The loading frequency is an important input into determining the stiffness of asphalt materials based on their dynamic modulus data. This dynamic stiffness relationship has been implemented in the 2002 Mechanistic-Empirical Pavement Design Guide (MEPDG) in order to calculate a pavement’s structural response to loading. This response, typically maximum horizontal strain and vertical pressure, are then used to estimate the number of load repetitions to failure. The Marquette Interchange Perpetual Pavement Instrumentation Project is a research effort carried out by the Transportation Research Center at Marquette University. The project implemented many different pavement sensors in order to provide researchers with a complete set of pavement response data for calibration of local design variables as well as insight into the structural behavior of a perpetual pavement opened to live urban freeway traffic. An analysis of the strain and pressure data recorded from the project was conducted in order to measure the length of strain and pressure pulse durations. The load pulse durations for each axle were then analyzed and compared to models used in the 2002 MEPDG software. The analysis showed that the models may broadly fit actual load durations, but the surrounding assumptions may not be adequate for all axle andload configurations.
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