A key milestone in Jinan's urban infrastructure was achieved on March 17 with the completion of the upper deck of the Huanggang Road Yellow River Tunnel.

Spanning approximately 5.75 kilometers, the tunnel includes a 3.3-km shield section and features a single-tube, double-deck design. Constructed with the Shanhe tunnel boring machine – the world's largest of its kind with an excavated diameter of 17.5 meters – the project accommodates six lanes of traffic across two levels (three lanes on each level), designed for speeds of 60 km per hour, with clearance for buses and emergency vehicles.

The newly completed upper deck forms the structural foundation of the top traffic level, with slabs spanning 13 meters and 0.7 meters thick, requiring more than 30,000 cubic meters of concrete.

The work was conducted in a confined underground space, where teams needed to install complex embedded components with millimeter-level precision while coordinating ongoing tunneling and material transport. To improve efficiency, engineers introduced 12 hydraulic integrated mobile trolleys, facilitating an assembly-line construction process. A dedicated transport lane on the lower level ensured seamless material movement without disrupting operations.

As a crucial link between Jinan's main urban area and the Jinan Start-up Area for Growth Drivers Transformation, the tunnel is expected to significantly improve cross-river connectivity. Once open, the travel time across the Yellow River will be cut from 40 minutes to just four minutes.

The upper deck of the Huanggang Road Yellow River Tunnel is completed on March 17 in Jinan. [Photo/Qilu Website]

Workers carry out construction within the world's largest-diameter underwater shield tunnel in Jinan. [Photo/Qilu Website]