ABSTRACT
In urban context, the improvement of rail infrastructures leads to develop underground railways by means of bored and artificial tunnels, aimed at respecting the environment and giving back urban spaces to citizens, with a particular attention to city centers and historical sites. Different design solutions can be adopted depending on depth of excavation, overburden, ground geotechnical characteristics, water table level, logistic and site layouts, potential issues with construction sequences and line disruptions, available techniques and equipment proposed by the contractors and other several variables. The aim of the present paper is to provide an overview of different design solutions and construction approaches for artificial tunnels, with reference to the ones designed and built in Italy, as the majority of the railway lines and hubs have been strongly renovated during the last years. Then, by highlighting advantages and disadvantages of each alternative, the best practices for artificial railway tunnels will be defined.
