No structural bearing replacement challenge we can’t handle

mageba’s team in Germany demonstrates its expertise in replacing the old roller bearings of a railway bridge with the superior modern alternative, the RESTON®CYLINDER bearing – and completing the job on schedule despite the substantial challenges encountered.

When it comes to bearing supply and installation projects, the most demanding tend to be bearing replacement projects in existing railway bridges – and none are more challenging than those of DB Netz AG, Germany’s railway network company, considering the high train speeds and traffic volumes arising and the company’s extremely high standards relating to quality, operational safety and schedule reliability.

Happily, mageba’s team in Germany has in the past shown what it can do on German railway projects that required tailored bearing replacement solutions and detailed planning, such as the Hochheim Railway Bridge over the River Main and the Fehmarn Sound Bridge over a part of the Baltic Sea.

So when it became necessary to replace old roller-type bearings of the railway company’s “Y-Bridge” near Bischofsheim in southwest Germany, the client could have confidence that mageba would meet its expectations – in spite of the very tight window of opportunity for carrying out the work on site.

In a previous newsletter article, we described how the RESTON®CYLINDER bearing is the far superior modern alternative to the rocker bearings and roller bearings of the past. It offers much better long-term performance due to the way it facilitates rotation about a longitudinal axis by means of sliding rather than rocking or rolling – thus avoiding the extremely high pressures that can arise when all the weight supported by a bearing is transmitted across a contact surface that consists of a line rather than a two-dimensional area. The RESTON®CYLINDER bearing also offers the advantage that it can be designed to accommodate rotations about its transverse axis as well as its longitudinal axis (the “DUPLO” design as opposed to the simpler “MONO” version). And its rectangular shape on plan (relatively long and narrow) makes it ideal for replacing old rocker bearings and roller bearings – two bearing types that share this geometrical feature.

Having been awarded the contract to carry out the work in the role of General Contractor, mageba had responsibility for every aspect of this multifaceted and complex project – including, for example:

  • Design and fabrication of the new bearings to replace the existing ones (considering all dimensions and connection possibilities as well as loads and movements, etc.)

  • Preliminary work in the form of specimens and samples for the testing required to obtain the necessary internal company approval (UiG) and individual approval (ZiE) from DB Netz AG

  • Obtaining approvals, involving full-scale testing of specimens, for various connection details to existing structures

  • Clearance of the site and provision of access to the Y-shaped piers

  • Provision of access by means of scaffolding to the bearing locations

  • Implementation of concrete adaptation works on the bridge’s existing substructures

  • Implementation of the temporary steel frames (including concrete foundations) required to support hydraulic lifting equipment

  • Agreement of road and railway track closures and safety measures, in close consultation with all responsible authorities and operators

  • Implementation of traffic management measures

  • Lifting of the superstructure and removal of the existing bearings

  • Installation of the new bearings including any required structural adaptation works and all necessary drilling/anchoring/welding and gap-filling work

One of the greatest challenges, however, was the project’s tight programme, which required the entire design, planning and approval process to be expedited and completed in a very short timeframe. With the work on site commencing in late November 2022, the four bearings of the superstructure in question required to be fully replaced by 31.12.2022, with the removal of the existing bearings only possible during track closures that commenced on 26.12.2022 – six days in which the actual removal and installation had to be carried out.

Thanks to the tremendous efforts and great expertise of our team in Germany, and the excellent spirit of collaboration among all those involved in the project including the client and all relevant authorities, the work could be finished on schedule – demonstrating once again that there is no bearing replacement project we can’t handle!

Contractor: DB Netz AG
Owner: DB Netz AG

The “Y-Bridge”, located near Bischofsheim in southwest Germany, carries an important Deutsche Bahn railway line on twin superstructures across a federal road and another railway line

Roller bearings, often used in the past before the invention of superior alternatives, are subjected to very high loads at the “linear” contact surfaces between the cylinder and the flat plates above and below

Illustration (exploded view) of a RESTON®CYLINDER bearing of the MONO type, which accommodates rotation about its longitudinal axis only (and can be designed to accommodate or resist horizontal movements)

Like the MONO type, the RESTON®CYLINDER bearing of the DUPLO type facilitates rotations about the structure’s transverse axis – but thanks to the curvature of the upper sliding surface, the DUPLO type can also accommodate rotations about the structure’s longitudinal axis. In case of relevant rotations about the vertical axis, the DUPLO type can be equipped with a third, flat sliding surface

Design representation of one RESTON®CYLINDER bearing of the DUPLO type, as designed for the Y-Bridge (carrying vertical load of 2467 kN, allowing longitudinal movements of +/- 60 mm, resisting transverse forces of 1000 kN) – with anchor bolts connecting to the concrete substructure

Construction of foundations for the steel structures on which the hydraulic equipment for lifting the bridge’s superstructure can be temporarily installed in order to replace the bearings

Lifting of the superstructure using hydraulic jacks to enable the existing roller bearings to be replaced

A RESTON®CYLINDER bearing as installed to replace an existing roller bearing on the Y-shaped pier of the first superstructure