• Project

I-405 - BN RR Br to Ped Trail Br & I-90/E Fork Issaquah Creek - Seismic

Project overview

In summer 2022, our contractor will begin a project in the I-405 corridor to strengthen several overpasses to help them withstand a major earthquake. They will place steel "jackets" around columns that support overpasses to help keep the concrete together in an earthquake, reducing the chance that an overpass could collapse.

Fall 2022- winter 2024
Project status
$23.2 million

What to expect

Most of this construction work will not affect people traveling on I-405 because it will take place underneath the freeway. However, people using the roads underneath I-405 where work takes place should expect lane and shoulder closures and some nighttime ramp closures. The work also may require some sidewalk restrictions, but our contractor crews will provide alternatives.

At the I-405 and SR 520 interchange, columns that support seven bridges will be retrofit with steel jackets. These will reduce the possibility the pillars could collapse in a major earthquake.