beginning of the 20th century and are of two types: metalled (hard-surfaced) and unmetalled roads. Metalled roadways are made to sustain vehicular load and so are usually made on frequently used roads. Unmetalled roads, also known as gravel roads or dirt roads, are rough and can sustain less weight. Road surfaces are frequently marked to guide traffic. Today, permeable paving methods are beginning to be used for low-impact roadways and walkways to prevent flooding. Pavements are crucial to countries such as United States an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diamond Grinding Of Pavement
Diamond grinding is a pavement preservation technique that corrects a variety of surface imperfections on both concrete and asphalt concrete pavements. Most often utilized on concrete pavement, diamond grinding is typically performed in conjunction with other concrete pavement preservation (CPP) techniques such as road slab stabilization, full- and partial-depth repair, dowel bar retrofit, cross stitching longitudinal cracks or joints and joint and crack resealing. Diamond grinding restores rideability by removing surface irregularities caused during construction or through repeated traffic loading over time. The immediate effect of diamond grinding is a significant improvement in the smoothness of a pavement. Another important effect of diamond grinding is the considerable increase in surface macrotexture and consequent improvement in skid resistance, noise reduction and safety. History The industry can be traced back to an event where a single diamond blade mounted on a concret ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
