Abstract: Analysis of road surface roughness on the three axle vehicle random excitation input, using
white noise method and the transfer function method is used to derive the vehicle six rounds of road
roughness input state equations are obtained. In Matlab/Simulink to build a two-dimensional
pavement roughness mathematical model, and standard pavement roughness the comparison and
validation, indicating the accuracy of the model to build. Through the vehicle state equation to build
six rounds of pavement roughness mathematical model. The simulation results show that the with the
axle of the power density of the two wheels of the spectrum differences, on the same side of the front
and rear wheels of power density spectrum difference of smaller, more in line with the actual situation
of multi vehicle bridge heavy truck and in order to further validate the simulation results, the
correlation coefficient of the road roughness of the six round of the vehicle is analyzed, and the
results are consistent with the above conclusions.

Key words: road surface roughness, state equation, integral unit white noise method, correlation analysis