Boring of the tunnel by the tunnel boring machine "Bertha" began on July 30, 2013, with the roadway initially scheduled to open in December 2015. Tunneling stopped on December 6, 2013, after the boring machine struck a steel pipe, which obstructed its path into the route. Investigations revealed that the machine had struck a pipe which had been installed in 2002 as a part of an exploratory well used to measure groundwater as part of the planning phases for the project. Boring resumed briefly on January 28–29, 2014, stopping again due to damage to the seal system which protects the machine's main bearing and damage to several of the cutting blades. This caused a two-year delay as it was necessary to dig a vertical shaft recovery pit from the surface in order to access and lift the cutterhead for repair and partial replacement.