The tunnel is 2.2 kilometres long and was constructed using Austrian tunnel boring technology.
The breakthrough is a major milestone towards the goal of full completion of the 78.5-kilometre-long Cam Lam-Vinh Hao Expressway by the end of April 2024.
About 21 kilometres of the Cam Lam-Vinh Hao Expressway are expected to be put into use by the end of this year.
Cam Lam-Vinh Hao is one of the three sections of the North-South Expressway project implemented under public-private partnerships, with total capital of nearly 8 trillion VND (337.7 million USD).
It runs through three provinces: Khanh Hoa (5 kilometres), Ninh Thuan (63 kilometres) and Binh Thuan (12 kilometres).