In Italy, the largest tunnel boring machine ever used in Europe successfully completed its drive at the Santa Lucia Tunnel on June 8, 2020. The supersize borer (Earth Pressure Balance Shield, diameter 15.87 m) made by Herrenknecht in Schwanau, Germany, dug 7.5 km of highway tunnel through the Apennines.
The large three-lane Santa Lucia Tunnel is a key project in the expansion of the A1 highway between Bologna and Florence. Thanks to optimized routing on the previously winding highway, the efficient tunnel will reduce the likelihood of accidents as well as travel times and thus the gasoline and diesel consumption of tens of thousands of cars and trucks a day.
Following the specifications of customer Pavimental S.p.A., Herrenknecht designed and manufactured an EPB machine (Earth Pressure Balance Shield). Working closely with the contractor, the engineers tailored the tunnel boring machine to the specific requirements of the project. Among other things, they implemented a comprehensive warning and protection system to reliably protect the site crew against potential dangers from the methane gas deposits predicted underground during the advance.
Following just 12 months of design and assembly, in August 2016 the EPB Shield was punctually ready at Herrenknecht in Schwanau for formal acceptance by the contractor and representatives of the client, Autostrade per l’Italia S.p.A. After the start of tunnelling in July 2017, the Pavimental miners drove up to 122 m of tunnel per week through the Apennine mountain range with the 4800 tonne colossus. During the long drive over 7.5 km, the EPB machine excavated a total of around 1.5 million m³ of soil and rock. This corresponds to almost two thirds of the volume of the Cheops pyramid.
Italian contractors and infrastructure projects are known and respected worldwide for very large tunnel boring profiles and complex tunnel geologies. With the production of the Santa Lucia machine, Herrenknecht beat the existing European record for TBM diameters of 15.55 m. It had been held since 2010 by the Herrenknecht EPB Shield for the Sparvo tunnel, also for the expansion of the A1 motorway in Italy.