Proceeding of the Joint International Symposium on Deformatuon Monitoring. 2-4 November, 2011. Hong Kong. China. Report. Efficient construction of a Bridge Monitoring Systems (BMS) is typically achieved using a wide array of sensors. Currently bridge construction is developing at an unparalleled speed in comparison to previous ones in terms of both the performance role and project scale. To effectively operate BMSs to match this pace of bridge construction, it is necessary to consider the performance roles of monitoring sensors. This research investigates tilt-meters that monitor the absolute inclination angle that are used for assessing the inclination of the pylons of in-service bridges and the pylons and deck of bridges under-construction. It is an unfortunate reality that regulations regarding the number and location of tilt-meters are currently not well formulated in most countries with rapid bridge development. In such situations, the location and number of tilt-meters are being operated at the personnel's discretion on each construction site. In this research, the minimum number of tilt-meters required for each type of bridge is derived. Data collected through tilt-meters is compared with tilt estimation based on collected Global Positioning System (GPS) data. Current BMS have entered a new phase with the availability of high-precision satellite-based sensor technology. BMS based on Global Navigation Satellite Systems (GNSS) technology are widely spreading. As long as the required system accuracy is achieved, it is thought that this system exhibits outstanding performance in terms of efficiency and interoperability compared to previous BMS. In this research, comparative research was conducted by collecting both GPS and tilt-meter data. On the basis of the results of this comparative study, GPS appears to be a more worthy approach for bridge monitoring systems to assess the inclination angle of a bridge's structure in terms of both efficiency and accuracy. Finally, the expected efficiency with regards to monitoring inclination of the pier and deck was described.