In 2002 the first metro line (Ligne A) of the city of Rennes was put into operation. It runs fully automatically over a distance of 9 kilometers and transports around 140,000 passengers daily. Preparations for Ligne B in 2012 signaled the beginning of the expansion of the municipal local public transport system of Brittany's capital. Running from the northeast to the southwest of the city and with a total length of almost 14 kilometers, Ligne B will increase the attractiveness of public transport and thus of the city as a whole for residents and visitors.
In 2014 Herrenknecht delivered a large-diameter EPB shield (Ø 9,410 mm) for the construction of 8.5 kilometers of double-track tunnel under the city center of Rennes. After the christening of the machine in December 2014, in January 2015 "Elaine" bored into the underground for the first time. As she journeyed northeastward, the metro stations she was to pass through could not be used for supply and disposal. The entire tunnel logistics had to be handled from the launch shaft. This was a major challenge for the French tunnelling specialists, in particular because of the very windy route with curve radii of up to 180 meters.
During tunnelling the geology proved to be much tougher than predicted. In close coordination with the Herrenknecht engineers, those responsible on site therefore decided to reduce the opening angle of the cutting wheel and to install a stone crusher. These measures and the competence of the site crew ensured that the tunnel had already grown to a length of almost 7 kilometers by October 2017. The construction team celebrates the final breakthrough on February 28, 2018.