NORTH TUNNELING SHIELD IS LAUNCHED ON ITS WAY UNDER THE DANUBE AS WELL

Monday afternoon the north TBM of metro 4 was also able to set off from Szent Gellért square on its way under the Danube towards the Pest side, to where its south pair had arrived exactly a week ago. Prepared for the specific soil conditions under the river the professionals carried along a special instrument brought from Hamburg on the plant, it allows almost instant cleaning of the cutting shield in case clay gets stuck on it.
Tunnel boring machines used for metro 4 are one of the most state-of-the-art plants of the world, they could be continuously adjusted by the professionals to the actual soil conditions, but unexpected events may still occur. Recently it took almost one and a half weeks for the experts of the tunnel building company to clean under caisson pressure the TBM’s cutting shield from the stuck clay. As necessary the instrument used now will be able to reduce the time for this cleaning process to two to three days only.

The south TBM worked for six weeks in total under the Danube, and reached the Pest side on 29th June. Likely its north pair will also need this time to cover the 300 meters stretch under the river. Meanwhile, the maintenance and preparation of the south TBM arrived into the Fővám square station is taking place simultaneously in order to facilitate its departure towards Kálvin square soon, as planned before the north TBM’s arrival to the Pest side.

Budapest, 6th July 2009
DBR Metro Project Directorate