Cost-effective demolition of viaducts

Demolition shears as the key equipment

The Langenschwarz Viaduct on the A7 federal motorway near Fulda is being replaced. Wende, the company tasked with taking down the 326-metre-long old structure, will be using powerful and robust excavator attachments.
Wende Erdbau – the name stands for a specialist in earthworks, demolition and the recycling of building materials that is based in Fulda in Hesse, Germany and has been in business since 1947. The company and its 70-strong workforce is currently demolishing the Langenschwarz Viaduct on the A7 federal motorway as its showcase project. The structure was built in 1967 and is now no longer able to cope with today’s traffic loads and so requires replacement by 2021.

The western section of the structure (travelling from Kassel to Würzburg) is being completely demolished, i.e. superstructure and pylons, foundations and abutments, during the first phase of work. Sebastian Wess of Wende, explained the challenges that the company will be facing during the pro-ject: “We need to remove a total of around 20,000 tonnes of reinforced concrete. The crushed and processed concrete has already been firmly incorporated into our operational material-logistics plans. The scheduling is also tight because the new bridge is already being built while the old one is being demolished.”

The bridge is 35 metres high at its highest point, which required that a supporting scaffold be erected especially for the demolition of the super-structure. A 30-tonne excavator equipped with GDT 290 demolition shears that have been supplied by Genesis will be crushing the box girder and then sorting the materials into the steel and concrete fractions. The rebars are being cut using Genesis GXT 225 R scrap shears. A 35-tonne long-front excavator will then start demolishing the bridge pylon that has been exposed after the bridge sections have been removed. The driver will then transfer to a 40-tonne excavator that is equipped with a shorter arm and that delivers more hydraulic power to speed up progress on the last five vertical metres down to the foundation.

“The high art of demolishing a bridge structure,” said Sebastian Wess, who holds a degree in business administration, “is all based on proceeding ratio-nally. We’re breaking new ground with this demolition project and have equipped ourselves specifically to this end.” In addition to the usual atta-chments, such as hammers and grabs, the 30-tonne and the long-front excavators have been fitted with GDT 290 demolition shears (2,940 kilo-grams) by Genesis while the GDT 390 shears (4,170 kilograms) have been installed on the 40-tonne excavator – all supplied by Bischoff Baumaschi-nen GmbH, which is an authorized trader for Genesis. “The equipment pos-sesses a heavy-duty and high-quality while very slim design,” said Sebasti-an Wess. “It allows the wearing parts to be replaced quickly. These shears enable us to make rapid progress while maintaining high operational safety and low wearing costs.“.