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Interstate Highway Standards
Standards for Interstate Highways in the United States are defined by the American Association of State Highway and Transportation Officials (AASHTO) in the publication ''A Policy on Design Standards: Interstate System''. For a certain highway to be considered an Interstate Highway, it must meet these construction requirements or obtain a waiver from the Federal Highway Administration. Standards Standardization helps keep road design consistent, such that drivers can learn the consistent features and drive accordingly. Standardization can therefore decrease accidents and increase driver safety. These standards are, : * Controlled access: All access onto and off the highway is to be controlled access, controlled with Interchange (road), interchanges and grade separations, including all railroad crossings. Interchanges are to provide access to and from both directions of the highway and both directions of the crossroad. Interchanges should be spaced at least apart in urban ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States
The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 contiguous states border Canada to the north and Mexico to the south, with the semi-exclave of Alaska in the northwest and the archipelago of Hawaii in the Pacific Ocean. The United States asserts sovereignty over five Territories of the United States, major island territories and United States Minor Outlying Islands, various uninhabited islands in Oceania and the Caribbean. It is a megadiverse country, with the world's List of countries and dependencies by area, third-largest land area and List of countries and dependencies by population, third-largest population, exceeding 340 million. Its three Metropolitan statistical areas by population, largest metropolitan areas are New York metropolitan area, New York, Greater Los Angeles, Los Angel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Driveways
A driveway (also called ''drive'' in UK English) is a private road for local access to one or a small group of structures owned and maintained by an individual or group. Driveways rarely have traffic lights, but some may if they handle heavy traffic, especially those leading to commercial businesses or parks. Driveways may be designed and decorated 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, cleared of snow, or maintained by governments. They are generally designed to conform to the architecture, standards, and landscaping of connected houses or other buildings. Some materials used for driveways include concrete, decorative brick, cobblestone, block paving, asphalt, gravel, resin-bound paving, and decomposed granite. These materials may be surrounded with grass or other ground-cover plants. Driveways are commonly used as paths to private garages, carports, ... [...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] |
Directional Design Hour Volume
Direction may refer to: *Body relative direction, for instance left, right, forward, backwards, up, and down ** Anatomical terms of location for those used in anatomy ** List of ship directions *Cardinal direction *Bearing (navigation) Mathematics and science * Direction vector, a unit vector that defines a direction in multidimensional space * Direction of a subspace of a Euclidean or affine space * Directed set, in order theory * Directed graph, in graph theory * Directionality (molecular biology), the orientation of a nucleic acid Music * For the guidance and cueing of a group of musicians during performance, see conducting * ''Direction'' (album) a 2007 album by The Starting Line * Direction Records, a label began by Bobby Darin. * Direction (record label), a record label in the UK in the late 1960s, a subsidiary of CBS Records, specialising in soul music * '' Directions: The Plans Video Album'', a DVD video album made of videos inspired by songs from indie rock/pop ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shoulder (highway)
A shoulder (American English), hard shoulder (British English) or breakdown lane (Australian English) is an emergency stopping lane by the verge on the outer side of a road or motorway. Many wider freeways, or expressways elsewhere have shoulders on both sides of each directional carriageway—in the median, as well as at the outer edges of the road, for additional safety. Shoulders are not intended for use by through traffic, although there are exceptions. Purpose Shoulders have multiple uses, including: * Emergency vehicles such as ambulances, fire trucks and police cars may use the shoulder to bypass traffic congestion in some countries. * In the event of an emergency or breakdown, a motorist can pull into the shoulder to get out of the flow of traffic and obtain a greater degree of safety. * Active traffic management, used on busy multi-lane roads, may allow 'hard shoulder running' by general traffic at reduced speeds during periods of high traffic volumes. * In some pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Runaway Truck Ramp
