Weigh stations are separate areas along the highways where trucks are stopped and weighed. Weigh-In-Motion (WIM) systems offer a convenient replacement for weigh stations as they can estimate the load of a moving truck without disrupting the traffic flow. However, current technologies in WIM systems are either very costly or lack accuracy. In this report, a low cost Weigh-In-Motion system using a MEMS accelerometer is proposed. The system uses transient vibrations of the pavement to estimate dynamic load of the moving truck. A fully functional sensor board, capable of measuring the low amplitude transient vibrations of the pavement due to a dynamic load, was developed and tested. A model for sensor output is proposed and the device is thoroughly calibrated to determine the various parameters included in the model. The sensor can successfully resolve accelerations less than 200 ug and compared well with a reference accelerometer when tested for its frequency response. The sensor was installed in a concrete pavement and it was tested to be immune to sound and other external noise on the road. A Falling Weight Deflectometer (FWD), which simulates the load applied by an actual truck, was used to excite the pavement and the data collected from our sensor compared well with data collected from FWD's sensors. A low weight truck, although much lighter than commercial trucks, was driven over the sensor and the sensor successfully measured the resulting vibrations in the pavement. In addition, the measured signal was used to identify the individual axles.

Author's Note: This report, along with more future work, will be used as author's M.S. thesis and the purpose of this report is to summarize the work done so far.




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