The startinglocation of the vehicle is set at [ - ̃ ( - )⁄ ⁄ ] away from the first simulationpoint on the bridge, so that the first point of the vehicle on the bridge, is located at the firstre-divided point in the first segment.Auto-PSD matrixAs the vehicle travels, the auto-PSD of the vehicle-bridge united system changes accordingly.The auto-PSD matrix of the three different periods can then be presented as Equations (14),Equations (15) and Equations (16):