This paper was presented at the `Transportation Technology Innovations' session. During the initial phase of SHRP Pavement Research, many low-end (piezo-electric) WIMs were installed across North America to keep track of commercial vehicle axle weights. Several in-service performance evaluations have resulted in strong complaints, aimed mostly at vendors. In contrast to in-service evaluations, investigative research into accuracy and reliability has been insufficient. This paper reports on investigative resesarch carried out at the Ministry of Transportation, Ontario in the summers of 1994 and 1995. This work is about complete for summer operation of WIMs. Some winter-specific problems remain not fully addressed. The objective was not to make over piezo WIM into a perfect weighing machine, but to systematically describe the various sources of fault and to indicate strategies developed for addressing these sources. The intention within the Ministry was to separate piezo-electric WIMs from general folklore, to investigate and document what the equipment required for upkeep was and how accurate it could be, and to let internal clients choose whether or not it was good enough for their application. (A)
Abstract