Max Wild disassembles bridge at the A 99 by Munich
Highway removal gives extensive demolition order
On account of the steadily growing traffic amount the A 99 should be developed between the motorway junction Munich North and Munich East in six lane. The transport and civil engineering company Max Wild from Berkheim was contracted with the demolition of the existing buildings.
With a demolition volume of from approximately three to four millions euros the demolition works split themselves in several sections. The mega project encloses the demolition of a total of nine buildings.
In December, 2017 it was the task to demolish the centre area of the highway bridge at Ismaning at the ‘Muenchener Strasse’. The three-span bridge constrcution made of pre-stressed concrete has a total of one mass of 9,000 t. The demolition divides itself into two sections. In the first segment the superstructure of the centre area of the bridge built nearly 60 years ago was demolished at the beginning of December, 2017.
A special challenge were up to 95 year-old drainage lines which run approximately 1. 50 m deep in the earth under the bridge. These and other special basic conditions entailed that already in June, 2017 numerous preparatory measures were taken within the scope of a detailed project planning.
Before the real demolition a lot of things have to be done. All vehicles of the city of Munich were redirected in the eastern edge districts over the ‘Freisinger Landstrasse’. Construction site manager Stefan Scholz of Max Wild predicted: ‘By the redirection traffic jams are not to be excluded, and on the redirecting distances quite thick traffic will be.’
After the asphalt cover of the A 99 had been demolished, the first job of the demolition team consisted of, building a 1-m catch ditch from gravel and sand below the bridge. Construction site manager Scholz explains: „The catch dith is elementary, because it damps not only the vibrations if the concrete masses fall down, it also protects the available high-pressure water pipes as well as the asphalt of the street running under the A 99 against damages by our heavy construction machines. “
On and under the bridge a well-functioning team was meanwhile busy with further preparations to the big moment. The reinforced-concrete superstructure was hung up at six HEB 1000 steel beams with thread rods. To prevent that the demolition parts which weighed partly more than 1 tonne fall on the subsoil and on the existing high-pressure water pipes, the superstructure was supported, in addition, by means of scaffolding towers.
Construction site manager Scholz speaks of a demanding demolition, in particular on account of the cramped place conditions. A bridge of this height requires much technical know-how and many years’ experience in the bridge demolition.
After all preparations were made, started the excavator fleet, equipped with demolition sheers, grabs and hydraulic hammers the demolition of the bridge construction. By using hydraulic hammers the superstructure was first perforated and afterwards with hydraulic sheers according to schedule dismantled.
The demolition ran trouble-free, schedule-according and without incidents. A clear relief within the team was to be felt.
In the last step landed 750 m ³ reinforced-concrete on the loading area of the dumper which started moving in the early morning to the nearby storage place to the cracking of the construction materials. On site the reinforced-concrete was pulverised. Finally, everything should be supplied as far as possible to a re-use.
During the next four weeks edge fields, pillar discs and abutments were dismantled. Besides, particularly the dismantling of stripe footings in close distance to the high-pressure water pipes showed a special challenge.
The construction field could be released by the teamwork of all partners, in particular to the skilful teamwork of the machinists and four excavators, faster than planned in view of the traffic.
Max Wild GmbH
Leutkircher Str. 22
Press contact: Lara Zitzer
Tel.: +49 8395 920-640
Fax: +49 8395 920-88645