Project overview
Through summer 2023, our contractor crews strengthened three bridges on Interstate 5 so they can better withstand a major earthquake. They wrapped steel “jackets” around the columns that support the bridges to hold the concrete together in an earthquake, reducing the chance of collapse. They also added concrete and reinforcing steel between the girders that support the bridge to keep them from moving in the event of an earthquake. The guardrail was replaced, as well.
What to expect
Work on this project is complete.
Beginning in summer 2022, we strengthened overpasses at two locations - Northgate Way in Seattle and Maple Road in Lynnwood. This will help the overpasses to avoid collapsing in a major earthquake.
We retrofitted bridges that carry I-5 over Northgate Way in Seattle and where Maple Road goes over I-5 near Lynnwood.
This work is part of our seismic retrofit program, designed to help our critical infrastructure survive a major earthquake. Being able to quickly move supplies to affected areas is vital to earthquake recovery and our highways play an important role in that.
The columns that support overpasses have rebar inside them to provide structural strength, but in a major earthquake the concrete can still crack; if enough becomes dislodged the columns could collapse. Adding steel jackets will help keep the concrete in place, reducing the chance of a collapse and keeping the highways open to deliver supplies to aid recovery.