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Bi-directional Vehicle
A bi-directional vehicle is a vehicle that can be driven in either direction, forwards or backwards. Usually, the term refers to rail vehicles, such as trains or trams, and some airside transfer buses, that are equipped with driver's cabs at both ends. These vehicles generally have entry and exit doors on either side of the vehicle. One major benefit of bi-directional vehicles is the ability to reverse direction at a terminal station with a stub-end track. On a system using double track, a crossover switch is often used to move the vehicle to the other track. This situation contrasts with the use of uni-directional vehicles, which requires the use of a balloon loop, triangle junction, or turntable to reverse direction. Aside from eliminating the need for complicated railway infrastructure to turn vehicles around, the presence of doors on either side of the vehicle enable the use of island platform An island platform (also center platform, centre platform) is a station lay ...
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Double Track
A double-track railway usually involves running one track in each direction, compared to a single-track railway where trains in both directions share the same track. Overview In the earliest days of railways in the United Kingdom, most lines were built as double-track because of the difficulty of co-ordinating operations before the invention of the telegraph. The lines also tended to be busy enough to be beyond the capacity of a single track. In the early days the Board of Trade did not consider any single-track railway line to be complete. In the earliest days of railways in the United States most lines were built as single-track for reasons of cost, and very inefficient timetable working systems were used to prevent head-on collisions on single lines. This improved with the development of the telegraph and the train order system. Operation Handedness In any given country, rail traffic generally runs to one side of a double-track line, not always the same side a ...
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Island Platform
An island platform (also center platform, centre platform) is a station layout arrangement where a single platform is positioned between two tracks within a railway station, tram stop or transitway interchange. Island platforms are popular on twin-track routes due to pragmatic and cost reasons. They are also useful within larger stations where local and express services for the same direction of travel can be provided from opposite sides of the same platform thereby simplifying transfers between the two tracks. An alternative arrangement is to position side platforms on either side of the tracks. The historical use of island platforms depends greatly upon the location. In the United Kingdom the use of island platforms is relatively common when the railway line is in a cutting or raised on an embankment, as this makes it easier to provide access to the platform without walking across the tracks. Advantages and tradeoffs Island platforms are necessary for any station with many th ...
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Turntable (railroad)
In rail terminology, a railway turntable or wheelhouse is a device for turning railway rolling stock, usually locomotives, so that they can be moved back in the direction from which they came. Naturally, it is especially used in areas where economic considerations or a lack of sufficient space have served to weigh against the construction of a turnaround wye. In the case of steam locomotives, railways needed a way to turn the locomotives around for return trips as their controls were often not configured for extended periods of running in reverse and in many locomotives the top speed was lower in reverse motion. In the case of diesel locomotives, though most can be operated in either direction, they are treated as having "front ends" and "rear ends" (often determined by reference to the location of the crew cab). When operated as a single unit, the railway company often prefers, or requires, that a diesel locomotive is run "front end" first. When operated as part of a multiple ...
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Triangle Junction
In railroad structures, and rail terminology, a wye (like the'' 'Y' ''glyph) or triangular junction (often shortened to just "triangle") is a triangular joining arrangement of three rail lines with a railroad switch (set of points) at each corner connecting to each incoming line. A turning wye is a specific case. Where two rail lines join, or in a joint between a railroad's mainline and a spur, wyes can be used at a mainline rail junction to allow incoming trains the ability to travel in either direction, or in order to allow trains to pass from one line to the other line. Wyes can also be used for turning railway equipment, and generally cover less area than a balloon loop doing the same job, but at the cost of two additional sets of points to construct, then maintain. These turnings are accomplished by performing the railway equivalent of a three-point turn through successive junctions of the wye, the direction of travel and the relative orientation of a locomotive or rail ...
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Balloon Loop
A balloon loop, turning loop, or reversing loop ( North American Terminology) allows a rail vehicle or train to reverse direction without having to shunt or stop. Balloon loops can be useful for passenger trains and unit freight trains. Balloon loops are common on tram and streetcar systems. Many streetcar and tram systems use single-ended vehicles that have doors on only one side and controls at only one end. These systems may also haul trailers with no controls in the rear car, and, as such, must be turned at each end of the route. History Balloon loops were first introduced on tram and, later, metro lines. They did not commonly appear on freight railways until the 1960s, when the modernising British Rail system introduced '' merry-go-round'' (MGR) coal trains that operated from mines to power stations and back again without shunting. Tramways On the former Sydney tram system, loops were used from 1881 until the second-generation system's closure in 1961. Initia ...
