The state, county and city executives have postponed deciding whether a surface couplet or an elevated structure will replace the aging Alaskan Way Viaduct, deferring to pressure to consider a bored tunnel despite its cost.

A joint statement was issued Tuesday, Dec. 30, by Governor Chris Gregoire, King County Executive Ron Sims and Mayor Greg Nickels.

"As a result of the continued overwhelming response and input on replacement options from stakeholders," the statement read, "we have asked our respective transportation teams to continue their review."

A final recommendation will be made to the state legislature in January, it said.

The state's commitment to the project is $2.8 billion, of which almost $1.1 billion has been spent or is committed to Moving Forward projects: new footings for four sinking columns between Seneca and Yesler streets, moving utilities off the existing structure; improvements to fire safety and lighting in the Battery Street Tunnel, retrofitting the section of the viaduct from Lenora Street to the tunnel, and replacing the southern mile of the viaduct with a new interchange.

From components of eight scenarios studied since July, the city, county and state departments of transportation recommended two hybrid scenarios: an Alaskan Way-Western Avenue couplet with a package of improvements to city streets, the interstate and transit, and an elevated bypass.

The Alaskan Way Viaduct Stakeholders Advisory Committee, and various industrial, manufacturing and business groups, have encouraged them to continue study of a bored tunnel as an essential component to any surface scenario.

"We are concerned that a surface option may lack the capacity to accommodate further growth," wrote John Creighton, president of the Port Commission advising the Port of Seattle, in an e-mail to the three directors of the departments of transportation, Dec. 17.

"An aerial option could provide the capacity we need, but it may create significant construction impacts on the waterfront and limit the potential to create new connections between the waterfront and Seattle's downtown."

The problem is cost.

The surface option is estimated to cost an additional $2.2 billion, the elevated bypass an additional $2.3 billion.

A surface scenario with a bored tunnel could cost an additional $3.5 billion.

Only $1.7 billion is left of the state's commitment.

People are encouraging the departments of transportation to consider not only the initial capital costs for tearing down the viaduct and replacing it but the long-term benefits as well.

"These include providing economic benefits that may exceed capital costs over the lifetime of the structure," Creighton wrote.

The departments of transportation will take two tacks in January: better estimate the cost for boring a tunnel and, they hope, lower it; and find other funding for a more expensive project.

"The replacement of the Alaskan Way Viaduct will have a lasting affect on Seattle and the Puget Sound region," the joint statement read. "It is imperative that we find the best option that addresses not only financing, but also solves safety, economic, capacity, and environmental concerns.

"We only have one chance to do this right," it concluded. "We owe it to the residents of the Central Puget Sound to make the right decision."

The state legislature convenes Jan. 12.

Matthew G. Miller is a freelance writer living in West Seattle. He can be contacted through bnteditor@robinsonnews.com.