The project has a total length of nearly 5.5km, of which Cu Mong Tunnel itself is approximately 2.6km long, located on the Quy Nhon–Chi Thanh Expressway section with two traffic lanes. It is one of four major tunnels under the road tunnel project through Deo Ca, including Deo Ca, Co Ma, Cu Mong, and Hai Van 2.
Since being put into operation in 2019, the tunnel has reduced travel time across the mountain pass from 30 minutes to just six minutes, significantly improving traffic safety.
In the immediate phase, the project will expand the roadway from two to four lanes, with a roadbed width of 22m. The right tunnel tube will undergo road surface upgradation and adjustments to the tunnel equipment system to suit one-way operation with two lanes. The left tunnel tube will be completed with remaining items, including the tunnel lining, cement concrete road surface, drainage system, electrical and mechanical systems, fire prevention and fighting systems, and operational facilities.
Bridges along the route will be upgraded to a six-lane scale. The existing bridge will be widened on the right side from 10.5m to 14.75m to accommodate three lanes. In addition, a new parallel bridge unit will be constructed, 0.5m from the existing bridge, with a width of 14.75m.
