Starting next year, Washington State Convention Center wants to expand by putting in a new building between Pine and Howell streets and Ninth and Boren Avenue.

Drivers are anticipating that the construction will cause even more backups in downtown Seattle.

Thursday night, transportation engineers gave the public a preview of what to expect.

Michael Swenson, a transportation engineer with Transpo Group, helped work on a more than 400-page report about the possible impacts of the Washington State Convention Center addition.

"It is a complicated project with extensive analysis that we've done," said Swenson. "Both Olive Way and Howell Street are very major and critical links for the city. The project is building underneath Olive Way, so there will be a couple years where Olive Way is shifted from its current alignment."

It is a project that will involve about three years worth of construction.

"Whether you are here or you are in south downtown, whether you are in Mercer or South Lake Union, there's lots of activity and lots of growth going on, and like any of those projects, patience is key," said Swenson.

Read the NEPA Draft Environmental Impact Statement for the Washington State Convention Center.