INTERVIEW WITH GUSZTÁV KLADOS, OPERATIVE PROJECT MANAGER

The National Transport Authority suspended the tunnel construction of the 4th line of the metro; the TBMs will stop for approximately two months. No problem-free continuation is expected either; the TBMs will have to stop again under the riverbed of the Danube for two to four months because of the delay of the construction of the Fővám Square station. The excess cost may exceed HUF one billion.

Interview by Index.hu
By the information of Index the TBMs have been stalling at Gellért Square since one week. What has happened?
Indeed, the Mining Authority under the National Transport Authority suspended the works last Thursday. No license was granted for the construction of a crossover tunnel, which houses the switch used to tow the train from one tunnel to the other. The Contractor, BAMCO, immediately applied for a temporary approval to carry on the implementation of the main running line tunnel until the license is granted for the crossover tunnel. At last, on Wednesday a decision was made on the rejection of the temporary license for the Contractor.
How does it come that there was no license? It should have been granted years ago together with the other licenses?
BAMCO was not aware of the need to apply for a license for the construction of the crossover tunnel, but the licensing authority agreed with our position and ruled a need for the license.
When will the license be granted, and when can the TBM be restarted?
As far as my information goes, the Contractor submitted the required application, and the authority has 60 days to grant approval.
How long will then be the delay of tunnel construction and the construction of the Gellért Square station?
Tunnel construction will be delayed two months at most, as I said. The setback of station construction will not exceed six months.
So the metro will not be completed by 2011?
The delay of the Gellért Square station will not necessarily affect compliance with the completion deadline. We can catch up with the delays so that we carry on with works that otherwise were scheduled to be completed later.
Why have you not proceeded in this manner so far?
There are many phases of works dependent on tunnel construction; these could now be rescheduled because of the stand-down of the TBM.
The TBMs are restarted say in two months time. When will they reach the Fővám Square station?
If everything is taken into account, they will get there perhaps in January 2009.
The construction of the Fővám Square station, however, is also delayed. Will it be ready by that time?
By an optimistic forecast the Fővám Square state will be completed to the condition ready to receive the TBMs next March; in the worst case this will take place in May.
It means that the TBMs will have to be stopped for two to four months again, and now they will be halted under the riverbed of the Danube. What will be the cost of this stand-down, and who will carry these costs?
Yes, a 60 to 120 day stalling under the riverbed of the Danube is forecasted, and the Contractor will obviously submit a claim for the reimbursement of its expenses including the costs of machine downtime. I cannot predict the figure, but I do know that the Contractor was paid the equivalent of HUF 5 to 6 million for each and every day of downtime in Malaysia, where I worked on a similar tunnel construction project not long ago.
If we take this figure as a basis, the reimbursement of excess costs payable after the two TBMs may exceed HUF one billion.
I do not wish to guess. We shall make an offer, and the Contractor will do the same, then we shall try to come to an agreement.
Earlier the option to pass the TBM under the Fővám Square emerged instead of shutting it down, so that the more risky platform tunnels are built later. In this manner there would be no delay and no excess costs for downtime would incur either.
Had we decided to pass the risky stage and built it later when the tunnel is ready say until the Kálvin Square, then who would have taken responsibility for an accident, perhaps a water inrush? Then water would inundate the tunnels with TBMs and staff! Moreover, even the 3rd line of the metro would have been jeopardized through the Kálvin Square underpass. No matter how little is the probability of this to happen, it is still better if such accidents occur before the tunnel construction.
So what will happen then to the Fővám Square station? Nearly one year go on the discussions on the method of construction of the platform tunnel of the station protruding under the riverbed of Danube.
No decision has been made yet. The contractor of the station, Hídépítő, Inc. suggests the freezing method. The essence of this method is that the soil around the future tunnel is frozen by the use of liquid nitrogen to prevent the eventual water inrush. This technology, however, is expensive and slow. In my view the so-called tube umbrella technology is more adequate. In fact, it coincides with the first phase of the freezing process. Horizontal tubes supporting soil during the tunnel boring are drawn in above the future tunnel. In the case of an eventual water inrush could the second phase, i.e. freezing be applied, but it is highly unlikely based on the soil samples available. Freezing would make construction excessively costly; the tube umbrella solution costs a fraction of the former at nearly the same level of safety.
Gábor Tenczer, Index.hu