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Track geometry is concerned with the properties and relations of points, lines, curves, and surfaces [1] in the three-dimensional positioning of railroad track. The term is also applied to measurements used in design, construction and maintenance of track.
A track geometry car (also known as a track recording car) is an automated track inspection vehicle on a rail transport system used to test several parameters of the track geometry without obstructing normal railroad operations. Some of the parameters generally measured include position, curvature, alignment of the track, smoothness, and the ...
The Hallade method, devised by Frenchman Emile Hallade, is a method used in track geometry for surveying, designing and setting out curves in railway track. [1] It involves measuring the offset of a string line from the outside of a curve at the central point of a chord. In reality, string is too thick to provide a clear reading and breaks ...
Measurement of track spacing from the rail head to rail head. By definition, the track spacing is given from centre to centre of a rail track. For an actual construction the distance is measured from the inside of a rail head to the matching one of the other track. As far as both tracks have the same gauge this is the same distance.
Too tight a 'crest' curve could result in the train leaving the track as it drops away beneath it; too tight a 'trough' and the train will plough downwards into the rails and damage them. More precisely, the support force R exerted by the track on a train as a function of the curve radius r, the train mass m, and the speed v, is given by
The design pattern for horizontal geometry is typically a sequence of straight line (i.e., a tangent) and curve (i.e. a circular arc) segments connected by transition curves. The degree of banking in railroad track is typically expressed as the difference in elevation of the two rails, commonly quantified and referred to as the superelevation.
Track geometry is three-dimensional geometry of track layouts and associated measurements used in design, construction and maintenance of railroad tracks. The subject is used in the context of standard, speed limits and other regulations in the areas of track gauge , alignment, elevation, curvature and track surface.
The American gauges converged, as the advantages of equipment interchange became increasingly apparent. Notably, all the 5 ft (1,524 mm) broad gauge track in the South was converted to "almost standard" gauge 4 ft 9 in (1,448 mm) over the course of two days beginning on 31 May 1886. [21] See Track gauge in the United States.