On a Saturday tour of the viaduct, which is closed for weekend inspections, he showed KOMO 4 News the latest cracks in the 51-year-old bridge. Measurement gauges are glued to 30 individual cracks along the viaduct so that engineers can see how much and how fast they're expanding.

Since the Nisqually earthquake three years, ago this top to bottom inspection has happened every six months.

Major retrofitting has helped stabilize portions near Pioneer Square that have sunk or settled as much as half a foot.

"We can't allow settlement to occur significantly or we will break the steel inside the concrete," explained Comstock."

Comstock says a column near the Colman Ferry dock is sunk four inches and that it could be next in line for repair if it sinks another inch. He also says that would make them change their inspection schedule from every six months to every three months.

So, Seattle Mayor Greg Nickels took the same tour Saturday with members of the city council and local business and labor leaders. He announced a Congressional lobbying campaign to raise the first $1 billion to repair the Seattle seawall and replace the bridge with either a new viaduct or a tunnel.

The Alaskan Way Viaduct and Seawall Coalition says it will fight to get state and federal dollars for the project. The estimated cost of the entire effort ranges from $2.5 to $4.1 billion.

At the Saturday event the group commemorated the occasion by handing out tiny pieces of viaduct concrete. The mayor says his goal is to find the money to keep the rest from falling too.

Mayor Nickels calls repair and replacement of the viaduct the number one transportation priority for the city. Doing nothing, he says, poses a major economic threat to the region.

"This moved in the earthquake, it moved after the earthquake, and it moved again," said Mayor Nickels at a news conference before the tour. "And our job is to make sure we replace it before it moves for the last time."

A draft environmental impact statement for the project is scheduled for release in March.