2025 Volume 81 Issue 15 Article ID: 24-15016
Methodologies using track geometries measured on the traveling train are rapidly developing to estimate railway bridge deflections, which have been measured on site one by one. However, the theoretical relationship between track geometry and bridge deflection obtained using two-bogie track inspection vehicles frequently used in domestic railways and the bridge deflection estimation method remain unclear. This study theoretically derives that the maximum value of the difference between the two track geometries obtained by a two-bogie track inspection vehicle is proportional to the maximum value of bridge deflection. In addition, a method is developed to estimate bridge deflection using a conversion coefficient from the maximum value of track geometry difference. As a result of field validation on actual railway, the following findings were obtained. Estimation accuracy is low with conversion coefficients based on single beam theory due to the influence of adjacent bridge deflections. By using a simple correction method that can be applied when bridges of the same type are consecutive, the estimation accuracy can be improved to an error of about 5% for a target bridge.
