Development of Pedestrian and Structural Safety Monitoring System for Cable-Supported Pedestrian Bridges

Abstract

A number of cable-supported pedestrian bridges have recently been constructed or are planned in Korea, primarily by local governments. These structures include cablestayed and suspension bridges, with or without pylons. Some are intentionally designed to sway. However, the structural behavior of these bridges is not fully understood, and monitoring system have not been implemented, unlike for other road and railway bridges. This ongoing research involves the development and application of various sensors and monitoring systems to assess pedestrian and structural safety on a representative pedestrian bridge. Long-term monitoring data are being collected to investigate structural behavior and performance. To measure displacement and movement, a GNSS (Global Navigation Satellite System) was installed at the midspan and anchorage blocks. Using latitude, longitude, and altitude data with RTK (Real-Time Kinematic) correction, sag as well as static and dynamic displacements are calculated in both horizontal and vertical directions. Threeaxis acceleration data are used to determine vibration frequencies and damping ratios, revealing the bridge’s dynamic characteristics. Additional parameters—such as deck and anchorage inclination, cable temperature, and wind direction and speed—are also monitored to ensure structural safety. For pedestrian monitoring, camera-based AI technologies are employed to estimate pedestrian loads and detect abnormal behaviors of pedestrians. Object recognition and tracking algorithms estimate the number and locations of pedestrians, while pose estimation combined with LSTM (Long Short-Term Memory) networks detect behaviors such as intentional cable shaking or leaning over railings. All monitoring components are integrated into an IoT system equipped with an embedded AI computing platform. The results of this research are expected to provide a practical remote monitoring system for pedestrian bridges and serve as a basis for establishing design and evaluation criteria for cable-supported pedestrian bridges.