Dec. 11 project update

Posted on Dec 11 2014 1:22 PM
Crews from WSDOT and Seattle Tunnel Partners are conducting ongoing surveys of the Alaskan Way Viaduct and ground to determine whether settlement is continuing near the SR 99 tunnel access pit. In general, the surveys include:
  • Twice daily manual measurements at the bottom of both the east and west columns of the viaduct. 
  • Approximately every other day measurements of deep survey points. These are survey points more than 80 feet underground. 
  • Ground surveys of sidewalks and streets from Alaskan Way to Second Avenue and from Yesler Way to South King Street. Some areas are surveyed twice a day; other areas are surveyed once every two to three days. 
  • Surveys of some buildings. Data is collected both manually and automatically and monitored daily.
The data from the ground surveys and deep survey points are represented on a survey point data map. This map does not represent data from building surveys or the surveys of the viaduct. 
The map is a computer-generated approximation to show visually the survey results that were shared with the public on Dec. 5, which indicates approximately 1.4 inches of ground settlement near the access pit and a lesser amount of settlement in the surrounding area. It does not show differential settlement, which is uneven settlement that occurs underneath a particular building or structure. 
Lastly, the map does not present conclusions about the effect of dewatering. Additionally, the colors have been modified to better show the change in settlement from high to low.

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