Replacement construction of overpass, BAB A99

The A 99, Munich’s motorway ring, is being expanded to 8 lanes between the AK Munich North and the AS Haar. Construction section II includes the 8-lane expansion between the Aschheim/Ismaning and Kirchheim junctions.
As part of the expansion, the existing overpass BW 33/1 is to be demolished and rebuilt. To maintain a continuous pedestrian and cycle path connection during construction, a temporary bridge must be built over the A 99.

Demolition of the existing structure
The existing superstructure is a 4-field girder prestressed in longitudinal and transverse directions with a two-web plate girder cross-section. Since traffic on the underlying highway had to be maintained on one side (in 4+0 traffic routing) during dismantling, the superstructure was initially dismantled on one side.In the dismantled state, an inner field with a span of 38.32 m became the end field of the system.To ensure load-bearing capacity, auxiliary supports were arranged outside the traffic area. For the load-bearing capacity of the partial superstructure above the traffic, an effective end anchorage of the longitudinal tendons was required at the dismantling section joint.

Replacement construction
To keep the clearance gauge of the highway clear, the replacement structure was raised by 1.15 m on a falsework. In the raised position of the superstructure, the longitudinal restraint and the unconstrained deformability of the superstructure (due to temperature deformations) had to be ensured. After the superstructure was stripped, it was lowered using hydraulic presses via corresponding press and set-down stacks.

Temporary bridge
To maintain the pedestrian and cycle path, a temporary bridge was erected for the construction period. This was designed as a system bridge (Waagner-Biro / Bailley bridge system). The temporary bridge was assembled successively behind an abutment. The manufactured section of the temporary bridge was pushed in over running traffic via corresponding roller constructions in an elevated position over a free span of maximum 54.80 m and then lowered into the planned position.

Noise barrier
The noise barrier, which was also partially dismantled in the course of dismantling the existing structure, was rebuilt. The noise barrier was founded using driven tube foundations. The maximum height of the noise barrier is approx. 6.20 m.