TUNNEL BORING MACHINES (TBM) AT HALF WAY: TUNNELING WORKS IN BUDA COMPLETED

The south TBM also “broke into” the future Szent Gellért Square station of metro 4 on Monday afternoon, 16th March 2009, to where its north pair already arrived at the middle of January. By this half of the first 7.5 km section of tunnels is completed. Arrival of the TBM means the end of the Buda side tunneling works, too.
With the north TBM the BAMCO consortium in hand with the authority's consent had already started building works to the remaining tunnel stretch at Buda side at the beginning of January and by the middle of the month reached the platform tunnel linking to the Szent Gellért Square station. The south TBM could be launched following this only, but prior to its arrival the Contractor still had to finish the internal walls of the concerned station part.

Now TBMs have arrived into the platform tunnels stretching under the University of Technology. Once all the internal walls of the station and platform tunnels are completed, TBMs will “push” themselves into the station from here. As part of the Szent Gellért station a so called connecting tunnel with a diameter greater than the line tunnels will also be built, and it will allow trains to be able to go over from one tunnel to the other. TBMs have passed this area too; the connecting tunnel will be completed by over-demolition once TMBs are gone.

During tunneling works under the river Danube the servicing of TBMs will be continuously relocated from Etele Square to here, to Szent Gellért Square. This means that the delivery of the so called tubbings, which comprise the walls of tunnels, to the TBMs, and respectively haulage of muck to the surface will be carried out from this new “base”, in other words the service center for the Pest side construction will completely move to the Szent Gellért Square work site within a few months. Transportation of muck – with 3 to 4 trucks per hour – will be carried out on the quay way up to Lágymányosi Bridge, and from there further to the three official dumping site used previously also.

Following a few weeks maintenance period usual at these times, the first TBM may proceed to under the Danube sometimes in April and once it reached the Pest side, the other one may also start its way of 4 to 6 weeks. Construction of the Fővám Square station speeded up significantly in last months, thus it will likely be able to receive the TBMs arriving to the Pest side with no trouble.

Otherwise, implementation of all 10 stations shows an advanced state, and the overall project is at about 40% completion, which is well indicated by the numbers. Up to now with the TBM methodology a total stretch of 6,218 m of tunnel has been completed (north and south parts together, added with the lengths of stations and mined structures), into which 24,870 tubbings, 3.5 tons each, were built in by the experts. The two TMBs together excavated nearly 250,000 m3 of muck and worked approximately 15,000 working hours in total.

Budapest, 16th March 2009

DBR Metro Project Directorate