The “power mole” passed the exam

The tunnel boring machine was tested in Germany and handed over officially to Hungarian experts a few months ago. Since the machine is 116 meter long, it will be delivered to Hungary knocked down to pieces and reassembled at the entrance of the tunnel, on the Etele Square. The cutter disc mounted at the front of the TBM was delivered in May.

Performance: 25-30 meters length of new tunnel a day

The tunnels of the new line of the Metro are built by the use of 2 TBMs which have the ability to proceed at a rate of up to 30 meters a day. The first TBM is scheduled to arrive at the end of this month, and the second machine is expected to be delivered in November. Tunnel construction commences in January the latest. Launched from Etele Square the two TBMs are planned to complete in 84 weeks the construction of two tunnels of 7.4 kilometer length each. An interesting detail that the earth excavated will be lifted to the surface from the tunnel boring machines by the use of boxcars. The tunnel components replace immediately the excavated soil to provide instant support; in this manner the possibility of surface subsidence is reduced to minimum. (For a more detailed description of the operation of the TBM visit this link)

No disturbance caused by the TBM on the surface

The operation of TBMs is not perceivable on the surface. Since the boring head makes only one revolution per minute, it will cause no vibrations or rumble. Tunnel construction will proceed day and night, without stopping.

Safe working conditions underground

The tunnel boring machine is almost fully automated; all phases of work are performed under the control of multiple-redundancy computer systems yet under continuous human monitoring. This state-of-the-art equipment responds without delay to any unforeseen conditions such as water inrush, change in the rock/soil conditions, etc. The TBMs have even a fireproof “panic room” inside equipped with oxygen bottles offering safety for the staff under special emergency conditions.

The arrears of work at the Gellért Square can be made up; all in all the project proceeds by the schedule.

The entire Metro Project proceeds as scheduled. The construction of the launching pit for the TBMs is in progress at the Etele Square. The construction of stations at Tétényi Street, Bocskai Street and Móricz Zsigmond Circus also progresses by the schedule. Tunnel construction may commence at the beginning of the next year the latest. Design work progresses in the background at a rapid pace, covering the construction and architectural design of the stations; the preparation of Stage II and the design of the metro wagons is underway; there is only some delay at the Gellért Square.

During the construction of the metro in a crowded metropolis unforeseen events may call for the radical redrafting of primed scenarios no matter how carefully were they prepared. There have always been works that proceed behind the schedule, and some others may be completed earlier than planned. This has been the experience all over the world and Budapest is not likely to be an exception either. For example the overflow shaft of the Gellért Bath was discovered on the Gellért Square during construction works, since this structure did not figure on any of the design drawings. This called for the modification of the design drawings and further delay was introduced at the application for construction licenses. Contrary to the initially planned late Autumn date the Műegyetem Quay will only be reopened for traffic in the spring of 2007. This will not jeopardize, however, the planned completion of the Metro in 2009.

Specifications of the tunnel boring machine

Length: 116 meter. Diameter: 6.05 meter. Nominal average speed: 12-15 meter/day. Energy consumption: 4.1 MW for operation plus 1.7 MW for control/monitoring. Price: approximately € 22 million.