Analysis of Pedestrian-Induced Displacements on a Wooden Footbridge Using Dual Total Stations and Time-Series Alignment

This study investigates whether two total stations can be effectively used together to monitor small movements of a pedestrian footbridge and to better understand how the structure responds under pedestrian loading. The purpose was to test whether a dual-station setup can detect consistent displacement patterns at corresponding points, whether time-alignment methods improve data interpretation, and to what extent submillimeter displacements can be measured using nonrobotic instruments. Two different station configurations were evaluated: one in which the instruments observed corresponding points from opposite sides of the bridge and another in which they observed different points from the same side. Measurements were collected over two consecutive days during five pedestrian flow campaigns, with displacements tracked in longitudinal, transverse, and vertical directions. Dynamic time warping was applied to align manually collected time series. The results show that the dual-station setup can reliably capture coherent patterns of bridge motion, with the same-side configuration producing consistently strong agreement between stations (typical correlations of 0.70–0.85 across components). The opposite-side configuration showed more variable correlations (ranging from 0.30 to 0.75), which reflected the bridge’s quasi-static torsional response. Across all campaigns, empirical standard deviations of observation differences were between 0.1 and 0.5 mm, confirming that the system could resolve submillimeter displacements under both light and heavy pedestrian loading. Overall, the study demonstrates that a dual-station total-station approach, combined with time-series alignment, offers a practical and precise method for structural health monitoring of pedestrian bridges.