Construction plans and ideas for keeping the viaduct open and moving during the Alaskan Way viaduct and seawall replacement project were released last week.

"Regardless of what we build, the project is located in the same dense urban area and the impacts will be similar, so we can start planning now for construction." said Project Director Ron Paananen. "We know a great deal more than we did two years ago about what construction will look like and how it will affect commuters."

It has been two years since the project's original draft environmental impact statement was released. The new version updates the design, including improvements north of the Battery Street tunnel and documents the impacts related to the project's two alternatives for replacing the Alaskan Way Viaduct - a cut-and-cover tunnel or an elevated structure.

The supplemental draft environmental statement includes three possible construction plans: shorter, intermediate, and longer.

"With either alternative, two-thirds of the project is the same. The central waterfront portion is the only area that's different. So, we can begin to get public feedback on the trade-offs during construction," said Paananen. "We are asking if the public wants a shorter construction duration or do they prioritize keeping the viaduct corridor open as much as possible?"

Regardless of the approach, the team is preparing a thorough mitigation plan.

"More than $100 million will be available for traffic mitigation to help alleviate congestion and help people get to and around downtown," said Grace Crunican, Seattle Department of Transportation director. "We successfully used this approach when we invested $16 million on traffic improvements to help prepare for the downtown transit tunnel closure."

The documents released today outline many of the potential strategies the state and city are considering to keep commutes bearable and downtown livable during construction. The potential strategies range from a new off-ramp for buses and drivers from the Spokane Street Viaduct, to an extended bus-only lane on southbound Aurora Avenue. Analysis of these strategies is ongoing. A draft Construction Transportation Management Plan will be released later this year.