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Road Junction
A junction is where two or more roads meet. History Roads are a means of transport, historically linking locations such as towns, forts and geographic features such as river fords. Where roads met outside of an existing settlement, these junctions often led to a new settlement. Scotch Corner is an example of such a location. In the United Kingdom and other countries, the practice of giving names to junctions emerged, to help travellers find their way. Junctions often took the name of a prominent nearby business or a point of interest. As road networks and traffic flows increased in density, managing the flow of traffic through junctions became of increasing importance, to minimize delays and improve safety. The first innovation was to add traffic control devices, such as stop signs and traffic lights that regulated traffic flow. Next came lane controls that limited what each lane of traffic was allowed to do while crossing. Turns across oncoming traffic might be prohibited, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diverging Diamond Interchange
A diverging diamond interchange (DDI), also called a double crossover diamond interchange (DCD), is a subset of diamond interchange in which the opposing directions of travel on the non-freeway road cross each other on either side of the interchange so that traffic crossing the freeway on the overpass or underpass is operating on the opposite driving side from that which is customary for the jurisdiction. The crossovers may employ one-side overpasses or be at-grade and controlled by traffic lights. The diverging diamond interchange has advantages in both efficiency and safety, and was cited by ''Popular Science'' as one of the best engineering innovations of 2009 and in the U.S. has been promoted as part of the Federal Highway Administration's Every Day Counts initiative. The flow through a diverging diamond interchange using overpasses at the crossovers is limited only by Grade separation#Weaving, weaving, and the flow through an implementation using traffic lights is subject ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roundabout Interchange
A roundabout interchange is a type of interchange (road), interchange between a controlled access highway, such as a motorway or freeway, and a minor road. The slip roads to and from the motorway carriageways converge at a single roundabout, which is grade separation, grade-separated from the motorway lanes with bridges. Design A roundabout interchange is similar to a rotary (interchange), rotary interchange, which uses a rotary rather than a roundabout. Roundabouts may also be used in conjunction with other interchange types such as a standard or folded diamond interchange, but such use should not be confused with a roundabout interchange. Roundabout interchanges are extremely common in the United Kingdom and Ireland with hundreds on the motorway network alone. However, recent cost reduction, cost cutting has meant that dumbbell interchanges are increasingly used instead. These are essentially diamond interchanges with roundabouts instead of signals or stop signs where the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roundabout
A roundabout, a rotary and a traffic circle are types of circular intersection or junction in which road traffic is permitted to flow in one direction around a central island, and priority is typically given to traffic already in the junction.''The New Shorter Oxford English Dictionary,'' Volume 2, Clarendon Press, Oxford (1993), page 2632 In the United States, engineers use the term modern roundabout to refer to junctions installed after 1960 that incorporate design rules to increase safety. Compared to stop signs, traffic signals, and earlier forms of roundabouts, modern roundabouts reduce the likelihood and severity of collisions greatly by reducing traffic speeds through horizontal deflection and minimising T-bone and head-on collisions. Variations on the basic concept include integration with tram or train lines, two-way flow, higher speeds and many others. For pedestrians, traffic exiting the roundabout comes from one direction, instead of three, simplifying the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dumbbell Interchange
The dumbbell, a type of free weight, is a piece of equipment used in weight training. It is usually used individually and/or in pairs, with one in each hand. History The forerunner of the dumbbell, halteres, were used in ancient Greece as lifting weights and also as weights for the ancient Greek version of the long jump. A kind of dumbbell was also used in India for more than a millennium, shaped like a club – so it was named Indian club. The design of the "Meel", as the club was referred to, can be seen as a halfway point between a barbell and a dumbbell. It was generally used in pairs, in workouts by wrestlers, bodybuilders, sports players, and others wishing to increase strength and muscle size. Etymology The term "dumbbell" or "dumb bell" or "dumb-bell" originated in late Stuart England. In 1711 the poet Joseph Addison mentioned exercising with a "dumb bell" in an essay published in ''The Spectator''. Although Addison elsewhere in the same publication describes havin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roundabout
A roundabout, a rotary and a traffic circle are types of circular intersection or junction in which road traffic is permitted to flow in one direction around a central island, and priority is typically given to traffic already in the junction.''The New Shorter Oxford English Dictionary,'' Volume 2, Clarendon Press, Oxford (1993), page 2632 In the United States, engineers use the term modern roundabout to refer to junctions installed after 1960 that incorporate design rules to increase safety. Compared to stop signs, traffic signals, and earlier forms of roundabouts, modern roundabouts reduce the likelihood and severity of collisions greatly by reducing traffic speeds through horizontal deflection and minimising T-bone and head-on collisions. Variations on the basic concept include integration with tram or train lines, two-way flow, higher speeds and many others. For pedestrians, traffic exiting the roundabout comes from one direction, instead of three, simplifying the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Federal Highway Administration
