Long Term Bearing Capacity on a Secondary Highway

Abstract

Since 1993 county road W850 in Central Sweden has been subjected to falling weight deflectometer measurements on an annual basis. Road surface characteristics measurements were also carried out twice per year to monitor among other things seasonal variation. Other data collected include deflections from a fast rolling deflectometer, georadar data, material sampling from coring and visual inspections. The research from these data includes initial and permanent deformation determination; frost heave influence on roughness; and several follow ups on overlays and other maintenance actions. Two reports have been presented previous BCRRA conferences and have been published in the proceedings. The present paper is a synthesis of the vast data collected. First and foremost the long term change of the bearing capacity is presented. A comparison is done to the functional properties, collected by the surface characteristics tester. Then, some conclusions are made on the maintenance and rehabilitation efforts, which were decided by traditional means. For instance if bearing capacity data are used diligently before maintenance actions are taken, the deterioration rate could be lessened. If not, poor sections continue to perform poorly even after rather expensive actions. Overall, the as built condition plays an important part of the road performance even after fifty years after the construction date. Bearing capacity measurements are good investments also for the lesser categories of roads