electric-tractors_finne-tunnel

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	Tubbing Production with VOLK Electric Tow Tractors

Herrengosserstedt, 18.02.2008 – One of the most ambi-
tious plans within the framework of the German Reunifi-
cation Traffic Projects established by the German Gov-
ernment in 1991 is the expansion of the high-speed rail connection between Munich and Berlin. After completion of the high-speed railway in 2017, the travel time be-
tween the two cities should be reduced to less than four hours.

One of the main points of the construction work currently lies in the erection of the rail route between Erfurt and Leipzig/Halle. Several large viaducts and three tunnels are located on this 123-kilometer-long route which has been designed for maximum speeds of up to 300 kilo-
meters per hour. With a total length of 6.970 meters the Finne Tunnel will be the longest tunnel on this section
of the rail route. It crosses through the Finne mountain range between Herrengosserstedt (Thuringia) and Bad Bibra (Saxony-Anhalt).




	The construction work at the west portal of the Finne tunnel is already in full progress – starting in May, two gigantic tunnel boring machines will begin digging their way from here through the Finne mountain range

The construction will consist of two parallel single-track tunnel sections, which run with an average distance from one another of 25 meters. The tunnel driving is conducted using the so-called shield driving method. Starting in May, two 3.800 KW strong and 86-meter-long tunnel boring machines with an average driving speed of 16 meters per day will begin eating into the mountain from the west portal. The removal of the 3.000 cubic meters of rubble per day




	Each of the two tunnel sections will consist of a total of 3,400 such tub- bing rings – The seven reinforced concrete elements of a tubbing ring are put together fully automatically by the tunnel boring machines

takes place on special troughed belt conveyors integrat-
ed in the tunnel boring machines.

Just a few meters behind the constantly rotating cutting shield with its carbide teeth, the machine inserts the pre-
fabricated concrete elements of the „tunnel shell“ fully automatically. The tunnel shell is thus completed in a single work step. Each of these prefabricated concrete elements, known in technical terms as tubbing, is about five meters long, two meters wide, 45 centimeters thick and weighs about eleven tons. Together, six tubbings and a smaller end piece form a tubbing ring with an in-
ner diameter of 9.60 meters and a width of two meters. The rings are screwed together and are fitted with rubber seals to prevent water from penetrating.

Upon their completion, both tunnel sections will be com-
prised of about 3.400 tubbing rings each. This is equiva-
lent to more than 488.000 tons of concrete. In light of these colossal dimensions, it is readily apparent that a long-range transport would be associated with enor-

mous costs. The production of the tubbings therefore takes place in a so-called field factory directly at the construc-
tion site. In direct proximity to the west portal, a production hall with an area of about 5.600 square meters was built. Since the end of January, special concrete is already being cast in steel molds in order to manufacture the neces-
sary components for the tunnel construction. This lead time is required, since the tubbings must first be stored for

28 days after production in order to harden completely. This also guarantees that the tubbing production will always be able to keep pace with the speed of the two tunnel driving machines during the entire construction phase.

The production process of the tubbings is divided into several steps, beginning with the manufacture of the steel reinforcements and moving on to the installation of the reinforcement cages in the casings, the filling of the casings with fresh concrete, the removal of the casings, the pressing in of the seals along the outer contours of the tubbings, and finally the end inspection and subse-
quent transport of the finished concrete elements to a large storage area outside.

For the transport of the approximately 12-ton concrete charging buckets from the outside concrete mixing plant to one of the 56 casing molds inside the factory, two VOLK Electric Tow Tractors of the type EFZ 20 K with a maximum towing capacity of 20.000 kg and four indus-




	VOLK Electric Tow Tractor EFZ 20 K with a tubbing casing in tow – The steel molds are precision tools which were manufactured especially for the construction of the Finne tunnel

trial trailers with a payload of 15.000 kg each are used. For the transport of the reinforcement cages, four additional VOLK Industrial Trailers with a payload of 2.500 kg each are used. To facilitate maneuvering in tight spaces, the all-
wheel driven trailers feature two drawbars. The trailers can thus be coupled on both sides and need not be turned around in the narrow working aisles of the field factory. Instead the versatile tow tractors just drive around the trailers




	VOLK Electric Tow Tractor EFZ 20 K with a concrete charging bucket – Until the Finne tunnel is completed, a total of 488.000 tons of fresh con- crete must be transported in this way from the mixing plant to the casing station

and hitch to the opposing end.

There were several decisive factors in the selection of VOLK as a supplier: Next to the especially compact di-
mensions of the model EFZ 20 K which are unique in this performance class, the recognized high quality and reliability of VOLK towing machines were convincing overall.

After all, each of the two tow tractors will have had to transport no less than 240 million kg of concrete by the time the tunnel is completed in 2011. Unplanned down-
times and resulting construction delays could quickly lead to extremely high consequential costs in the 250 million Euro project. Another point in VOLK's favor was the fact that the company could offer both tow tractors and industrial trailers from one source.

Since the tubbing production plant will no longer be needed after completion of the tunnel, the further use of all components was already considered in the planning and design phase. The entire plant can therefore be dis-

mantled and rebuilt at another site to produce prefabricated concrete elements for the next tunnel construction pro-
ject. The VOLK tow tractors and trailers will be part of the team again, ready to take on the next 100 million kg of trans-
ported loads.

	The field factory for the manufacture of the tubbings has a production area of 5.600 square meters – In two-shift operation, 112 tubbings are manufac- tured per day

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