Time-varying traffic load model of expressway based on long-term monitored data from multiple regions - A case in central and eastern China

Traffic load is one of the main loads borne by highway transportation infrastructure, which seriously impacts the safe operation of the bridge and road. Due to the change in the external environment and government policy, the traffic load has obvious time-varying characteristics, which is the key to establishing the real traffic load model. The two main time-varying factors of traffic load are the growth of traffic volume and the evolution of vehicle weight. In the long-term research work, there is a lack of research based on continuous monitoring data for the above two factors. Therefore, this paper carries out a study on the time-varying traffic load model of expressways based on long-term monitored data from multiple regions. Firstly, the data sources of monitored 18 expressways in central and eastern China are introduced. Secondly, the Logistic model is selected as the basic model to study the growth laws of expressways from different provinces; meanwhile, the evolution of vehicle weight distribution is also analyzed and a simplified model is established accordingly. Finally, a case study of a newly opened eightlane expressway is operated to characterize the influence of time-varying vehicles. The results show that the traffic volume and vehicle weight distribution change significantly with the increase of service time. The Logistic model and liner model are appropriate to characterize the evolution model of the traffic volume and vehicle weight distribution separately. The time-varying characteristics of traffic load have a significant impact on the standard fatigue traffic load model and the cumulative equivalent axle loads. The research results could provide a reference for the establishment of time-varying traffic load standard models for highways and the revision of related standards. At the same time, it could provide technical support for the full life-cycle investigation and design of the road and bridge infrastructure.