Than Vu Tunnel was considered one of the most challenging and technically complex mountain tunnels on the North – South Expressway. The waterproofing system was installed to prevent groundwater infiltration into the tunnel lining, protect electrical and traffic control m equipment, and enhance the long-term durability of the structure.

The waterproofing system was installed between the shotcrete layer and the final tunnel lining and consisted of two layers: an outer nonwoven geotextile layer and an inner waterproofing membrane.

In July 2024, Vinh Hung completed waterproofing works covering 2.3 km (approximately 65,000 m²) across both left and right tunnel bores.