Particular aspects of the tendering contract SBT3.1 "Tunnel Grautschenhof" / Besondere Aspekte des Ausschreibungsprojekts SBT3.1 Tunnel Grautschenhof

The present invitation to tender for the third tunneling contract of the Semmering Base Tunnel is the last one to complete the tunnel. This contract section has not reached the dimensions of its preceding sections SBT2.1 and SBT1.1 concerning the extent of construction work and time for completion. Nonetheless it emerged to an extremely complex project caused by a gain of knowledge regarding the ground conditions, during the process of preparing the tender documents. This knowledge led to an adjustment containing comprehensive grouting measures and a temporary intermediate construction access via two vertical shafts. Furthermore a sophisticated order of construction sequences for the installation of facilities in the invert and the concrete lining had to be issued, which considered a progressive takeover by subsequent contractors. Additional challenges arose because the tendering documents were adjusted while concurrently the design of documents for the partial modification of the construction permission had to be prepared.