Hardness, Fouling, Life-Cycle, and Ballast Requirements for High-Speed and Heavy-Haul Railways

Results from tests performed on ballast used in the Greek network, as well as a new method for the estimation of ballast fouling as a function of ballast hardness are presented in the present paper. Stresses that develop under the seating surface of the sleeper and that are transmitted to the ballast, influence maintenance intervals and cost. Ballast hardness influences the fouling and consequently the life-cycle of the material laid at the ballast-bed. This leads to the determination of a minimum quality for the technical specifications in relation to traffic conditions (daily tonnage). The present paper discusses these issues and results from the research programs performed on the Greek railway net-work.