EIFFAGE entrusted INNOGEO with the geophysical survey for the Brittany-Loire Valley High-Speed Line Project between Le Mans and Rennes. The investigations started in December 2012 and are set to continue in 2013 and 2014. They consist mainly of microgravimetric and electromagnetic EM34 measures to search for old mining galleries (iron, lead…) and cavities or limestone dissolution areas.