Standardisation needs for the design of underground structures

Tunnel projects in Europe form a large portion of the infrastructure market, and there is continuous demand for the construction of new tunnels. Road and railway tunnels play a central role in the modern economy, with thousands of people and tons of goods passing through them every day. Failure of such critical links may lead to significant disruption of large parts of the European transportation system. However, underground structures and particularly tunnels are unique structures. Their key design considerations and structural behavior 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.

In view of the above fact and the strategic importance of the construction industry in the European market, the Joint Research Centre (JRC) of the European Commission started in 2017 activities on the assessment of standardisation needs for the design of underground structures. The JRC Technical Report published in 2019 delineates that the development of design standards for tunnels and underground structures is certainly feasible (at least for typical configurations) and that it would be advantageous to foster harmonisation of design rules between countries. It appears suitable that the concept of new standards or guidelines for the design of tunnels shall be developed in line with the Eurocodes and delineate how to complete and/or restrict their use for tunnels without limiting the required flexibility, having in mind the specificity and diversity of tunnel design. In parallel, it would be beneficial that the concept will be consistent with the new developments in the second generation of the Eurocodes currently under development and expected to be published soon after 2020.