BS EN 13803-2:2006 pdf download
BS EN 13803-2:2006 pdf download.Railway applications——Track — Track alignment design parameters — Track gauges 1435 mm and wider —— Part 2: Switches and crossings and comparable alignment design situations The use of higher values of abrupt change of cant deficiency should, if possible, be avoided. If the use of higher values is unavoidable, for example in close conlunction to switch and crossing layouts, the limiting values shall not exceed those specified in 71.2.
7.2 Limiting values based on the principle of the virtual transition
Some European railway authorities use the principle ci the virtual transition (see Annex E). The limits
applicable for this principle are given in E3.
7.3 MInimum radius of horizontal curves
On all tracks (Including the diverging tracks in switch and crossing layouts) wtiere different railway vehicles operate, the designed minimum radius for any curve shall not be less than 150 m. In the case of a reverse curve, or curves in opposite directions with short intermediate elements, the alignment design shall conform to 8.4.
8 Combinations of horizontal curves
8.1 General
Horizontal curves can be combined to form a reverse curve, curves in the opposite dwections with an intermediate element, a compound curve, and curves in the same direction with an intermediate element. These types of situations are shown in Figure 2. The track elements may have constant curvature (as in Figure 2). but may also be transition curves (for a turnout placed on a transition curve and/or a turnout with variable curvature). In some cases the intermediate element may be a transition curve of sub-standard length, i,e a transition curve that does not conform to the requirements of [NV 13803-1. In practice, such, situations occur in:
the diverging tracks in switch and crossing layouts;
— plaw, tracks abutting switch and crossing layouts:
— plain tracks where it Is impractical to provide full transition curves (typicaly stations and sidings); plain track alignments with Large radii curves:with abrupt changes of curvature.
9.2.2.3 Limiting values for abrupt change of cant deficiency at switch side (8.I) and crossing side
In turnouts with curves of variable curvature the limiting values for abrupt change of cant deficiency at the switch side (J1) and at the crossing side (i) shall be as specified ii Table 2.
9.2.2.4 LimitIng values for cant deficiency (I,,j in the diverging track
The limiting cant deficiency on the diverging tracks of turnouts with curves of variable curvature shall be as
specified in 9.3.4.
9.3 Switch and crossing layouts installed on horizontal curves
9.3.1 General rules
Switch and crossing layouts, comprising of standard switches arid crossings can be installed ii curved tracks. which may be either canted or uncanted The construction of a switch and crossing layout to suit a curved track is achieved by curving standard units to match the curvature of the first designed track. This curvrng alters the curvature of both tracks within practical limits, but the crossing angle at the end of the crossing remams the san’ie. However, there are limits to which standard units can be curved and. consequentiy. a switch and crossing layout may have to be constructed from specially designed switches and crossings components.
The tracks of switch and crossing layouts on horizontal curves shall be designed to the principles and parameters specified in Clauses 6, 7, and 8.
9.3.2 Horizontal radii
When standard switch and crossing units are bent to match the curvature of the flrstty designed track (i/Ri), the curvature of the second track (1/R) is affected. The exact value the curvature of the second track (1/R1) depends on the principles for lengthening and shortening the rails on the closure panel, An approximate estimation of the curvature of the second track CuR) is based on the superposition of curvatures (the small angle approximation).
— for an inside curved switch and crossing.
