Abstract：By using a laser profiler, the surface height variations of three types of road, concrete, brick and soil roads, were obtained. Fractal dimensions of three types of road profile roughness were calculated by root mean square method, which were 1. 845, 1. 689 and 1. 561, respectively. The results showed that the road surface gives irregular performance and statistical self-similarity, which means that each portion can be considered as a reduced-scale image of the whole. A higher fractal dimension means a more complex road surface profile, and thus a unit area is more extensively covered by the profile curve. On the contrary, a lower fractal dimension presents only a limited amount of details. The concept of road roughness index was proposed in order to evaluate the quantification of road roughness. Road surface roughness index is defined as a combinative parameter of fractal dimension and root mean square deviation of road surface profile. Such a definition exhibits a unique performance when applied to quantify road surface roughness. Differences among three contrasting road types were found to be great, indicating a fractal dimension of 1. 237, 3. 435 and 14. 610, respectively, for concrete, brick and soil road.
2008, Vol. 29 
