Abstract:In recent years, the traffic congestion in Damao Tunnel of the G98 Hainan Isle Ring Expressway has become increasingly prominent, and the traffic accident rate remains high. The existing problems of the current Damao Tunnel are investigated and surveyed from the multiple angles. The relationship between the planned Sanya No.II Ring Expressway and the reconstruction and extension of Damao Tunnel is interpreted. And combined with the highway network planning and the site construction conditions in Sanya, three overall schemes for the reconstruction and extension of Damao Tunnel are compared and demonstrated, which provides the design reference for the reconstruction and expansion engineering of mountain tunnels in the high-grade highways.