As part of the Regional Road dual carriageway, Harrison Geotechnical was asked to help with the design and construction of twin tunnels.

The geology in this area comprised limestone rock, which was thought to be essentially stable but known to be at risk from voids, faulting and inclusions. We undertook a surface-down geotechnical investigation using geophysics and boreholes, and then were responsible for the geotechnical design and monitoring aspects of the project.