Abstract: Reasonable, accurate, and real-time impedance functions are prerequisites for dynamic traffic induction of urban roads, which is also a classical problem in traffic planning.At present, there are few studies on the dynamic changes of traffic capacity and impedance function of city secondary road, especially under influences of illegal parking.For massive taxi GPS data from Wuhan, a screening strategy of massive GPS data for different road scenarios and taxi operation statuses are put forward to calculate travel time.Smats portable Bluetooth and Wi-Fi scanner equipments are used to collect traffic flow.According to the working principle of the equipments, a corrective method for error data is developed, and then the correspondence between actual data of traffic flow and experimental data is obtained.At last, the changing regulation of road traffic capacity under illegal parking is introduced into BPR impedance function, and its coefficients are calibrated by actual data.The accuracy of the function is verified.Compared with the traditional BPR method, the results show that the mean error of the recalibration BPR method is reduced from 26.1 s to 6.8 s.