STAHL CraneSystems GmbH

05.07.2010

The idea of using portal cranes for construction work is not new. But on a bridge – not just any bridge, but a bridge with a slight curve, an incline and low load capacity! That was a challenge not just for Hungarian crane manufacturer GD: this is the first time that this crane technology has been used on a bridge in Hungary at all.

The Margaret Bridge is one of the 9 bridges over the Danube in Budapest in Hungary: built in 1876, destroyed in the Second World War, reopened in 1948 and fully restored for the last time in the Seventies. The general renovation of the busy bridge had been overdue for many years and was begun last year.

The bridge has been closed to motor traffic since 21 August 2009. A particular requirement was that the Margaret Bridge must remain passable for trams and buses during the whole construction period which makes it practically impossible to transport building materials to the construction site by lorry. Thus the unusual plan was devised to build two off-standard portal cranes.

As the lorries cannot park on the bridge or at the bridgeheads they deliver the components via the dock which runs along the riverbank below the bridge. From here the cranes lift the steel and concrete sections which are 13-14 m in length onto the bridge by means of a 5 m long overhang beam and transport them into the correct position without rotating them. To permit this, the dimension between the portals was increased to 18 m on  the overhang beam side – a specially reinforced cross beam in a welded latticework ensures the necessary stability in spite of the wide spacing. A further advantage is that the area at the edge of the bridge is more easily accessible so that it is easier to mount the components for the new pedestrian and cycle path.
 
Each portal crane can completely cover one half of the bridge on its 320 long crane runway. One of the biggest challenges for GD's crane designers was distributing the load so that the bridge can withstand the stresses. A further difficulty was that the north and south sides of the bridge have a 1° bend and an incline of up to 3% so that conventional portal crane undercarriages were excluded from the outset. The remedy was found in four specially manufactured undercarriages from the German crane technology specialist STAHL CraneSystems. Each of these units consists of four driven wheels which can swivel both in pairs and jointly. Thus a maximum wheel load of less than 5 tonnes is achieved which is lower than the wheel load of the Budapest trams. The total output of the 16 driven wheels is 35 kW so that the cranes  can operate safely even with 16 t rated load, 3% incline and a wind speed of 50 km/h. Two robust wire rope hoists from STAHL CraneSystems' SH series are used as lifting apparatus, the cranes are radio-controlled.

The 130 employees of Hungarian crane manufacturer GD cover all functions from design to crane manufacture to erection. The company is regarded as STAHL CraneSystems' most important partner on the Hungarian market. As a manufacturer of off-standard cranes and transport solutions, the traditional Hungarian company has trusted in the competent advice of STAHL CraneSystems' high-performing R&D department for many years.

GD erected the portal cranes in December 2009. They have been in daily use since then: they lift the heavy reinforced concrete elements from the carriageway and transport them to the loading point at the bridgehead. Later they take up the new carriageway sections there and manoeuvre them into the correct position. The construction work is being carried out by a consortium of companies comprising Közgép, Strabag and Hídépítő under the direction of Közgép. Completion is scheduled for the end of 2010.


Photo material:

	Picture 1: Unusual design: off-standard portal crane with 5 m overhang beam, 18 m spacing between portals and 15 m height of lift.
	Picture 2: The Margaret Bridge will remain open to trams and buses for the duration of the construction work. In the background: the Hungarian Houses of Parliament.
	Picture 3: The Margaret Bridge is one of the busiest bridges over the Danube in Budapest. It was built in 1876, is 637 m long and 16 m wide.
	Picture 4: View from the middle of the bridge onto Margaret Island: each of the two portal cranes can travel over half the bridge on a 320 m long crane runway.
	Picture 5: The Margaret Bridge will remain open to trams and buses for the duration of the construction work.
	Picture 6: The best choice for outdoor applications too: the robust, low-maintenance wire rope hoists from STAHL CraneSystems. During general renovation the old carriageway elements will be replaced by a new carriageway system.
	Picture 7: The best choice for outdoor applications too: the robust, low-maintenance wire rope hoists from STAHL CraneSystems. During general renovation the old carriageway elements will be replaced by a new carriageway system.