A partner for life

Modifications to design standards and ever-changing usage patterns can lead to evolving demands on historic structures. s your structure equipped with mageba bridge bearings or expansion joints? You can rely on our expert team to remain on hand should needs of the asset change throughout the service life – as was recently the case with the SR520 pontoon bridge in Seattle.

A bridge expansion joint is not like a TV or a sofa, to be simply disposed of and replaced when it no longer meets the owner’s requirements. When a complex device such as a TENSA®MODULAR expansion joint requires to be upgraded or modified, the solution should minimize impacts on the structure and on traffic – for the sake of the structure’s users, the environment and the owner’s finances. But upgrading or modifying such devices requires expertise and commitment from a supplier that has been an industry leader for decades already and can therefore be relied on to be there in the future when the need arises.

As reported in our previous newsletter article “Sleep well in Seattle”, mageba has been the expansion joint supply partner in the decade-long project to construct Washington State’s Evergreen Point Floating Bridge (also known as the SR520 Bridge) and its approach structures. This started with the supply of the very large TENSA®MODULAR expansion joints required for the main structure, which opened in 2016 as the world’s longest floating bridge. In the years that followed, mageba went on to supply noise-reduced TENSA®MODULAR expansion joints for the North Structure of the floating bridge’s West Approach Bridge, complete with ROBO®MUTE noise protection beneath each joint. And now the South Structure of the West Approach Bridge has also been constructed, again featuring noise-reduced TENSA®MODULAR expansion joints.

If ever these high-performance devices require to be renovated, mageba will be able to offer optimal solutions, such as the “box-in-box” renewal method which largely avoids breaking out and replacing the parts of the joint that are concreted in place. But even before that time comes, a need may arise to modify expansion joints for other reasons – such as the change of structure use necessitated by the opening of the South Structure and the resulting change of traffic flow on the older North Structure. This requires the traffic barrier between the eastbound and westbound lanes on the North Structure to be moved approximately 8 ft, or 2.5m, towards the center of the superstructure at one end. Since the 7-gap expansion joints at that end are discontinuous under the traffic barrier, the expansion joint discontinuity would be in the wrong place going forward.

Fortunately, mageba was able to propose and implement a solution that avoids completely replacing the two expansion joints, adapting the existing joints to suit the new barrier location. This complex solution required ingenuity and great skill – and also, of course, a partner that has been there for the client from the start and will always be there to provide support like this in the future. A partner like mageba. 

Owner: Washington State Department of Transportation
Contractor: Graham

When Seattle’s Evergreen Point Floating Bridge (SR520 Bridge) opened in 2016, it was the world’s longest floating bridge and featured large TENSA®MODULAR expansion joints at each end

The connecting West Approach Bridge was also constructed with TENSA®MODULAR expansion joints, with noise-reducing surfacing – first its North Structure, and now also its South Structure

With the South Structure of the West Approach Bridge ready to be opened, the traffic flow on the North Structure required to be adapted – with the traffic barrier at its center moved, impacting on the lengths of the expansion joints

In order to move the traffic barrier, and thus also the discontinuity in the expansion joints on this bridge axis, a short section of expansion joint had to be removed and replaced

Removing and replacing a short section of modular expansion joint is a complex process involving the adaptation of all components – including the support bars that span the bridge movement gap and provide sliding support to the surface beams above

Three new support bars (covered here for protection) were required to support the surface beams of this short new section of expansion joint

The elastic movement control system, which distributes the overall bridge movements among the joint’s individual gaps, also required to be connected to each superstructure

Welding of upturns to the ends of the existing surface beams where they were cut to suit the new location of the traffic barrier