This paper proposes an efficient Harmony Search (HS) algorithm for determining the material parameters of a fatigue cracking model based on Accelerated Pavement Testing (APT). APT is preferred over typical laboratory experiments and testing because APT can simulate field pavement performance. The main advantage of the HS heuristic algorithm is its ability to find the best global solution of a nonlinear complex function based on a stochastic random search instead of a gradient search that requires derivative information. Finally, this paper develops a fatigue cracking model according to the hypothesis of cumulative damage for the asphalt concrete layer and compares APT to existing models. In comparison with existing models, the APT model is found to have the capability of simulating the field performance because it considers the wandering effect, resulting in longer fatigue cracking life than those life computed by the models from existing lab experiments.
PURPOSES :This study aims to suggest the optimal spacing between speed humps which is placed at traffic calming areas including pedestrian priority zones, school zones, and residential areas.
METHODS :The study measured the operating speed of vehicles passing through two successive humps by using laser gun in 0.2 seconds interval, and analysed the basic statistical characteristics of speeds data to have an insight on the relationship between spacing and speed. Assumption was made to derive the maximum spacing within which two successive humps influence each other.
RESULTS :The statistically significant model explaining the relationship between spacing and 85th percentile speed of vehicles was derived as well as the maximum spacing maintained in order to take the benefits of successive installation of humps.
CONCLUSIONS :Spacing of 20 meters was suggested to achieve the widely accepted target speed of 30 km/h in traffic calming zone, and spacing of 70 meters was suggested as a maximum spacing. The comparison across the studies were made and empirical reasoning the difference of results between studies was discussed as well as the future studies.
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