Adding a third connection from north Issaquah to downtown, the City’s I-90 Undercrossing project will build a new north/south road under Interstate 90.

Location

The new two-lane road will start at the traffic signal at Gilman Boulevard, adjacent to the U.S. Post Office, travel northeast and connect into the rail corridor behind Gilman Station. 

It will then travel north, cross under the existing I-90 overcrossing and utilize the existing paved roadway within the former railroad right-of-way, which is now owned by King County Parks as part of the East Lake Sammamish Trail. 

The new roadway will then form a tee intersection at Southeast 62nd Street and continue north along 221st Place Southeast to Southeast 56th Street.

Benefits

Currently, there are only two connections between north and downtown Issaquah: state Route 900 and Front Street. Both of these crossings experience significant traffic congestions during peak hours. The two crossings also provide access to I-90, mixing local traffic with traffic created from the freeway’s on/off ramps.

The third new crossing will not only provide additional capacity, but also improve mobility by allowing local traffic to cross I-90 without mixing with regional traffic.  

By relieving traffic congestion near the freeway’s on/off ramps, the I-90 Undercrossing project will also have significant positive impacts on the I-90 corridor, which is a facility of both state and national significance.

Since a portion of the new roadway will be located within the existing Burlington Northern Railroad Corridor, which was purchased by King County and is part of King County Parks Master Trail Plan, it will serve as a multi-modal facility, including possible future extension of the trolley.

Status

Construction started in May 2010. The project is divided among two contractors: MidMountain Contractors, Inc. and SEACON Construction Management. 

The new road is scheduled for completion by the end of 2010.

Contact

For more information, contact:

Gary Costa

Transportation Manager