In this paper

the field test of a traffic monitoring system based on a novel cement-based piezoelectric traffic sensor which is durable

inexpensive and can work under any weather conditions are presented.A concrete beam with two piezoelectric sensors respectively embedded at its two ends

as a sensing element

is designed to be installed under the wearing course of highway.Four beams

two pieces in two rows

are installed in one lane

for counting traffic flow according to the number of peaks in the responses of sensors

recording the speed of vehicles in terms of the time shift between the responses of two sensors in two rows and the distance of two rows

and measuring the gross weight of vehicles using the amplitude of peaks in sensor′s response and calibrated sensitivity of the sensor.After installation of the beams

the field recalibration using a known-weight truck is carried out for checking the validity of the sensors.Online running of the developed traffic monitoring system installed on the exit road of a highway bridge in HK was performed.The results of field test show that the traffic monitoring system can correctly measure the volume

speed and gross weight of vehicles

which indicates that the system has a good potential to be used in management and health monitoring of highway bridge.