Replacement of 55-year-old mageba bridge bearings

mageba is currently replacing bridge bearings that the company supplied for a Swiss highway viaduct in 1969 – marking the end of an excellent service life for bearings of that time.

When the Flamatt Viaduct (Viaduc de Flamatt) was constructed in the 1960s to carry Switzerland’s A12 autobahn across a valley near the capital city, Berne, the bearings were supplied by a local manufacturer that was still in its infancy – mageba had only been in business for six years at the time it designed and manufactured the bearings, having been founded in 1963.

The viaduct is a 13-span structure, and mageba supplied twelve roller bearings to accommodate the new bridge’s movements and uniaxial rotations. These guided bearings were found to require replacement. Rather than replacing them with similar roller bearings, mageba recommended the use of the company’s current alternative – the RESTON®LINEAR bearing, which has a far higher radius at the curved rotation surface to reduce the pressure arising and which facilitates longitudinal deck movements by sliding at a dedicated sliding interface rather than by rolling.

To avoid heavy civil engineering works, mageba’s team proposed to retain the existing upper and lower bearing plates – a decision that then necessitated some ingenuity to make the design work, with the new bearings installed “upside down” to better suit the geometry of the connecting steel.

Having designed and fabricated the new bearings, mageba’s local installation team set about carrying out the replacement works on site, including lifting the viaduct superstructure at each axis using hydraulic jacks, and injection of a special void-filling compound following installation in order to ensure even transmission of forces.

Replacement of the bearings has now been almost completed, marking the end of the 55-year service life of the old bearings – not a bad achievement for what was at the time of supply a six-year-old bearing manufacturer!

Client’s engineer: GVH Tramelan SA
Owner: Federal Road Office (FEDRO)
Installer: mageba

The Flamatt Viaduct is a 13-span structure that carries Switzerland’s A12 autobahn across a valley near the capital city, Berne

When it was constructed in the 1960s, the viaduct’s superstructure was supported by twelve mageba roller bearings at six axes – which served a service life of 55 years before it became necessary to replace them

When the need to replace the viaduct’s twelve guided bearings was identified, mageba’s modern alternative to the roller bearing – the RESTON®LINEAR bearing – was selected for use

Lifting of the superstructure, using a set of six hydraulic jacks, to enable the existing roller bearing to be replaced

The upper and lower bearing plates of each existing roller bearing were retained to facilitate the change of design and to minimise impacts on the main structure

A new RESTON®LINEAR bearing as manufactured to suit the bridge’s movement requirements and the geometry of the connecting structures – showing its “upside down” design and sliding surface protection

Placing of a new RESTON®LINEAR bearing in position with the bridge superstructure still raised by the set of hydraulic jacks

A new RESTON®LINEAR bearing as installed, showing the movement scale that enables the bearing’s movements to be easily monitored

After positioning of each bearing, the voids between the bearing and the substructure / superstructure were injected using a special compound to ensure even transmission of forces