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Uni-directional Vehicle
A uni-directional vehicle is a vehicle that is normally designed to operate only in the forward direction. While the vast majority of road vehicles are like this, the term generally refers to a train or tram with a distinguishable front and rear end and a single operating cab at the front end. These vehicles often have the capability to operate in reverse, though such operations are limited to low speeds and short distances, such as shunting. Uni-directional vehicles commonly have entry and exit doors on only one side of the vehicle (usually the sidewalk side), although some are equipped with doors on both sides, or operate in opposing traffic flow, to facilitate the use of island platforms. Having doors on only one side allows for an increase in seating on board the vehicle, compared to bi-directional vehicles which have doors on both sides. Because a uni-directional vehicle can only travel in one direction they require special infrastructure for turning around at a terminal ...
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Crossover Switch
In electronics, a crossover switch or matrix switch is a switch connecting multiple inputs to multiple outputs using complex array matrices designed to switch any one input path to any one (or more) output path(s). There are blocking and non-blocking types of cross-over switches. These switches can be microelectromechanical systems, electrical, or optical non-linear optics, and are used in electronics and fiber optic circuits, as well as some optical computers. A banyan switch is one type of cross-over switch. Their complexity depends on the topology of the individual switches in a switch matrix (how wide it is by how many 'plies' or layers of switches it takes), to implement the desired crossover logic. Formula Typical crossover matrices follow the formula: an N×N Banyan switch uses (N/2) log N elements. Other formulas are used for differing number of cross-over layers, and scaling is possible, but becomes very large and complex with large N×N arrays. CAD and AI can be used to ...
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Terminal Station
A train station, railway station, railroad station or depot is a railway facility where trains stop to load or unload passengers, freight or both. It generally consists of at least one platform, one track and a station building providing such ancillary services as ticket sales, waiting rooms and baggage/freight service. If a station is on a single-track line, it often has a passing loop to facilitate traffic movements. Places at which passengers only occasionally board or leave a train, sometimes consisting of a short platform and a waiting shed but sometimes indicated by no more than a sign, are variously referred to as "stops", "flag stops", " halts", or "provisional stopping places". The stations themselves may be at ground level, underground or elevated. Connections may be available to intersecting rail lines or other transport modes such as buses, trams or other rapid transit systems. Terminology In British English, traditional terminology favours ''railway station'' ...
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TMCA Double-ended Super Ambulance(1997)
TMCA may refer to: * Tauro-muricholic acid, a type of bile acid * The Medical Center of Aurora, in Aurora, Colorado * Total Museum of Contemporary Art, in Seoul, South Korea * Toyota Motor Corporation Australia, a subsidiary of Toyota Motor Corporation * TRNAMet cytidine acetyltransferase (TmcA), an enzyme * Tsing Ma Control Area Tsing Ma Control Area (Chinese: 青馬管制區; TMCA) is an area covering Lantau Link and related road networks in the New Territories, Hong Kong, including Tsing Ma Bridge, Kap Shui Mun Bridge, Ma Wan Viaduct (all part of the Lantau Link), Cheu ...
, a subdivision of Hong Kong {{disambiguation ...
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Door
A door is a hinged or otherwise movable barrier that allows ingress (entry) into and egress (exit) from an enclosure. The created opening in the wall is a ''doorway'' or ''portal''. A door's essential and primary purpose is to provide security by controlling access to the doorway (portal). Conventionally, it is a panel that fits into the doorway of a building, room, or vehicle. Doors are generally made of a material suited to the door's task. They are commonly attached by hinges, but can move by other means, such as slides or counterbalancing. The door may be able to move in various ways (at angles away from the doorway/portal, by sliding on a plane parallel to the frame, by folding in angles on a parallel plane, or by spinning along an axis at the center of the frame) to allow or prevent ingress or egress. In most cases, a door's interior matches its exterior side. But in other cases (e.g., a vehicle door) the two sides are radically different. Many doors incorporate locking ...
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Cab (locomotive)
The cab, crew compartment or driver's compartment of a locomotive, or a self-propelled rail vehicle, is the part housing the train driver, fireman or secondman (if any), and the controls necessary for the locomotive or self-propelled rail vehicle's operation. Cab locations On steam locomotives, the cab is normally located to the rear of the firebox, although steam locomotives have sometimes been constructed in a cab forward or camelback configuration. The cab, or crew or driver's compartment of a diesel or electric locomotive will usually be found either inside a cabin attached to a hood unit or cowl unit locomotive, or forming one of the structural elements of a cab unit locomotive. The former arrangement is now the norm in North America for all types of diesel or electric locomotives. In Europe, most modern locomotives are cab units with two cabs, one at each end. However, the locomotives powering some high speed European trains are normally cab units with one cab, an ...
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