Environmental impact assessment of an in-service road tunnel during the enlargement project in Vietnam

The most challenging task of existing tunnel enlargement projects is the conservation ofnormal transport activities during the construction. Started in February 2016, Hai Van road tunnel enlargement project is the first time in Vietnam where the evacuation tube has been widened to become another main tube by NATM technology while the main tube is always in use. In this paper, the environmental impact of the project was assessed via the monitoring data of the soil, water, and air environment at different locations at the construction site. Favourable measured results showed the appropriateness of the design and construction solutions in minimizing the bad environmental impacts of a tunnel enlargement project in Vietnam.