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.
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