BORING MACHINES OF METRO 4 ARE WORKING ON A SECTION WITH FULL OF CHALLENGES

South TBM of metro 4 could be launched towards Rákóczi Square three weeks ahead of schedule, and it now passed the line of the tunnels of metro 3, and its north pair will embark soon as well. The length between Fővám Square and Kálvin Square has been completed with the best pace up to date, and for the twice as long current section the experts plan only eight weeks either. Of course, provided they don’t have to face unexpected difficulties. In any case, it is not going to be an easy section: in addition to the crossing tunnels, diverse ground conditions should be expected, and some old buildings will require special attention, as well.

As know, the tunneling works proceeded slower than planned at the Buda side, but in parallel the stations were built in a good pace. With the completion of the final ceilings, several work sites could be narrowed and partially handed back to the traffic, or handed over for the associated surface projects. Moving of the equipment of the remaining works and the servicing instruments of the boring machines takes place through the so called delivery holes formed on the ceilings at the Pest side.

With reference to the ensued harder accessibility the now STRABAG led BAMCO consortium in its recently submitted works program has planned six weeks instead of the usual three for the maintenance and preparation of the TBMs at most of the Pest side stations. After all, the tunnel builder was able to finish the preparation in a very good pace, as a result of which the south TBM could embark after three weeks instead of the planned six from the Kálvin Square station towards Rákóczi Square last Friday.

The experts of STRABAG and HÍDÉPÍTŐ proved their skills not only in this, since the south TBM completed the 360 m tunnel length between Fővám Square and Kálvin Square within 4 weeks, while its north pair launching two weeks later did it only in 3 weeks. Thus in summary it may be noted that in five weeks more than 700 m of tunnel was completed. The sometimes 18 to 21 m per day working pace is an outstanding achievement not only in domestic metro construction, but it is a performance that deserves recognition internationally also. In addition, the section just finished was not easy, as the ground conditions are more diverse in Pest, than they were in Buda, and the more diverse ground composition requires continuous readjusting of the TBMs, moreover the church building at Kálvin Square that was previously strengthened in its foundation needed special attention, as well.

But the current section will not easier either. In addition to the fact that starting from the station the TBMs should pass over the tunnels of metro 3 only by 1.5 m, the ground conditions between Kálvin Square and Rákóczi Square may be different from the previously usual and respectively special attention is to be paid by the tunnel builders to the buildings of the National Museum and the Hungarian Radio. Here such a monitoring system assists the works of the experts, which not only on the surface, but in the tunnel also continuously, 24/7 monitors the movements of the buildings and the ground.

The south TBM as departed a few days ago has now passed one of the tunnels of metro 3, and soon will reach the other, and its north pair will also follow in a week as per the plans. The section now is nearly twice as long, as the previous one, thus the TBMs may reach the Rákóczi Square station the earliest in eight weeks, i.e. sometime in January 2010.

Budapest, 10th November 2009

DBR Metro Project Directorate