The road surface comprises several layers, with each performing different functions. The first layer made from concrete serves to level the substrate, while the second, supporting layer of mastic asphalt absorbs the vehicle loads without de-forming. The third layer, referred to as the wear layer, ensures optimum tyre grip. 

Some 6.4 million vehicles (total in both directions) passed through the Gotthard Tunnel in 2019. This figure included 640,000 lorries. In future, this traffic volume will be shared between the two tunnels. Over the course of its 20-year service life, the installed road surface will thus withstand around 64 million vehicles.