Development of tools for improved spring load restriction policies in Ontario

Application of seasonal load restrictions to certain parts of the highway network can lead to lost productivity and a substantial impact on the economy. Once these restrictions are in place, the payload of certain heavy vehicles must be reduced. One of the largest challenges particularly in Northern Ontario is to design and monitor roads concisely to mitigate damage caused by seasonal effects. This is a complex problem as many of the roads are gravel or surface treated and there is limited funding available for the construction and maintenance of these facilities. Thus, it is vital that these roads are protected, particularly during the vulnerable spring thaw period. In order to properly protect these facilities, it is necessary to monitor them in a coordinated manner which utilizes both temperature and pavement data. The advancement in data availability has been greatly enhanced with the implementation of road weather information system (RWIS). This paper describes an on-going study in Ontario which has involved the installation of two thermistor probes in Thunder Bay and New Liskeard in the Winter of 2005. At each location, a thermistor assembly was lowered into the excavated area and backfilled. The design of the two pilot sites which includes the installation of thermistor strings and soil data will be described. Initial data will be presented which attempts to relate RWIS data to that observed in the pavement structure. A preliminary thaw index will also be suggested with recommendations for continued monitoring.