Road Weather Management Program
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Best Practices for Road Weather Management Version 2.0

Title:

Evaluation of ODOT Roadway/Weather Sensor Systems for Snow and Ice Removal Operations, Part V: Vehicular Speed Associated with Winter Pavement Conditions

Abstract:

The major objective of the study was to develop a procedure to determine the level of service using the RWIS speed measurements. The procedure developed can be used by ODOT to evaluate winter maintenance activities and for winter maintenance decision making. Average traffic speeds for five minute intervals were measured and related to the pavement and driving conditions. In addition speed data from two other studies was used. The pavement conditions were determined by conducting surveys at rest area buildings using a questionnaire form. It was found that the average traffic speeds were significantly lower during a major snow event even when periodic plowing and salting was done. The average speeds decreased almost linearly for the period of the snow storm reached the minimum and then climbed back slowly towards higher speeds. The speeds appear to be a fairly sensitive measure to judge the condition of the pavement. The motorist judgments about the pavement condition and their perception of the safety of driving decreases during a rather severe winter storm which is mirrored in the speed decrease. A simple procedure was developed for winter maintenance management to determine the condition of the road (freeways) based on the average speeds observed by the RWIS sensors. Depending on the rate of accumulation of snow, frequency of the snow plowing, length of the snow plow route, the pavement condition can improve and detoriate a number of times during a winter storm. The level of service can get worse even with maximum snow plowing and salting effort in a situation with a high rate of snow accumulation. The winter speeds observed as a percentage of the average dry surface speed can be correlated with the level of service. A relatively more fine graduation of the level of service as a function of the percentage of the average dry surface speed is proposed in the recommendations of the report.

Source(s):

Ohio University Department of Civil Engineering and the Ohio Research Institute for Transportation and the Environment, prepared for the Ohio DOT

http://www.dot.state.oh.us/research/2006/Maintenance/14758_Part_V-%20FR.pdf

Date: 2006

Author:

Zwahlen, Oner, Suravaram

Keywords:


Speed
Winter storm
Winter maintenance

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