Using road weather information systems (RWIS) to optimize the scheduling of load restrictions on Northern Ontario's low-volume roads

Seasonal shifts in moisture and temperature within the pavement can affect the bearing capacity of the roadway, especially in Northern Ontario where low volume roads are challenged by frequent freeze-thaw cycles. Seasonal load restrictions (SLR) are implemented every year on Ontario's secondary and tertiary highways to protect the road infrastructure. However, each time loaded trucks are allowed on a weakened pavement, premature deterioration of the roadway occurs and maintenance expenses increase. Conversely, when the payload is unnecessarily restricted, the transportation and resource industries are penalized. These economic losses are due to the reactive approach of SLR timing, historically based on patrols and expert judgment instead of systematic monitoring of the pavement condition. Road Weather Information Systems (RWIS) form a network of automated climatic stations designed largely for supporting winter maintenance operations in Ontario. A study conducted by the Ontario Ministry of Transportation and based on two experimental sites located in Northern Ontario found a reasonable correlation between frost thickness in the roadway and RWIS variables. As a follow-up to this analysis, frost predictors have been developed this year and are presented in this paper along with the results of cracking simulations using the Mechanistic-Empirical Pavement Design Guide and typical Northern Ontario conditions. Based on variables provided by the online RWIS database and Environment Canada forecasts, models would indicate changes in relative pavement strength. Real-time and cost-effective guidelines could then be derived and translated into a decision-support tool that assists MTO engineering professionals in the implementation of load restrictions.