BS EN 13848-5-2008 pdf download.Railway applications Track – rack geometry quallty Part 5 : Geometric quality levels.
— by track contractors;
— by regulatory authorities;
— for research purposes.
The values stated in this European Standard are based on the values prescribed by various European railways. Furthermore, this standard takes into account, as far as possible, the previous studies made on this topic:
— Annex C of EN 14363:2005;
— 7’S! for high-speed line infrastructure;
— ORE Question B55 report N.o 8 (1983).
7 Assessment of track geometric quality
All the parameters as defined in EN 13848-1 are encompassed in this European Standard; their respective importance and their influence on vehicle behaviour are described in Annex A.
Three indicators can describe the track geometric quality:
— extreme values of isolated defects;
— standard deviation over a defined length, typically 200 m;
— mean value.
NOTE 1 Consideration should be given to successions of isolated defects because they could generate resonance effects, and to combinations of defects in several parameters at the same location (see Annex A).
Three main levels have to be considered:
Immediate Action Limit (1AL): refers to the value which, if exceeded, requires taking measures to reduce the risk of derailment to an acceptable level. This can be done either by closing the line, reducing speed or by correction of track geometry;
— Intervention Limit (IL): refers to the value which. if exceeded, requires corrective maintenance in order that the immediate action limit shall not be reached before the next inspection;
— Alert Limit (AL): refers to the value which, if exceeded, requires that the track geometry condition is analysed and considered in the regularly planned maintenance operations.
These values are given as a function of speed, which is an important factor for the evaluation of track geometry quality. Parts 2, 3 and 4 of EN 13848 give measuring methods for track geometry whereby track geometry quality can be assessed.
The values in the tables are given for a loaded track as defined in EN 13848-1. When the measurements are made on unloaded track, the difference in the measured values that may result need to be taken into account.
The normative part of the standard gives IALs for isolated defects and for mean track gauge.
The informative part of this European Standard gives !Ls and ALs for isolated defects and mean track gauge. and 4L5 for standard deviations.
The track geometry limits AL. IL and JAL differ from the 3 vehicle acceptance levels QN1. QN2 and QN3 used in EN 14363. More particularly QN3 is quite different from IAL because, according to EN 14363, it characterises track sections which do not exhibit the usual track geometry quality. Quality level QN3, however, does not represent the most adverse but still tolerable maintenance status which still allows regular train operations.
NOTE 2 A further quality level of track geometry can be used for track works acceptance (see EN 13231-1).
NOTE 3 The intervention limit depends on the corrective maintenance policy, the frequency of inspection and defect growth rate
8 Immediate action limits
8.1 Introductory remarks
The immediate action limit values given in this standard are derived from experience and from theoretical considerations of the wheel-rail interaction as physical tests with different vehicles up to the point of derailment are not practicable.
Exceeding these immediate action limit values requires specific measures to be implemented to reduce the risk of derailment or other hazards to an acceptable level.
The wavelength range D3 is not taken into account in the following, as it is not directly linked with safety, but more with vehicle ride quality.
The immediate action limits given in the following tables and figures are normative. With the exception of track gauge, all values stated are absolute.
8.2 Track gauge.BS EN 13848-5-2008 pdf download.
BS EN 13848-5-2008 pdf download
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