LAUSR

ABSTRACT Ballasted track is the conventional type of track structure around the world. Although it has several benefits, it often requires notable maintenance to ensure adequate operation. The trackbed design plays a major role on the structural performance of the track, and consequently on its maintenance. Apart from slab track, which requires significant investments, alternative solutions such as the use of asphalt underlayment with ballasted tracks can lead to a satisfactory balance between investment and maintenance. This paper investigates the use of asphalt underlayment in trackbed using a numerical model of the falling weight deflectometer (FWD), for different subgrade moduli. This is to investigate the resulting dynamic sleeper support stiffness due to FWD loading to develop a design chart for trackbed with asphalt underlayment. The paper also illustrates the use of these design charts on theoretical design scenarios and carry out a comparison with other international practices.