X-shaped sleepers improve load transfer under impact on railway tracks

Researchers at Wuhan University of Technology have discovered that an X-shaped railway sleeper can change how impact loads travel through ballasted track—reducing peak sleeper acceleration by 23% and average ballast contact forces by 40% compared to conventional I-shaped sleepers.

Ballasted track accounts for the vast majority of railway lines worldwide, with wheel-rail impact representing one of its primary threats. Track irregularities caused by rail and wheel wear, uneven settlement, or joint defects cause wheels to momentarily lose contact with the rails before striking back at high velocity, generating impact forces that can reach three to four times the static wheel load.

"Under impact loading, conventional I-shaped sleepers create sparse but highly concentrated force chains beneath the sleeper, focusing stress on a small number of ballast particles and accelerating ballast degradation," explains the study's first author, Cheng Chen, an associate professor in geotechnical engineering. "Our proposed X-shaped sleeper, with its distinctive bidirectional V-shaped configuration, significantly increases the contact area with the ballast. However, the mechanical behavior and load transfer mechanisms at the X-shaped sleeper-ballast interface under impact loading remained unclear—this is precisely the key question our study set out to address."

The research team found that, unlike the sparse, high-intensity force chains formed beneath conventional I-shaped sleepers, the unique geometry of the X-shaped sleeper breaks down impact loads into a dense, uniform network of force chains.

"This spatially diffused load transfer mechanism effectively reduces stress concentrations, enhances interlocking between ballast particles, and allows impact energy to be dissipated across a broader area—significantly improving the overall stability and impact resistance of the trackbed," shares Chen.

"Under impact loading, conventional I-shaped sleepers tend to generate localized high-intensity force chains that accelerate ballast breakage."

The X-shaped sleeper, by contrast, reconstitutes the force chain network, achieving a fundamental shift from concentrated load-bearing to spatial diffusion. "We hope our research inspires further exploration to enhance trackbed stability, ultimately delivering safer and more comfortable railway journeys for the public," adds Chen.

The team's findings are published in the KeAi journal Journal of Railway Science and Technology.

Contact author details: 

Cheng Chen, School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan, Hubei, China. chengchen87@whut.edu.cn

Funder:

The financial supports from the National Natural Science Foundation of China (51708438) are gratefully acknowledged.

Conflict of interest:

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

See the article: 

Chen, C., et al., Numerical Study of Load Transfer in Conventional and X-Shaped Sleeper-Ballast Systems under Impact Loading, Journal of Railway Science and Technology, Volume 2, Issue 1, 2026, Pages 27-40, https://doi.org/10.1016/j.jrst.2026.02.001.