This paper proposes a technique for fast detection of pavement ruts based on laser triangulation. For the real-time measurement of ruts, transversal projection is applied to confine the valid region of laser curve, followed by segmental line fitting to eliminate gross errors. Bezier curve fitting is applied to form
a continuous smooth curve representing the road profile. To improve the measuring precision, instead of obtaining parameters of laser triangulation equations and calculating object coordinates of the laser curve, a calibration grid construction method based on triangulated irregular networks (TIN) and the back-calculation algorithm from image points to their object coordinates are proposed. Experimental results show that the algorithm is capable of sampling the road surface 80 times per second. The results of automatic measurements are in general agreement with that of the manual measurements. Therefore, the proposed method is effective and reliable for pavement rut measurement.