| Road authorities in resource based economies are frequently challenged by the demands of heavy equipment operators requiring access to remote sites during sensitive spring thaw conditions. Access to these sites is rarely along high volume, structurally engineered pavements, and many secondary pavements suffer premature deterioration as a result. To overcome this, agencies impose restrictions to overloads which can result in substantial costs to operators as equipment is broken down and re-assembled onto multiple flatbeds for transportation over provincial roads. This research presents the results of a field study of the loads imposed by heavy oilfield cranes (with hydraulic suspensions and super single tires) on thin membrane asphalt pavements in Alberta. Three 150 m (492.1 ft) test road sections (thin asphalt wearing course, bituminous surface treatment and granular surface) were built and instrumented for strain at the bottom of the asphalt layer, surface deflection, and subgrade pressures. Temperature and moisture profiles were also measured. Field testing involved controlled speed experiments of standard axle configurations and heavy (12,000 kg (26,456.5 lb)) axle vehicles with and without hydraulic suspensions. This research presents a description of the test road design, instrumentation, and testing plan; followed by the preliminary results and findings from the four response measurements focusing on vertical stress in the subgrade, longitudinal interfacial strain, and surface deflection of the of the test road. Finally, a methodology is presented for determining an acceptable number of trips of these vehicles on a highway without increasing the resultant damage. |
