France's recently completed Galerie des Janots featured some unexpected challenges: Karst cavities large and small were found throughout the bore as well as two large, uncharted caverns. During excavation with a Main Beam TBM, crews encountered an 8,000 cubic meter cavern studded with stalagmites and a 4,500 cubic meter cavity directly below the bore path. How did the crew overcome the conditions and continue past the voids?

Listen in on our conversation with Detlef Jordan, Robbins Sales Manager Europe, as we discuss the challenges, lessons learned, and recommendations for future tunnels in karst conditions. Find out more on www.TheRobbinsCompany.com or click on this link https://www.youtube.com/watch?v=p2rRzuWoQTg&feature=youtu.be. 47/20.