PROJECT SR 99

SR 99

For the landmark SR 99 Tunnel project in Seattle, we provided specialized engineering solutions for what was once the largest diameter bored tunnel in the world. Working with Seattle Tunnel Partners, we delivered custom formwork and hydraulic travelers for critical cast in situ structures, including ventilation shafts and emergency cross passages. Our modular VARIOKIT systems ensured seamless integration with the TBM segmental lining while optimizing labor and crane time in a high pressure urban environment. By providing robust and reusable steel formwork, we helped deliver a seismic resistant highway that has transformed the city waterfront and set new standards for infrastructure resilience.

 
Construction worker in a tunnel operating a large red tunnel boring machine with various equipment and lighting.
Construction workers guide a large concrete section being lowered into an underground tunnel as part of tunnel or metro construction project, with overhead machinery and scaffolding visible.
A large red construction gantry crane inside an underground tunnel, with workers on the upper platform and the crane lifting a large metal beam.
Construction workers in safety gear working on a concrete building installation, positioning a large concrete beam with chains and a hoist in an industrial setting.
Underground construction site with pipes, construction lights, and tracks for a subway or train station.
Construction inside a tunnel featuring red scaffolding used for tunnel boring operations, with pipelines and construction equipment along the sides.
Construction workers inspecting inside a flood-prepared tunnel with large yellow and black pipes and red scaffolding.
Construction worker walking inside a large tunnel with concrete walls and ceiling, illuminated by lights along the sides.

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Do you have questions about our work or products, technical services, or simply want to learn more about KSS? Don't hesitate to contact us. We'll be happy to help.