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Railway signalling (BE), or railroad signaling (AE), is a system used to control the movement of railway traffic. Trains move on fixed rails , making them uniquely susceptible to collision . This susceptibility is exacerbated by the enormous weight and inertia of a train, which makes it difficult to quickly stop when encountering an obstacle.
Signalling in the UK uses route signalling. Most railway systems around the world, however, use speed signalling. Under route signalling, the driver is informed which route has been set by an illuminated Junction Indicator mounted on the signal post. The signal will display a restrictive aspect to make the driver reduce the train's speed.
Most rail routes have a sort of natural block layout inherent in the layout of the railway stations. This provides the ability to implement a set of blocks using manual signalling based at these locations. In this case, the station operator places a flag indicating a train has just left the station, and removes it only after a fixed time.
Behind the signal head is placed a dark backing or target, which helps improve signal visibility in bright ambient lighting. Target designs vary, but are usually round or oval, depending on the layout of the signal lamps. For each type of signal there are usually a range of target dimensions that can be chosen by the individual railroad company.
CBTC is a signalling standard defined by the IEEE 1474 standard. [1] The original version was introduced in 1999 and updated in 2004. [1] The aim was to create consistency and standardisation between digital railway signalling systems that allow for an increase in train capacity through what the standard defines as high-resolution train location determination. [1]
Standards for North American railroad signaling in the United States are issued by the Association of American Railroads (AAR), which is a trade association of the railroads of Canada, the US, and Mexico. Their system is loosely based on practices developed in the United Kingdom during the early years of railway development. However, North ...
On a rail transport system, signalling control is the process by which control is exercised over train movements by way of railway signals and block systems to ensure that trains operate safely, over the correct route and to the proper timetable.
CTC consolidates train routing decisions that were previously carried out by local signal operators or the train crews themselves. The system consists of a centralized train dispatcher's office that controls railroad interlockings and traffic flows in portions of the rail system designated as CTC territory. One hallmark of CTC is a control ...