SR99 Bored Tunnel-Assessment of Settlement Impacts ... - SCATnow

5.0 Automated Monitoring Total Station5.1 Goals5.2 ImplementationAutomated Monitoring Total Stations utilize prisms fastened to the buildingexteriors. They do require line-of-sight to the Total Station equipment, which may bedifficult because of obstructions in a downtown environment. The informationprovided is x, y, and z coordinates, similar to GPS stations.• Direct recording of settlements at multiple locations within line-of-sight.• Intermediate cost solution between tilt meters and GPS monitoring.• Excellent accuracy of a few tenths of an inch (claimed by manufacturers asbeing as low as 1/16 inch).Where the opportunity exists to set up a central station and fulfill the requirement ofmany accurate settlement readings within line-of-sight, reference prisms can beplaced at points to be monitored. This system is ideal for a structure such as astraight tunnel, but in a downtown location with many buildings and trees, it is moredifficult to find multiple line-of-sight conditions from a single station.A current tunneling project in Zurich, Switzerland, has prism stations attached tosidewalk curbs, giving settlement information for utilities.Reuse of central stations as the tunneling progresses would lower the cost perbuilding monitored.The Alaskan Way Viaduct & Seawall Replacement Program March 2010Proposed SR 99 Bored Tunnel - Assessment of Settlement Impacts to Buildings E-9Public Disclosure Request 11-0123 for Elizabeth Campbell - 2nd installment