Performance Evaluation of Traffic Speed Deflectometer Based on Virtual Standard Test Road

Abstract

It is challenging to find actual standard test roads (ASTRs) to evaluate the measuring performance of the Traffic Speed Deflectometer (TSD), leading to misjudgment of its evaluation results. To address this issue, a method to construct virtual standard test roads (VSTRs) using in-service roads is proposed. Firstly, the principle of TSD based on the Laser-Doppler effect to measure pavement deflection is introduced, and the shortcomings of traditional evaluation methods are reviewed and summarized. Secondly, an adaptive construction method for VSTRs is proposed based on the K-means clustering algorithm. It layers the Falling Weight Deflectometer (FWD) measurements on in-service roads and reconstructs them as virtual roads with stable deflections but different ranges. Thirdly, two new indexes, the coefficient of variation CV k and the influence coefficient of speed ICS k , are proposed to replace the traditional indexes, such as repeatability and correlation coefficient. Finally, the feasibility of evaluating TSD performance based on VSTRs and the new indexes is verified by experiments. Results show that the newly constructed VSTRs solve the problem that the ASTRs are challenging to obtain, reducing the experimental requirements for evaluating TSD, and the new indexes achieve an efficient and scientific evaluation of TSD.

Dynamic Measuring Method of Laser Beam Incident Angle for Laser Doppler Vibrometer

“…According to the monotonicity of trigonometric function and inverse trigonometric function in Equation ( 16): (a) when R = r − R 0 and ξ = ±R 0 /r, β mR takes the minimum value of β mR1 ; (b) when R = r + R 0 and ξ = 0, β mR takes the maximum value of β mR2 . The calculation process is shown in Equation (17).…”

“…An excellent application of LDVs in the transportation industry is the Laser High-Speed Deflectometer [11], commonly referred to as the Traffic Speed Deflectometer (TSD) [12][13][14] or Laser Dynamic Deflectometer (LDD) [15,16]. Multiple LDVs are installed on a stiff beam inside the trailer compartment of this detection instrument, which can efficiently measure the deformation velocity of the road surface under the rolling of the vehicle's weight in realtime [13,17,18] and back-calculate the deflection value based on the Euler-Bernoulli beam model. The practical results show that this measuring method is greatly affected by the incident angle of the LDV laser beam.…”