About Our client

The Expressway and Rapid Transit Authority of Thailand (ETA) initiated a tenth-year bridge inspection to assess its current condition and recommend necessary mitigation measures and long-term maintenance. A major concern for ETA was the nearly continuous motion of the deck under normal service conditions. A project team consisting of OPAC, AES Group, and Kinemetrics was engaged by ETA to carry out the inspection.

Project Objective

The project objective was to install a state-of-the-art structural health monitoring system, continuously monitor structural motion, stresses, and related structural/environmental data and to remotely alert the bridge operators when any parameters exceeded specified thresholds. The system was also to measure long term changes in structural parameters.

Project Achievement

The Rama IX Bridge, one of the world’s longest span cable-stayed bridges, when completed in 1987 saw significant advancements in monitoring with the installation of the Online Alerting of Structural Integrity and Safety (OASIS) system in 1994. This comprehensive system included 12-channels of accelerometers, 3-channels for wind measurement, and 1 channel for temperature, all integrated with a Kinemetrics’ Altus data logger, and an 18-channel digital recorder with 19-bit resolution. Event-triggered data was recorded using a PCMCIA module equipped with two 20 MB solid state disks, while modified Altus firmware provided a continuous, real-time serial stream across all channels. Data was transmitted and displayed at the ETA headquarters, located approximately 5 kilometers from the bridge. The RAMA IX Bridge Monitoring System not only met every requirement set by the owner reliably but also served as an invaluable tool for bridge management, laying a robust foundation for future system expansions.