A bit of the Alaskan Way Viaduct has been destroyed by man, before it could be taken by nature.

A bit of the Alaskan Way Viaduct has been destroyed by man, before it could be taken by nature.

Friday night after rush hour, at 7:24 p.m., a tall machine with a lobster-shaped claw sheared a green lamppost, then chewed through concrete guardrail, as crews began to demolish the northbound onramp at First Avenue South.

Nearly a decade has passed since the Nisqually earthquake of Feb. 28, 2001, inspired the long political campaign to replace the elevated sections of Highway 99.

Small chunks fell. A worker sprayed water on dust clouds. First Avenue occasionally shuddered from the force as the machine punctured the concrete deck.

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The task by Skanska, the state’s contractor for highway rebuild in Sodo, moved so briskly that the first span turned to rubble in 20 minutes, said Ron Paananen, program administrator for the state Department of Transportation, who had exchanged a high-five with Seattle Councilmember Jean Godden.

The job is part of a controversial $3.1 billion program to replace the viaduct with a new highway, including a $2 billion, 1.7-mile tunnel below downtown buildings.

Tunneling can’t begin until late summer, but the DOT already is constructing a Sodo segment that flies over the BNSF Railway lines and leads to an interchange between the sports stadiums and the container port.

The old northbound ramp will probably be severed from the viaduct by Saturday morning, said project director Matt Preedy. The old southbound exit was diverted a few days ago to a “frontage road” west of First Avenue. By April 1, a new northbound detour ramp will be attached — to be used until the tunnel is supposed to be done in 2015.

Skanska, successfully built new highway connections a few blocks away, for the western terminus of the 3,020-mile Interstate 90.

Friday night’s doomed ramp was first used April 4, 1953, as one end of the original viaduct route.

Two vehicle lanes were squeezed into the northbound ramp, while two lanes exited southbound. Then in 1959, the viaduct was extended to Spokane Street.

“People were proud of it in those days,” said Godden, a 79-year-old former newspaper columnist. “They thought L.A. had their aerial freeways, and now we had them.”

Bob Larson, of Normandy Park, recalls that around 1950, waterfront congestion was terrible. After serving in the Korean conflict, he returned home to a new highway.

“Traffic was a lot better with the viaduct,” he says. Larson recalls saving time driving from West Seattle to see a girlfriend on Queen Anne Hill.

Though DOT has a signed tunnel contract in hand, the environmental-impact statement isn’t finished, and a pair of initiative campaigns seek to thwart the project.

Regardless, by early-2012 the frontage road and temporary north ramp will be rejiggered to carry the main Highway 99 traffic, separated from First Avenue, until the Sodo viaduct stretch is razed and rebuilt. But there will be only two lanes each way in the detour corridor. A trip to Queen Anne will take several minutes longer.

Mike Lindblom: 206-515-5631 or mlindblom@seattletimes.com