SR 520 Floating Bridge

Project description

The Governor Albert D. Rosellini Bridge Evergreen Point (commonly called the SR 520 Floating Bridge) carries State Route 520 across Lake Washington from Seattle to Medina. The SR 520 Bridge Replacement development reached its final construction phase with the West Approach Bridge South Project in 2023.

The new structures feature a floating pontoon bridge across the lake, and two prestressed girder bridges on the western approach. These bridges include wider lanes and shoulders, and accomodate a 14-foot-wide bicycle/pedestrian shared path.

mageba scope

mageba supplied a total of 22 TENSA-MODULAR (type LR and LR-LS) expansion joints for the new bridges, as well as TENSA-GRIP (type RS-B5) strip seal joints. The joints range from 2 to 16 gaps that allows up to 48.4 in (1,230 mm) longitudinal service movement, or 70.4 in (1,790 mm) of extreme limit state movement.

The joints on the approach bridges are equipped with noise-reducing “sinus plates”, which provide a smooth driving surface for vehicles, minimizing vibration and noise by up to 80 %. Another feature is the ROBO-MUTE blanket panels, a system of mat layered membrane that reduces noise transmitted from beneath the joint.


Installation of a 16-gap TENSA-MODULAR LR joint on the SR 520 Floating Bridge in 2016

main floating structure


Installation of a TENSA-MODULAR LR8-LS expansion joint equipped with noise reducing sinus plates in 2017 on the floating bridge’s West Approach


Pouring the concrete into the recess


Car over-rolling on an installed modular expansion joint on the North Structure of the floating bridge’s West Approach Bridge


3D view of the installed modular expansion joint featuring sinus plates and noise protection mats beneath the joint


Lifting of a TENSA®MODULAR expansion joint into position on the new South Structure of the SR520 West Approach Bridge in 2023


Assembly of a 16-gap modular joint in the factory and to be delivered for the main floating structure of the SR520

Key Data


TENSA-MODULAR LR joints (LR2, LR6, LR7,LR8, LR16), TENSA-MODULAR LR-LS joints (LR-LS6, LR-LS7, LR-LS8), TENSA-GRIP RS-B5 strip seal joints


Noise-reducing “sinus plates” on surface, ROBO-MUTE noise protection mats


2015–2016, 2017, 2022–2023


Seattle, WA


Prestressed girder bridges and floating pontoon bridge