Drive mechanism planning for a lift bridge over the Salzach river (Mittersill, Austria)
The Mittersill lift bridge takes the B165 main road over the river Salzach in the town centre of Mittersill. In the town area of Mittersill, the river Salzach is canalised. The existing bridge projects into the canal outlet width during high water and hence causes a damming up and/or increase in the upstream water level in the event of debris blockage. This immediately results in a flooding risk for the town of Mittersill. For this reason, a lift bridge allowing for flood release was planned. In case of high water, the bridge can be lifted by 1.80 m to ensure free flow in the canal.
The superstructure of the mobile bridge is a welded steel trough structure. The superstructure is supported on elastomer bridge bearings. The abutments are adapted to the bearing conditions of the mobile superstructure. During lifting and lowering, as well as in the open position, the bridge deck is guided and supported separately.
The drive mechanism of the lift bridge in Mittersill is designed as an electro-mechanical unit drive with electric lifting cylinders. The electric lifting cylinders are suspended on pylons. The pylons transfer the lifting forces into the abutments. For locking the bridge in the top position, a locking mechanism with a locking bar has been provided. The locking bar is driven electro-mechanically by electric lifting cylinders.
If there is a flood risk, the bridge can be opened fully within a maximum time of 30 min. In case of a power failure, a backup unit may directly be activated electrically.
Planning was performed in cooperation with the engineering offices Schimetta Consult Ziviltechniker Ges.m.b.H., Leonhardt, Andrä und Partner Beratende Ingenieure VBI AG, and DriveCon GmbH.