The Federal Highway Administration (FHWA) is a division of the United States Department of Transportation that specializes in highway transportation. The agency's major activities are grouped into two programs, the Federal-aid Highway Program and the Federal Lands Highway Program. Its role had previously been performed by the Office of Road Inquiry, Office of Public Roads and the Bureau of Public Roads. History Background With the coming of the bicycle in the 1890s, interest grew regarding the improvement of streets and roads in America. The traditional method of putting the burden on maintaining roads on local landowners was increasingly inadequate. In 1893, the federal Office of Road Inquiry (ORI) was founded; in 1905, it was renamed the Office of Public Roads (OPR) and made a division of the United States Department of Agriculture. Demands grew for local and state government to take charge. With the coming of the automobile, urgent efforts were made to upgrade and moderniz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Double Crossover Merging Interchange
A diverging diamond interchange (DDI), also called a double crossover diamond interchange (DCD), is a subset of diamond interchange in which the opposing directions of travel on the non-freeway road cross each other on either side of the interchange so that traffic crossing the freeway on the overpass or underpass is operating on the opposite driving side from that which is customary for the jurisdiction. The crossovers may employ one-side overpasses or be at-grade and controlled by traffic lights. The diverging diamond interchange has advantages in both efficiency and safety, and was cited by ''Popular Science'' as one of the best engineering innovations of 2009 and in the U.S. has been promoted as part of the Federal Highway Administration's Every Day Counts initiative. The flow through a diverging diamond interchange using overpasses at the crossovers is limited only by weaving, and the flow through an implementation using traffic lights is subject to only two clearance i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stack Interchange
A directional interchange, colloquially known as a stack interchange, is a type of grade-separated junction between two controlled-access highways that allows for free-flowing movement to and from all directions of traffic. These interchanges eliminate the problems of weaving, have the highest vehicle capacity, and vehicles travel shorter distances when compared to different types of interchanges. The first directional interchange built in the world was the Four Level Interchange which opened to Los Angeles traffic in 1949. Definition A directional interchange is a grade separated junction between two roads where all turns that require crossing over or under the opposite road's lanes of travel to complete the turn utilize ramps that make a direct or semi-direct connection. The difference between direct and semi-direct connections is how much the motorist deviates from the intended direction of travel while on the ramp. Direct ramps are shorter and can handle higher traveling ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cloverleaf Interchange
A cloverleaf interchange is a two-level interchange (road), interchange in which all turns are handled by slip roads. To go left (in right-hand traffic; reverse directions in left-driving regions), vehicles first continue as one road passes over or under the other, then exit right onto a one-way three-quarter loop ramp (270°) and merge onto the intersecting road. The objective of a cloverleaf is to allow two highways to cross without the need for any traffic to be stopped by traffic lights. The limiting factor in the capacity of a cloverleaf interchange is traffic weaving. Overview Cloverleaf interchanges, viewed from overhead or on maps, resemble the leaf, leaves of a four-leaf clover or less often a 3-leaf clover. In the United States, cloverleaf interchanges existed long before the Interstate highway, Interstate system. They were originally created for busier interchanges that the original diamond interchange system could not handle. Their chief advantage was that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Free-flow Interchange
A free-flow interchange is an interchange in which all roads are grade-separated, and where movement from one road to another does not require the driver to stop for traffic (for example, the interchange may not include traffic lights or unsignalized at-grade intersections). Free-flow interchanges are less likely to induce traffic congestion than non-free-flow, but are typically more expensive both in money and in land. Some free-flow interchanges bring additional problems such as weaving or passing lane/fast lane exits (i.e. left exits in areas with right-hand traffic, and vice versa) that may be necessary to avoid additional costs, but lead to congestion and accidents and ultimately to an upgrade to another type of interchange. A free flow interchange design called double crossover merging interchange (DCMI) has received a patent."United States Patent 8,950,970: Double Crossover Merging Interchange". United States Patent and Trademark Office. February 10, 2015. Retrieved Au ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Partial Cloverleaf Interchange
A partial cloverleaf interchange or parclo is a modification of a cloverleaf interchange. The design has been well received, and has since become one of the most popular freeway-to-arterial interchange designs in North America. It has also been used occasionally in some European countries, such as Germany, Hungary, Italy, the Netherlands, and the United Kingdom. Comparison with other interchanges *A diamond interchange has four ramps. *A cloverleaf interchange has eight ramps, as does a stack interchange. They are fully grade separated, unlike a parclo, and have traffic flow without stops on all ramps and throughways. *A parclo generally has either four or six ramps but less commonly has five or seven ramps. Naming In Ontario, the specific variation is identified by a letter/number suffix after the name. Ontario's naming conventions are used in this article. The letter ''A'' designates that two ramps meet the freeway ''ahead'' of the arterial road, while ''B'' designates th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
