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Best Practices for Road Weather Management Version 2.0

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Title:

Development of a Winter Severity Index for Salt Management in Canada

Abstract:

This paper discusses the development of two winter severity indicator models that can be used to evaluate the relative harshness of a winter in comparison with a base period. A winter severity index is a measure of the relative impact of winter weather on winter road maintenance operations using historical meteorological or road weather information system data. Winter road maintenance data were collected from across. Salt usage in tonnes (salt (t)/lane-km/day) was chosen as the dependent variable, standardized to account for differences in road network and the number of days in the observation period. The first model developed based on meteorological data alone achieved a goodness of fit of 0.54. Explanatory variables were based on snowfall occurrence, air temperature, freezing rain occurrence, and an east-west dummy variable. A second model was developed based on meteorological data together with road weather information system data. This achieved a goodness of fit of 0.60, but was based on a significantly smaller sample size. In this model, pavement temperature was substituted for air temperature. An Index was developed based on the predicted values using a scale between 1 and 100. Calibration factors were developed for twenty different homogeneous groupings across Canada using the Bayesian method. Based on the calibration, thirteen of the twenty groups achieved a better goodness of fit compared to the national model results. The model results show a better performance in heavily populated areas and in eastern Canada. Limitations of the models and recommendations for further research are presented in the paper. Key Word: Winter Severity Index, winter road maintenance, salt management

Source(s):

86th Transportation Research Board (TRB) Annual Meeting, Synectics Transportation Consultants Inc. and University of Toronto (Canada). For an electronic copy of this resource, please direct your request to WeatherFeedback@dot.gov.

Date: 2007

Author:

Suggett, Hadayeghi, Andrey, Mills, Leach

Keywords:


Winter storm
Winter maintenance
Weather information
Road Weather Information System (RWIS)

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