Design and construction

Design and construction for the connection in Bologna of the Milan to Naples high-speed rail line, enabling the Milan - Naples high-speed train to cross through the city centre of Bologna.

The project comprises two 6.1-km tunnels for which two Earth Pressure Balance tunnel boring machines of 9.4-m diameter were used.


The excavation of the tunnels in an intensely urbanized context and the heterogeneous ground conditions required a particular methodology in order to minimize the effect on the existing structures and facilities on the surface.


This project highlighted the world's first experiment with grouting to consolidate the earth by offsetting with guided drilling in a curved line. Other innovations include metal rings with gates to connect galleries designed by ACCIONA.


  • Location: Bologna, Italy.
  • Contract type: Design and construction.
  • Infrastructure: Two 6.1 km-tunnels for which two EPB tunnel boring machines with a 9.4-m diameter were used.
  • Year of project completion: 2007

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