BEIJING, Aug. 21 -- China drilled a tunnel through for expressway transport in Beijing on Monday. It is the longest expressway tunnel in the country created using the shield-tunneling method.

With a total length of 7.4 km, the tunnel project is designed to have a two-way six-lane expressway on the middle level, smoke vents on the upper level and evacuation and rescue routes on the lower level, according to the Beijing Capital Highway Development Group Co., Ltd., which is implementing the project.

The tunnel is part of Beijing's east sixth ring road project. The deepest section of the tunnel, which is 75 meters underground, is the deepest underground tunnel in Beijing. In June, the west tunnel of the project was the first to be drilled through. The east tunnel was just drilled through on Monday.

With an excavation diameter of 16.07 meters and a length of about 145 meters, the shield-tunneling machine adopted in the project is independently designed and made by Chinese enterprises. It weighs 4,500 tonnes.

The tunnel project has helped make way for more space on the ground for promoting industrial development and planning large parks, contributing to the high-quality development of Beijing's sub-center Tongzhou District and coordinated transport development in the Beijing-Tianjin-Hebei region.