New possibilities to reduce track costs on high-speed lines using a bituminous sub-ballast layer

Abstract

The development of structural solutions for high-speed or very high-speed tracks that minimise total life-cycle costs of the system is a key issue to improve the operational profitability of new investments. In opposition to conventional ballasted tracks, slab track solutions can be a cost-effective solution, but only in the cases where the benefits due to the increase in track availability and the reduction of track maintenance offset its much higher construction costs. In the cases where such investment is not feasible, it is worth to evaluate possible structural improvements to ballasted track that allow reducing its maintenance needs without increasing too much its construction costs. This paper evaluates the design requirements and the impact of improving conventional high-speed ballasted tracks using a bituminous sub-ballast layer. It is divided into two main parts: first, the design requirements of the structural solutions with bituminous sub-ballast and its possible benefits on high-speed track deterioration and, second, the evaluation of the economic impact, in terms of construction costs, of using this structural solution material in future Spanish high-speed lines.

Keywords:

• high-speed track
• bituminous sub-ballast
• track design
• track deterioration
• economical impacts

Acknowledgements

The authors would like to thank the support and collaboration of A. Paez, Dr Buonanno, Dr Giambartolomei, Prof. J.G. Rose, Prof. Corrazza, Prof. Malavassi, Dr R. Licciardello, as well as Fundação para a Ciência e Tecnologia Proj. ref. PTDC/ECM/70571/2006.