The Durraburra-Newlands rail line near Collinsville was experiencing deflection above a set of culverts, where water migration beneath the structure had caused erosion, void formation and a reduction in the loadbearing capacity of the underlying soils. Aurizon required a controlled ground engineering solution capable of filling subsurface voids, improving support beneath the culvert base slab and limiting further deflection under rail loading, while maintaining strict lift tolerances to protect the rail structure throughout the works.