Pacific Northwest Geodetic Array
Central Washington University

Pacific Northwest Geodetic Array

Central Washington University

Alaskan Way Viaduct
The half-century old Alaska Way Viaduct (SR99) was damaged by the 2001 Nisqually Earthquake and has subsided 13 cm since that event. Following the catastrophic 2007 collapse of the Interstate 35W into the Misssissippi River, which killed 13 and injured 145, Central Washington University, the WA Dept. of Transportation, and the WSRN decided to continuously monitor the Alaska Way Viaduct with GPS. To better quantify the long-term stability of this aging structure, its probability of failure, and its risk to society, several real-time telemetered, high-sample rate GPS receivers were installed along the Viaduct. Along with ~350 other GPS receivers that
comprise CWU's Pacific Northwest Geodetic Array (PANGA), these instruments acquire GPS satellite phase measurements and transmit this information to the CWU and the WSRN, where they are independently analyzed. The raw satellite phase measurements are converted into position estimates on a continuous basis. The mm-accuracy measurements of bridge deformation are computed 24 hours per day, 7 days per week, and fed into alarm algorithms that notify Viaduct stakeholder and emergency responders in the event the Viaduct begins to deform anomalously. Following the Viaduct installations, additional GPS instruments were installed on the SR 520 bridge and are currently being installed on other bridges, and dams, as well as a variety of other structures around Washington State and the greater Pacific Northwest. All data from these stations in analyzed by CWU.

Structural Instrumentation

Real-Time Initiatives

  • Dam Safety
  • Critical Sctructure Analysis
  • Deformation Monitoring
  • Post Event Evaluations (Rapid)
  • Slope Failure and Mass Movement
Alaskan Way Viaduct
SR520 Floating Bridge
Tolt Dam

Real-Time Network Explanation

Orignal Text From:
About the WSRN - Washington State Reference Network The WSRN (Washington State Reference Network) is a regional cooperative of GPS reference stations and data that enables cost-saving solutions for public and private sectors in the fields of surveying, mapping, and other high accuracy location technology needs.

Participating entities include: The cities of Seattle, Renton, Bellingham, Kent, Auburn, and Shoreline; The counties of King, Snohomish, Skagit, Island, Jefferson, Thurston, and Pierce; Kitsap Public Utility District, the Washington State Department of Transportation and the Spatial Reference Center of Washington (SRCW); academic and scientific institutions and projects like the Pacific Northwest Geodetic Array (PANGA), Central Washington University, and Renton Technical College.

Real-Time Networks, a timely solution. Though fairly new to the U.S., these types of networks have been very successful in Europe and Asia where networks span entire countries where utilization is spreading beyond surveying to mapping, utilities, emergency response, agriculture, forestry, public safety, transportation, machine control for construction, environmental, and scientific research.

Great examples of successful networks are SAPOS in Germany, the Jenoba and Nippon GPS Data Services in Japan, and the new statewide network hosted by the Ohio Department of Transportation. Cost savings can be substantial. High accuracies at high speed: By following proper procedures, users can observe locations to centimeters in seconds. There are WSRN users who are quite willing to share their success in utilizing the system, and test accounts can be arranged.

Network Grid

Real-Time Network Partners

Central Washington University (CWU) -Interested in localized tectonic movements of the greater Puget Lowlands. The PANGA Lab has provided the necessary GPS expertise and has donated antennae, communications, data archiving, and mounting.

Seattle Public Utilities (SPU) -Operates Trimble Integrity Manager, completed very successful RTN outperforming manufacturer and academic expectations

United States Geologuc Society (USGS) -Provided use of existing instruments

Seattle Department of Transportation (SDOT) -Interested in future applications