Variations in Skid Resistance Over Time

About the report:

The purpose of this project was to quantify the magnitude of changes in skid resistance over time, to isolate the variables that seem most important with respect to the changes, and, to the degree possible, formulate a model for converting skid resistance values obtained under a given set of conditions to the values that would be measured under a different set of conditions. The Virginia Department of Highways and Transportation survey skid trailer, the Department's research trailer, the research stopping distance car, and the grease patch method of measuring surface texture were evaluated with respect to time-and weather-dependent changes in measured values. The grease patch method of measuring texture seems to have the same basic relationship to weather variables as does the Department's survey trailer, but the relationship is inconsistent among sites. Also, the use of this method is time consuming and, consequently, expensive. The research trailer experienced so many breakdowns that the researchers place little confidence in the results obtained with this testing device. For the stopping distance car it was found that the average standard deviation for all test speeds on the six sites tested was 3.26 skid numbers. For the Department's survey skid trailer it was found that adjustments could be made to measured values to predict values for times other than when the measurements were made, either by evaluating weather variables or using specified correction values for designated months.

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