The Kim Dong – Giai Phong Underpass Project commenced in October 2022 with a total investment of VND 778 billion. The project is managed by the Hanoi Traffic Construction Investment Project Management Board. Vinh Hung serves as the contractor responsible for supplying and installing the waterproofing system.

The underpass has a total length of 890 m, including a 140 m enclosed tunnel section and 320 m of open tunnel section. Each direction accommodates two lanes within the tunnel and three lanes outside the tunnel, with a lane width of 3.5 m. As Hanoi’s fifth underpass project, following Kim Lien, Trung Hoa, Thanh Xuan, and Le Van Luong, it plays a key role in alleviating congestion at the southern gateway of the capital and completing the Ring Road 2.5 network, particularly around the Giap Bat freight station area.

Waterproofing is a critical component of the project, protecting the tunnel base slab, walls, and roof slab from water ingress, thereby enhancing the structure’s durability, appearance, and long-term performance.

The waterproofing system consists of a 1.2 mm HDPE waterproofing membrane fully wrapping the base slab, while the tunnel walls and roof are protected with post-applied bituminous waterproofing membranes. A 3 cm XPS protection board is installed externally to safeguard the waterproofing layer from damage caused by backfill materials. Additional waterproofing measures include waterstops, hydrophilic rubber strips, joint sealants, and reinforcement sheets at critical locations such as expansion joints and construction joints, forming a fully watertight system that prevents groundwater infiltration.