That's $80 million over the initial cost estimate.

The Knik Arm Bridge and Toll Authority, which has already spent upward of $40 million on the project, announced the updated cost Jan. 29. The cost estimate was updated using the latest bid prices and an independent contractor-type estimate for the bridge based on time, materials, labor and equipment.

Most of the $680 million would be paid for with tolls paid by users, rather than taxpayers, officials said. No toll fees have been announced to date.

The bridge authority also said construction costs could decline due to the current recession and decreasing world demand for asphalt and steel products.

The updated cost estimate is for the initial construction of the bridge, as well as roughly 10 miles of road from the intersection of Point MacKenzie Road with the Port MacKenzie boundary in the Mat-Su Borough to the A-C street couplet south of Government Hill in Anchorage, including the bridge across Knik Arm.

The bridge authority was authorized by the Alaska Legislature in 2003 to develop plans for construction and operation of the toll bridge as a second connection between Anchorage and the Mat-Su Borough.

A survey released Feb. 2 by the authority claims that 60 percent of residents of Anchorage and the Matanuska-Susitna Valley want the bridge built.

"The survey results clearly show continued strong public support for this project," said David Dittman, president of Dittman Research, whose firm was paid by the bridge authority to do the survey.

Lois Epstein, director of the nonprofit group Alaska Transportation Priorities Project, disagreed with that conclusion. Epstein pointed to a section of the lengthy survey documenting a number of verbatim comments from those surveyed.

Responses included a number of criticisms of the project, including "the survey didn't mention other ways to diminish the traffic. It seems like the survey is a little slanted."

Respondents were not identified.

The full survey report is at www.knikarmbridge.com.

Backers of the bridge argue that it would decrease congestion on the Glenn Highway, the only existing route, and dramatically cut the drive time between the Mat-Su Borough and Anchorage for thousands of commuters.

Critics argue that few drivers would use the bridge, and that the environmental impact statement done for the bridge ignored less expensive alternatives, including commuter rail, car ferries and better traffic management on the Glenn Highway.

Critics have also raised concerns over potential environmental impact of the bridge to Cook Inlet salmon and beluga whales. Belugas in the area have been listed as endangered by the National Marine Fisheries Service. Gov. Sarah Palin has announced the state's intent to challenge the listing.

Margaret Bauman can be reached at margie.bauman@alaska

journal.com.