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4. Sponsoring Agency Code This document reports on the development of smoothness criteria for weigh-in-motion (WIM) scale approaches. The criteria are meant to screen sites for excessive truck dynamic loading that exacerbates WIM scale error beyond levels recommended by the American Society of Testing and Materials (ASTM). WIM scale error was related to pavement profile characteristics using a large simulation study of the response of virtual trucks over measured profiles. A distribution error was compiled over the truck population for steer axle, tandem axle, and total vehicle weight at each site. The error distributions were summarized by their 95th percentile absolute error levels. The error levels assigned to each site were then used as a correlation standard for the proposed roughness indices and for the selection of corresponding threshold values. Instead of a single index, two versions of the Butterworth filter were selected for use in the specifications. One addresses "Short Range " roughness and the other "Long Range" roughness. The Short and Long Range WIM error indices were then statistically related t