Bertha Cut
A TriAx geocomposite enabled construction of a road across highly saturated, and very weak, ground to provide access to a new community being built on the outskirts of Perth, Scotland.
Benefits
- Enabling road construction over weak soils, with average CBR values of less than 0.5%
- Delivering a technically-viable alternative to conventional approaches
A section of the road between the A85 and Bertha Park runs in a cutting through an area of weak soils, with ground water lying above road level. Construction of a conventional capping layer, forming the foundation of the temporary access road and the permanent pavement, was unsuccessful, so an alternative was needed.
Field trials demonstrated that an aggregate layer, mechanically stabilised by incorporating a geocomposite of TriAx geogrid backed with a non-woven geotextile, combined with a new drainage regime, would overcome the extremely challenging ground and groundwater conditions. This layer provided sufficient support to carry light construction traffic and also allowed the permanent road to be built above without any issues.
