Settlement behaviour of hybrid asphalt-ballast railway tracks.

• Large-scale phased cyclic loading of asphaltic railway tracks. • Investigation of asphalt railroad performance at a subgrade transition zone. • Asphaltic track shown to outperform ballast track in terms of settlement and subgrade pressure reduction. The use of structural asphalt layers inside ballasted railway tracks is attractive because it can increase track bending stiffness. Therefore, for the first time, this paper investigates the long-term settlement characteristics of asphaltic track in the presence of a subgrade stiffness transition zone. Phased load cyclic compression laboratory tests are performed on a large-scale hybrid asphalt-ballast track, supported by subgrade with varying stiffness. It is found that an asphaltic layer acts as a bridge to shield the subgrade from high stresses. It is also found that the asphalt reduces track settlement, and is particularly effective when subgrade stiffness is low. [ABSTRACT FROM AUTHOR]