Core Points - The Tangshan Road Tunnel, part of the Qingyin Expressway expansion project, has officially completed its main construction phase as of September 22, entering the road surface and decoration stage [2] - The tunnel measures 1551 meters in length, features dual bi-directional tunnels with 8 lanes, and has a maximum excavation span of 31.8 meters, making it the largest municipal traffic tunnel in China by maximum span cross-section [2]