# Impact of Geometric and Petrographic Characteristics on the Variability of LA Test Values for Railway Ballast

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## Abstract

The Los Angeles test is one of the few mechanical test methods that provides information on the quality of railway ballast. However, the Los Angeles value is subject to large variability. Since important economic decisions depend on this value, the reasons for its variability are investigated. An extensive series of tests using four types of rock as well as an in-depth analysis of particle geometry and petrography are carried out. The impact of particle characteristics on the test results is investigated. The deviation of the petrographic composition within a given sample turns out to have a considerable impact on the Los Angeles test results, whereas the influence of the respective deviation of particle geometry is relatively small. The latter effect only comes into play in connection with petrographically homogeneous rock types. The distribution of the geometric features is similar in almost all of the rock types investigated. Due to the large deviation in particle shape and angularity, the sample mass of 10 kg (as provided in the standards EN 1097-2 and EN 13450) is not found to be representative. The necessary number of test repetitions in order to exclude the effect of deviation of particle geometry is estimated. The one result parameter according to the standard, the Los Angeles value, does not allow for discriminating between the amount of abrasion and the fragmentation occurring during the test. An additional result parameter for the estimation of the fragmentation rate is therefore proposed.

## Keywords

Attrition Abrasion Fragmentation Particle shape Railway ballast LA test## Notes

### Acknowledgements

The authors thank the ÖBB Infrastruktur AG for providing the samples, and the ÖBB Stab Forschung und Entwicklung for financing the Petroscope 4D^{®} measurement device.

## References

- Aschenbrenner B (1956) A new method of expressing particle sphericity. J Sediment Res 26:15–31 Google Scholar
- ASTM E177-90a (1992) Standard practice for use of the terms precision and bias in ASTM test methods. ASTM standards on precision and bias for various applications, 4th edn Google Scholar
- Bach H, Kuttelwascher C, Latal C (2012) Alternative Prüfverfahren zur Qualitätssicherung von Gleissschotter. ZEVRail 136(3):176–185 Google Scholar
- Benjamini Y, Hochberg Y (1995) Controlling the false discovery rate: a practical and powerful approach to multiple testing. J R Stat Soc B 57:289–300 Google Scholar
- Deutsche Bahn (German Railways) (2006) Technische Lieferbedingungen Gleisschotter Google Scholar
- DIN ISO 5725-1 (1997) Accuracy (trueness and precision) of measurement methods and results—Part 1: general principles and definitions Google Scholar
- Dvoretzki A, Kiefer J, Wolfowitz J (1956) Asymptotic minimax character of the sample distribution function an of the classical multinomial estimator. Ann Math Stat 27(3):642–669 CrossRefGoogle Scholar
- EN 933-3 (2012) Tests for geometrical properties of aggregates—Part 3: determination of particle shape—flakiness index Google Scholar
- EN 933-4 (2008) Tests for geometrical properties of aggregates—Part 4: determination of particle shape—shape index Google Scholar
- Erichsen E, Ulvik A, Saevik K (2011) Mechanical degradation of aggregate by the Los Angeles-, the micro-deval- and the Nordic test methods. Rock Mech Rock Eng 44:333–337 CrossRefGoogle Scholar
- EUREKA (2001) Petroscope—an optical analyser for construction aggregates and rocks. Technical report 2569, Brussels Google Scholar
- EUREKA (2005) Petroscope II. Technical Report 3665, Brussels Google Scholar
- Hofer V, Bach H (2012) Statistical monitoring for continuous quality control of railway ballast. Eur J Oper Res, submitted Google Scholar
- Hofer V, Pilz J, Helgason TS (2006) Statistical classification of different petrographic varieties of aggregates by means of near and mid infrared spectra. Math Geol 38(7):851–870 CrossRefGoogle Scholar
- Lee J, Smith M, Smith L (2007) A new approach to the three-dimensional quantification of angularity using image analysis of the size and form of coarse aggregates. Eng Geol 91:254–264 CrossRefGoogle Scholar
- Liu H, Kou S, Lindqvist P-A (2005) Microscope rock texture characterization and simulation of rock aggregate properties. Technical report SGU project 60-1362/2004, Geological survey of Sweden Google Scholar
- Lung-Yut-Fong A, Lévy-Leduc C, Cappé O (2012) Homogeneity and change-point detection tests for multivariate data using rank statistics. arXiv:1107.1971 [math.ST]
- ÖBB (Austrian Railways)—Infrastructure Department (2002) Richtlinie für das Entwerfen von Bahnanlagen—Hochleistungsstrecken (directive for the design of railway infrastructure—High speed railways), Vienna Google Scholar
- ÖBB (Austrian Railways)—Infrastructure Department (2007) BH 700: Technische Lieferbedingungen für Oberbauschotter (engineering specifications for delivery of railway ballast) Google Scholar
- ON EN 1097-2 (2006) Tests for mechanical and physical properties of aggregates—Part 2: methods for the determination of resistance to fragmentation. Austrian Standards Institute, Vienna Google Scholar
- ON EN 13450 (2004) Aggregates for railway ballast. Austrian Standards Institute Google Scholar
- Powers MC (1953) A new roundness scale for sedimentary particles. J Sediment Res 23(2):117–119 Google Scholar
- Raymond G, Bathurst R (1985) Repeated-load response of aggregates in relation to track quality index. Can Geotech J 31(4):547–554 CrossRefGoogle Scholar
- Röthlisberger F, Däppen J, Kurzen E, Würsch E (2005) Los Angeles Prüfung für Gleisschotter—Aussagekraft und Folgerung. Eisenbahntechnische Rundschau, pp 355–361 Google Scholar
- Tolppanen P, Stephansson O, Stenlid L (2002) 3-d degradation analysis of railroad ballast. Bull Eng Geol Environ 61:35–42 CrossRefGoogle Scholar
- Wieden P, Augustin H (1977) Versuche zur Verbesserung des Los Angeles Tests. Bundesministerium für Bauten und Technik Google Scholar
- Zingg T (1935) Beitrag zur Schotteranalyse. Schweiz Mineral Petrogr Mitt 15:39–140 Google Scholar