STILL SINKING State department of transportation engineers hope construction of deeper pilings and new footings will stop further Viaduct sinking. Columns of the Alaskan Way Viaduct, between Columbia and Yesler streets, continue to sink with the latest inspection showing they dropped another 3/8 inch in the last six months, totaling 5 1/2 inches since the Nisqually earthquake in 2001.<br><br><b>Photo by Matthew G. Miller</b>
A section of the Alaskan Way Viaduct continues to sink, but state crews have almost completed work to stop it.
Bents 93 and 94, the pairs of columns and their cross braces between Columbia and Yesler streets, sank another 3/8 inch, bringing the total misalignment to about 5 1/2 inches. The most recent measurements were taken during the semi-annual inspection of the viaduct March 22 and 23.
At 6 inches, engineers with the Washington State Department of Transportation said repairs would be required. Rather than wait until it was necessary, or too late, work began last October.
Crews have driven micropiles, steel rods and concrete, around the four sinking foundations, and then another 30 feet deeper into stable soil. Each of the rod can carry 95-tons. The perimeter of micropiles will support the structure through new concrete footings.
"We expect our work will cause more settling," said Dave Dye, deputy director for the Washington State Department of Transportation, "until the structure nestles into the new piles."
Repairs on the west pair of footings is complete. The east pair will be finished by the first week of May.
The patch will help keep the central portion of the viaduct standing until it is razed in 2012.
Matthew G. Miller may be reached via wseditor@robinsonnews.com.
