If the viaduct was restored with standard state-of-the-art methods, the expenditure and costs would be enormous and the monument character would be endangered. Fortunately, the Karlsruher Insitut für Technologie (KIT) Innovation Hub "Prevention in Construction" has succeeded in developing a customized approach to sustainable repair of the viaduct.
"Construction of the Laufenmühle viaduct 100 years ago was a technical masterpiece of civil engineers. Now, engineers also break new ground in the restoration of the damaged concrete pillars and arches," explained professor Andreas Gerdes, scientific director of the KIT Innovation Hub.
Based on today's regulations and building data collected, a support construction of 30- to 50-cm thick concrete arches had been envisaged underneath the viaduct. However, this would have changed the appearance of the bridge.
"The associated expenditure and costs would have been enormous," Gerdes pointed out. "Instead, we used modern scientific methods to improve the database and to adapt the repair concept to the viaduct without damaging its basic structure." The use of modern scientific methods for historic constructions results in customized options for the preservation of monuments, in particular for early reinforced concrete constructions.
"By ultrasonic and building radar measurements, every centimeter of the viaduct was examined down to a depth of 50 to 70 cm and documented. The damaged points were identified and assessed," said Gerdes. Cooperation between IONYS AG, a spinoff of KIT, and the Patitz engineering office produced a detailed picture of the damage of the viaduct.
Based on these data, the Rothenhöfer engineering office provided the static basis for repair.
For the Laufenmühle viaduct, cement suspensions will be injected specifically into the damaged areas of the arched bridge. "In this way, the original appearance of the Laufenmühle viaduct will be preserved," Gerdes explained. "And, in addition, restoration costs are reduced considerably."
Now, the city of Welzheim only has to afford an amount of EUR 2.2 million (USD $2.4 million) instead of EUR 3.5 million (USD $3.8 million) for the originally planned restoration. At the same time, further the railway line can continue to operate as a tourist attraction.
Parallel to operation, restoration is planned to be completed by summer 2017.
For more news on infrastructure repair, check out this new method of rapid rail bridge replacement.