A runaway truck ramp, runaway truck lane, escape lane, safety ramp, emergency escape ramp, or truck arrester bed is a traffic device that enables vehicles which are having braking problems to stop safely. It is typically a long, sand- or gravel-filled lane connected to a steep downhill Grade (slope), grade section of a main road, and is designed to accommodate large trucks or buses. It allows a moving vehicle's kinetic energy to be dissipated gradually in a controlled and relatively harmless way, helping the operator stop it safely. Design Emergency escape ramps are usually located in mountainous areas which cause high construction costs and present difficult site selection. Designs include: *''Arrester bed'': a gravel-filled ramp adjacent to the road that uses rolling resistance to stop the vehicle. The required length of the bed depends on the mass and speed of the vehicle, the grade of the arrester bed, and the rolling resistance provided by the gravel. These are similar to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Climbing Lane
A climbing lane, crawler lane (UK), or truck lane, is an additional roadway lane that allows heavy or underpowered vehicles to ascend a steep Grade (slope), grade without slowing other traffic. They are typically used by large trucks or semi-trailer trucks, which go uphill more slowly than they travel on level ground. They are often used on major routes such as motorways and interstate highways. A more modern variation is to keep an existing lane for slow traffic and make the additional lane a passing lane. This keeps slow traffic in the slowest lane even if drivers neglect to change lanes, while allowing drivers who wish to pass the choice of changing lanes to do so. Downhill lanes Some climbing lanes extend slightly over the crest of the hill, to allow slow vehicles to regain speed. As trucks and recreational vehicles must use Gear train, low gear to descend slowly, an additional lane may also be built on the downhill side. This prevents the vehicles from overusing their brak ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Level Of Service (transportation)
Level of service (LOS) is a qualitative measure used to relate the quality of motor vehicle traffic service. LOS is used to analyze roadways and intersections by categorizing traffic flow and assigning quality levels of traffic based on performance measure like vehicle speed, density, congestion, etc. In a more general sense, levels of service can apply to all services in asset management domain. Level-of-Service in the United States of America The following section pertains to only North American highway LOS standards as in the Highway Capacity Manual (HCM) and AASHTO Geometric Design of Highways and Streets ("Green Book"), using letters A through F, with A being the best and F being the worst, similar to academic grading. A: free flow. Traffic flows at or above the posted speed limit and motorists have complete mobility between lanes. The average spacing between vehicles is about 550 ft(167m) or 27 car lengths. Motorists have a high level of physical and psychological com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lane
In road transport, a lane is part of a roadway that is designated to be used by a single line of vehicles to control and guide drivers and reduce traffic conflicts. Most public roads (highways) have at least two lanes, one for traffic in each direction, separated by lane markings. On multilane roadways and busier two-lane roads, lanes are designated with road surface markings. Major highways often have two multi-lane roadways separated by a median. Some roads and bridges that carry very low volumes of traffic are less than wide, and are only a single lane wide. Vehicles travelling in opposite directions must slow or stop to pass each other. In rural areas, these are often called country lanes. In urban areas, alleys are often only one lane wide. Urban and suburban one lane roads are often designated for one-way traffic. History For much of human history, roads did not need lane markings because most people walked or rode horses at relatively slow speeds. However, when ... [...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] |
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] |
Curvature
In mathematics, curvature is any of several strongly related concepts in geometry that intuitively measure the amount by which a curve deviates from being a straight line or by which a surface deviates from being a plane. If a curve or surface is contained in a larger space, curvature can be defined ''extrinsically'' relative to the ambient space. Curvature of Riemannian manifolds of dimension at least two can be defined ''intrinsically'' without reference to a larger space. For curves, the canonical example is that of a circle, which has a curvature equal to the reciprocal of its radius. Smaller circles bend more sharply, and hence have higher curvature. The curvature ''at a point'' of a differentiable curve is the curvature of its osculating circle — that is, the circle that best approximates the curve near this point. The curvature of a straight line is zero. In contrast to the tangent, which is a vector quantity, the curvature at a point is typically a scalar q ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
