Nightly construction work continues along the I-90 corridor, with the eastbound lanes restricted from the I-90 floating bridge through all four Mercer Island exits.

According to WSDOT, the construction is part of its “two-way transit project” to add HOV lanes to the I-90 outer roadway between Seattle and Bellevue. The project also includes building new I-90 HOV and off-ramps on Mercer Island and improvements to I-90 HOV access at Bellevue Way.

Asked what the roadwork entailed, WSDOT spokeswoman Annie Johnson said crews are working to preserve and strengthen a three-mile section of eastbound and westbound I-90 through a process called “dowel bar retrofit.” The process strengthens the roadway and extends the life of the pavement.

“It’s preventative,” she said, adding that WSDOT has received several questions about the “bumpy” manner of the road. “Right now things are kind of bumpy, but we’ll come back for the grinding process. That will smooth the roadway out.”

Johnson added that the I-90 roadwork is in preparation for light rail’s East Link train in 2020.

“It’s kind of a precursor to the light rail coming,” she said, adding that the new HOV lanes, both eastbound and westbound, will replace “the capacity that the center [HOV] roadway on I-90 is losing for light rail.”

Crews will only be working at night. Island exits remain open with neon signs diverting drivers around the orange construction cones.

This month’s eastbound I-90 construction is part of stage two in WSDOT’s two-way transit project.

At the end of April, construction will move forward when crews add HOV lanes eastbound between the exit ramp at 80th Avenue and Bellevue Way. Stage three, which will begin in 2011, entails adding HOV lanes from 80th Avenue to the Rainier Avenue exits in Seattle.

The entire project is expected to be complete in 2014.

More information can be found at www.wsdot.wa.gov/Projects/I90/TwoWayTransit. Click the “Pavement Preservation” subheading for specific project details.