Calculation of the Damages on Ultra Heavy Loads on Road Networks on the Basis of Service Life Performance of Flexible Pavements

Every year, a considerable amount of money is spent on construction and maintenance of road networks. In this regard, enough care should be taken in the utilization and protection of expensive asphalt layers. One of the main causes of pavement deterioration is heavy wheel loads, which unfortunately occur very frequently in Iran. These loads reduce pavement life and result in the pavement deterioration before their predicted useful life. The damage caused by these wheel loads must be calculated so that the road authorities could compensate for imposed costs. In this study, KENLAYER software is used for analysis of pavement behavior against heavy loads. Moreover the reduction of pavement design life for each load is calculated based on allowable repetition of each load and according to Asphalt Institute criteria for fatigue and rutting strains. Finally, the equal amount of expense for each load is calculated based on the reduction of allowable repetition. Results of this research show that the weaker the body of the road, the more destructive will be the effects of heavy axes on the road. It may seem that the cost of heavy loads in freeways and expressways is more than costs of two way roads but it is not practically like this. According to some studies in USA and Canada, the costs of passing axes on low traffic roads (¬and naturally on roads with weaker pavements) may be so much higher than the costs in stronger roads. Therefore it may be claimed that when heavy loads pass through expressways and freeways less damagers would occur to the pavements