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Automatic block signaling (ABS), spelled automatic block signalling or called track circuit block (TCB [1]) in the UK, is a railroad communications system that consists of a series of signals that divide a railway line into a series of sections, called blocks. The system controls the movement of trains between the blocks using automatic signals.
Blocks can also trigger signals or other accessories, adding realism or whimsy. Three-rail systems often insulate one of the common rails on a section of track, and use a passing train to complete the circuit and activate an accessory. Many layout builders are choosing digital operation of their layouts rather than the more traditional DC design.
A railway track (CwthE and UIC terminology) or railroad track (NAmE), also known as permanent way (CwthE) [1] or "P Way" BrE [2] and Indian English), is the structure on a railway or railroad consisting of the rails, fasteners, sleepers (railroad ties in American English) and ballast (or slab track), plus the underlying subgrade.
A short-lived alternative was the fish-bellied profile, first used by Thomas Barnes (1765–1801) at Walker Colliery, near Newcastle in 1798, which enabled rails to have a longer span between blocks. These were T-section edge rails, three feet long and laid on transverse stone sleepers. These were still made of cast iron. [18]
Illustration of track circuit invented by William Robinson in 1872 Track circuit transformer on the right, new axle counter on the left (Slovenia). A track circuit is an electrical device used to prove the absence of a train on a block of rail tracks to control railway signals. An alternative to track circuits are axle counters.
Grooved rail, used when track is laid in places traversed by other vehicles or pedestrians. A grooved rail, groove rail, or girder rail is a special rail with a groove designed for tramway or railway track in pavement or grassed surfaces (grassed track or track in a lawn). The head on the right-hand side of the rail bears the vehicle's weight.
Slab track with flexible noise-reducing rail fixings, built by German company Max Bögl, on the Nürnberg–Ingolstadt high-speed line. A ballastless track or slab track is a type of railway track infrastructure in which the traditional elastic combination of sleepers and ballast is replaced by a rigid construction of concrete or asphalt.
There is no legal distinction between a guide rail and a guard rail. According to the US Federal Highway Administration, the terms guardrail and guiderail are synonymous. [5] Several types of roadway guide rail exist; all are engineered to guide vehicular traffic on roads or bridges. Such systems include W-beam, box beam, cable, and concrete ...