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As an interim solution, the “Pack” section of Austria’s A2 autobahn, in the southern province of Carinthia, was built as a single-carriageway motorway in the 1980s. Work is now in progress to upgrade this section to two full carriageways, necessitating the building of nine new bridges. By far the most spectacular of these is the 935 m long “Lavant Viaduct”. Its eight piers are rising swiftly and safely with the Guided Climbing Formwork GCS from Doka.
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The building of the first, 1079 m long, bridge across the Lavant valley in western Carinthia in 1986 attracted huge media interest. After all, its height of 164.0 m makes it the second-highest bridge structure in Austria, after the “Europabrücke” near Innsbruck. It shares this distinction with the new project, which is being built by the same construction company, Steiner-Bau GmbH of St. Paul im Lavanttal. The new bridge is going up right next to the first structure, which it strongly resembles. The carriageway deck rests on a total of eight piers, four of which are designed as double piers. The individual hollow piers, with footprints of 3.0 x 9.0 m and wall thicknesses of 40 cm, rise to heights of as much as 136 m.
The twin-carriageway upgrade is scheduled for completion by 2007 – and anyone seeing how fast the new bridge piers are progressing thanks to the Doka climbing formwork GCS can be in no doubt about this particular deadline being met!
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Since Bauma 2004, the internationally field-proven Doka systems Climbing formwork MF 240, Automatic climbing formwork SKE and the Platform SCP have been joined by a newly developed system called GCS. This is a firmly structure-guided formwork system that remains anchored to the structure at all times, even while being lifted. In this way, lifting operations can be carried out very safely even in high winds, and with only one crane cycle, which makes them very fast and economical. Another advantage: There is no need to clear away tools and constantly needed small items – these can simply be left on the platform when it is lifted.
The functional sequence is at once logical and simple: The entire unit to be lifted – consisting of the climbing scaffold, working platforms and formwork element – is guided up the side of the wall, in profile rails fixed in prepared suspension shoes.
Once this climbing unit (for the outside formwork) has been crane-lifted to its next working position, gravity pawls automatically anchor it in the suspension shoes for the next section. It only takes one or two persons, plus the crane operator, to carry out this repositioning operation.
The inside formwork stands on a shaft platform with gravity pawls which also automatically latch into place when the unit is crane-lifted (at the end of each lifting cycle), thereby providing a safe support for the shaft platform (in the prepared recesses).
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The piers of the new bridge are thrusting upwards from the valley floor in 4.50 m high casting sections. One set of formwork is in use for each double pier. The climbing system GCS is fitted out with elements of the tried-and-tested Doka large-area formwork system Top 50, supplied to the site tailor-made for the 98 usage cycles. The planning target for the four double piers can be summed up as “One casting section a day”, with pouring taking place alternately on the left-hand and right-hand pier shafts. In the space of only two-and-a-half to three days, an entire section of the double pier is formed and poured, and the GCS climbing formwork raised to its next position.
The two tallest double piers, one measuring 126.64 m and the other 136.36 m, are each being given two 4.5 m high transverse stiffeners. These are cast jointly with the pier shafts in one single pour. The formwork needed for this is mounted and supported on special brackets and an IPB-section steel girder.
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The twin-carriageway upgrade of this 9.3 km long section of “cut-price provisional motorway” will be completed by the autumn of 2007. For Carinthia, says Provincial Governor Dr. Jörg Haider, this is “...a top-priority project that optimises a vital intra-Austrian transport link while also enhancing road safety...”. After the addition of a second tunnel tube, the renovated Gräbern Tunnel was opened to traffic back in June 2004. Existing tunnels have been rehabilitated and refitted in line with the latest “RVS” road-building guidelines from the Austrian Transport Ministry.
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| The bridge superstructure is being constructed as balanced cantilevers, also using Doka formwork systems. |
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The first bridge of the Lavant valley crossing was opened in summer 1986. Originally built as an “economy grade” bridge with 2 lanes in each direction, this first bridge is now being supplemented by a second one as part of the twin-carriageway upgrade of Austria’s A2 Vienna-to-Italy autobahn. Particularly during the busy holiday travel season, this will relieve the pressure on the “Pack” section of the A2, and enhance road safety.
Using Doka formwork systems, work on the piers and superstructure of the new bridge is moving swiftly ahead.
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| The higher four of the eight double piers for the second bridge of the Lavant valley crossing are being constructed using the Guided Climbing System GCS from Doka. |
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