Viability of using a bituminous sub-ballast layer on high-speed ballasted tracks

Resumé

The design of higher quality infrastructures reducing its life cycle costs is a major priority to increase the profitability of high-speed railway lines. The experience gained so far has evidenced the influence of track configuration on its maintenance costs. Recent railway research has shown that to fulfil a reduction of those costs one should act optimizing both the resiliency of the fastening system and the subgrade-sub-ballast system. With reference to this last aspect, the aim of this paper is to expose the first results obtained on a research project carried out by the authors concerning the viability of using a bituminous mix sub-ballast layer on the new Spanish high-speed lines. The interest of this solution to increase long-term performance of the track is discussed based on the available experience. Furthermore, the results of a parametric study evidences in what terms this solution can be technically feasible to reduce maintenance costs and increase service life of ballasted highspeed tracks.