Measuring Mach 8 Sub-millimeter Survey System Jun 1, 2007 By: J. Clark Hughes, Joel A. Banks, Aaron J. Kerkhoff, Brian W. Tolman, Rex E. Ellison

The Benchmark Survey System, developed for the U.S. Air Force's Holloman High Speed Test Track. replaces legacy NGA conventional survey techniques with a GPS-only system, maintaining sub-millimeter positioning accuracy while increasing throughput by 400 percent, with an 85 percent decrease in manpower. Results agree with recent NGA precise survey data to better than 0.6 mm horizontal and better than 1.0 mm vertical.

Innovation: Dam Stability Assessing the Performance of a GPS Monitoring System Oct 1, 2006 By: David R. Rutledge, Steven Z. Meyerholtz, Neil E. Brown, Cory S. Baldwin

A precise and modernized monitoring program is an important component of the U.S. Army Corps of Engineers' long-term risk-management plan for hydroelectric structures. Recent work at Libby Dam in Montana demonstrates that GPS deformation monitoring systems can accurately track displacements at critical points, making it an important asset in ensuring dam safety.

Bridge Deflection Monitoring — Tracking Millimeters across the Firth of Forth Feb 1, 2006 By: Gethin Wyn Roberts, Chris Brown, Xiaolin Meng

Kinematic GPS trials with dual-frequency surveying grade code- and carrier-phase receivers measure 3D displacements of Scotland's Forth Road Bridge to millimeter precision. Researchers also found that measured frequencies of bridge movements compared well to the bridge frequencies obtained from finite element models.

Steep-Slope Monitoring GPS Multiple-Antenna System at Xiaowan Dam Nov 1, 2005 By: Xiufeng He, Wengang Sang, Yongqi Chen, Xiaoli Ding

Although GPS is an efficient tool for deformation monitoring, it also is an expensive one for large projects. The authors developed a remote-controlled monitoring system using an electronic switching device for multiple antennas to monitor steep slopes at the Xiaowan hydropower station in China.

Millimeters in Motion Dynamic Response Precisely Measured Jan 1, 2005 By: Ana Paula C. Larocca, Ricardo Ernesto Schaal

Brazilian researchers devised a way to detect dynamic millimetric displacements in large structures using single-frequency GPS receivers. They combine interferometry, satellite geometry, and a novel analysis of L1 double-difference phase residuals of regular static observations over a short baseline.

The Height of Precision Sep 1, 2003 By: Tracy Kijewski-Correa, Ahsan Kareem

GPS sensors track wind-driven displacements of Chicago skyscrapers and provide the first full-scale insight into structural response that will help produce better building designs.

Real-Time Kinematic Spans the Gap Modern cable-supported bridges carry enormous loads across great distances, in part due to their designed capability to move, ever so slightly, under varied conditions. In Hong Kong, a real-time kinematic (RTK) GPS monitoring system provides the centimeter-level accuracy, in all weather conditions, to detect bridge movements beyond normal ranges. Engineers can then conduct inspections or maintenance needed to maintain longterm structural health. Jul 1, 2001 By: Kai-yuen Wong, King-leung Man, Wai-yee Chan

Hong Kong's Tsing Ma Bridge is the world's longest span suspension bridge carrying both road and rail traffic.