“We want to blow up.” The director of the west branch of the state-owned Autobahn GmbH, Ulrich Neuroth, delivered the news of the day in the drama about the Salzbachtal bridge with this surprising announcement. Not only the southern structure of the motorway bridge built in 1963, which is in danger of collapsing, is to be demolished soon by the demolition masters. At the same time or just a few days later, the north bridge should also fall, over whose three lanes 80,000 vehicles were still rolling daily until Friday a week ago.
A year ago blasting was considered too risky, among other things because of the tracks under the bridge, a federal road and the main sewage treatment plant of the state capital. Since the south bridge was lowered in places by up to 50 centimeters on June 18 and moved ten centimeters in the direction of Frankfurt, the risk has been considered acceptable. Because cracks and joints gape in bridge and pillars. The south bridge could collapse at any time, said Matthias Hannappel, the division manager of Autobahn GmbH responsible for construction and maintenance.
The decision to blow up both halves of the bridge was preceded by numerous investigations and discussions. According to Neuroth, the decisive factors were considerations with a view to the security situation, the time required and the costs. In addition, even after a careful demolition of the south bridge with the help of excavators, which probably took nine months, the north bridge could no longer have been put into operation. There was no one who wanted to take responsibility for it, so Hannappel and Neuroth. “We don’t know what happened underground,” said Neuroth.
Completed three years earlier than current planning
Investigating the cause also has to wait because even construction workers and experts are currently restricted to a 25-meter restricted zone around the bridge. First of all, the bridge is to be stabilized “remotely” over the next few days. For this purpose, so-called auxiliary towers are maneuvered next to the now crooked “E pillar” by a special vehicle. The two neighboring pillars also have to be stabilized, among other things by a kind of cushion that takes the load if another bearing collapses. This is to prevent further “uncontrolled movements” of the bridge.
The advantage of blasting is that the railway line to the main train station and the southern entry and exit route “Mainzer Straße” can be opened again in ten weeks. The disadvantage is that the A66 motorway will be completely interrupted until at least autumn 2022. Neuroth spread the hope on Friday that the new construction of the four-lane south bridge, which had already been initiated, could be completed within a year due to the foundation of the new pillars and the prefabrication of steel elements. That would then be a significant improvement in the traffic situation compared to the three-lane, poorly reinforced north bridge. The new construction could possibly begin in parallel or at different times, so that a completely new Salzbachtal bridge, each with two four-lane halves, could be put into operation in 2023. That would be three years earlier than currently planned.
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source https://pledgetimes.com/blasting-the-salzbachtalbrucke-a-traffic-engineering-nightmare/
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