Rehabilitation of a Highway Bridge in Service, Austria

The Brenner Highway runs from Innsbruck, Austria, to the Brenner Pass, connecting northern Europe and Italy. There are a series of so-called "mushroom" bridges with vaulted slabs along the highway; "full" mushroom bridges carry lanes in both directions, while "half" mushroom bridges carry lanes in only the northern direction, with southbound lanes built conventionally on grade. Routine inspections at the end of the 1970s detected insufficiently injected tendon ducts at various locations on the bridges. A large-scale rehabilitation scheme investigated all the mushroom bridges and problematic tendon ducts were post-grouted. The rehabilitation scheme began in 1978 and was completed in 1982. In 1989, work began on another bridge, and the rehabilitation scheme proposed coupling the longitudinal tendons of the structure, thus connecting all mushroom bridges. The basic idea of the rehabilitation was to re-design the bridge as a continuous girder to eliminate vulnerable joints.