Part of Alaskan Way Viaduct has sunk up to 1/4 inch in past month, but still safe, state says

SEATTLE -- Survey crews have confirmed that part of the Alaskan Way Viaduct has sunk up to one-quarter inch in the past month, but bridge experts are confident this does not pose new safety risks, the Washington State Department of Transportation said Friday.

The settlement occurred on the viaduct between South Main Street and Railroad Way South, WSDOT said.

"The viaduct remains vulnerable to earthquakes, but it is still safe for everyday use," WSDOT said. "If we had any reason to believe the structure was unsafe, we would not hesitate to close it.

"The viaduct has been settling for years, as you can see in our inspection log. Hundreds of monitors have been installed in the ground and on the viaduct to help us monitor settlement, and we will continue to keep a close eye on the structure’s condition as construction continues."