Author(s):
R.A. Zimmer, E.G. Fernando
Publication Date
May 2013
Abstract
Accurate estimates of wet roadway friction are critical to the safety of the traveling public, project selection, and for managing the wet weather accident reduction program. Currently, Texas is the only state that uses a one-channel, torque-type wheel transducer to measure the drag force. The Texas Department of Transportation (TxDOT) uses the measured horizontal drag force and the computed value of the dynamic vertical wheel load to determine the skid number from its ASTM E274 friction measurement system. This research project evaluated TxDOT's existing method for measuring pavement surface friction. Given the differences found in skid measurements from tests conducted to compare one- and two-channel locked-wheel skid systems, researchers investigated options for improving TxDOT's current friction measurement method, particularly on nontangent sections where inertial loading effects were found to be most pronounced. Measuring the dynamic vertical test wheel load was the primary focus of this investigation. In addition, researchers investigated improvements that could enhance the overall operation of the TxDOT skid measurement systems and reduce maintenance costs. Researchers recommend that TxDOT convert its current fleet of one-channel locked-wheel skid trailers to two-channel systems that provide direct measurement of vertical load and consider purchasing at least one fixed-slip system to support project-level forensic investigations.
Report Number:
0-6619-1
Keywords:
Fixed-Slip Friction Measurement, Locked-Wheel Friction Measurement, Pavement Friction, Skid Number
Link(s):
Document/Product
http://tti.tamu.edu/documents/0-6619-1.pdf
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