Influence of Slow-Moving Nature of Super Heavy Load (SHL) Vehicles on the Service Life of Pavement Structures

Trucks transferring super heavy load (SHL) typically weigh several folds of the permissible weight limits set forth by regulatory agencies. Operation of such vehicles with heavy wheel loads and nonconventional axle arrangements can result in substantial loss of service life of transportation facilities. Such detrimental impacts are more significant, considering the slow-moving nature of SHLs and time-dependent behavior of viscoelastic asphalt layers. This was the motivation for our research team to develop a framework to quantify pavement life reduction (PLR) associated with the slow-moving nature of SHL vehicles. To achieve this objective, our research team initially deployed portable weight-in-motion (P-WIM) devices to ten sites with high frequency of SHLs in Texas. Subsequently, nondestructive field tests such as falling-weight-deflectometer (FWD) and ground-penetrating-radar (GPR) were performed during summer and winter months for back-calculation of the layer moduli. The field-derived data were in turn incorporated into a 3D finite element code for the characterization of pavement responses under different SHL-vehicle speeds. The numerical simulation results showed that slow movement of the SHL vehicle can essentially impart higher level of damages on the pavement structures compared to the same vehicle traveling at conventional highway speed. The increase in the cumulative damages associated with the slow-moving nature of the SHL vehicles can potentially jeopardize the longevity of pavements structures and result in premature failure of transportation facilities. Analysis of the representative pavements sections in this study revealed that inclusion of the slow-moving nature of SHLs into the damage assessment algorithms can result in significant PLR as high as 36%. Consequently, analysis of the slow-moving nature of the SHL vehicles should be an integral component in risk management studies of overload corridors.