Influence of climate and traffic on the HMA rut-depth for India

Rutting is one of the major distresses observed in bituminous pavements. In the majority of the design approaches including the Indian Road Congress (IRC) guidelines for the design of bituminous pavements, the rut depth is predicted by limiting the vertical compressive strain at the top of the subgrade. Here, due consideration is not given to the rutting in individual layers of pavement. There are more than 20 variables that influence rutting in the pavement with the degree of influence of the variables differing for each layer. The analysis performed in this study is limited to the rutting observed in bituminous layers (HMA rutting) and the factors influencing it. Several factors influence the HMA rutting, and among them, traffic and climatic characteristics play a critical role. In this study, traffic data was collected for 12 National Highways across India, and appropriate weather stations were identified. Detailed weather data was collected for all these locations on an hourly basis. Using this information, simulations were carried out in AASHTOWare to generate the rut depth data. For the HMA rutting, it was seen that the pavement temperature distribution played a critical role compared to the maximum pavement temperatures. The degree of influence of Average Annual Daily Truck Traffic (AADTT) on the HMA rutting was, however, found to depend on the pavement temperature strongly.