Tunnel projects in Europe form a large portion of the infrastructure market, and there is continuous demand for the construction of new tunnels. Underground structures and particularly tunnels are unique structures. Their key design considerations and structural behaviour are different from other structures, such as buildings and bridges, as the main bearing element in tunnels is the surrounding soils and rocks.
Despite the unique characteristics of tunnel design, there are no currently available European tunnel design standards or harmonised guidelines at European level. Thus tunnel design in Europe is being carried out based on national knowledge and experience with the use of industrial/client standards and guidelines, as well as with parts of the Eurocodes. However, the scope of the first generation of the Eurocodes covers buildings and some other civil engineering works, e.g. bridges, towers, masts, chimneys, silos, tanks, pipelines. There are no parts devoted to the design of tunnels, as the Eurocodes do not include explicitly all underground structures.
In view of the above fact and the strategic importance of the construction industry in the European market, the JRC started in 2017 activities on the assessment of standardisation needs for the design of underground structures. The initiative was launched in the framework of the series of Administrative Arrangements between DG JRC and Directorate-General (DG) for Internal Market, Industry, Entrepreneurship and SMEs (DG GROW) of the European Commission on support to policies and standards for sustainable construction. The activities on standardisation needs for underground structures are supported by an Expert Group on the design of underground structures convened by the JRC.