Pavement surface distress information, collected by automated surface distress evaluation equipment, can be used in pavement management systems to plan the timely maintenance of roads and highways. Images acquired at highway speeds contain such large amounts of data that practical digital data storage systems are easily overwhelmed. Fractals have been investigated as a means of compressing pavement distress images, after the distress has already been detected in pavement images by other methods. These stored, compressed images could be analysed by computers later to characterise the severity and extent of the distress or they could be used to reconstruct the distress image for evaluation by a pavement maintenance engineer. The advantage of treating a pavement crack as a fractal curve is that it can be represented by only a few numbers. The basic fractal characterisations, including the fractal dimension, of some forms of pavement distress have been measured and are presented; a midpoint displacement algorithm that is useful for compressing and simulating distress images is described; basic methods for applying fractal models to distress image compression are discussed; a method for simulating pavement surface distress images is presented; and the use of fractal techniques to generate standard images for testing automated surface distress evaluation systems is proposed.
Abstract