Wheel-rail impact is a major threat to ballasted track, which accounts for the majority of railway lines worldwide. Such impacts can generate forces three to four times the static wheel load, accelerating ballast degradation and compromising safety. Conventional I-shaped sleepers tend to concentrate stress through sparse, high-intensity force chains, but the mechanical behaviour of alternative designs under impact loading has remained unclear.
Here, the researchers propose an X-shaped sleeper with a bidirectional V-shaped configuration. Using numerical simulations, they compared its performance with that of conventional sleepers. The results show that the X-shaped geometry breaks down impact loads into a dense and uniform network of force chains, significantly reducing stress concentrations and enhancing interlocking between ballast particles. Peak sleeper acceleration is reduced by 23% and average ballast contact forces by 40%, indicating a fundamental shift from concentrated load-bearing to spatial diffusion.
This work provides a new understanding of load-transfer mechanisms at the sleeper-ballast interface and opens a promising route to improving track durability and passenger comfort. The work entitled “Numerical Study of Load Transfer in Conventional and X-Shaped Sleeper-Ballast Systems under Impact Loading” was published on Journal of Railway Science and Technology (published on Feb. 28, 2026).
DOI：10.1016/j.jrst.2026.02.001