In this paper, the preliminary application of a new type of cement-based piezoelectric sensor developed recently for monitoring the traffic flows is proposed and investigated. The sensor was made by bonding between two cubes of hardened cement sand paste with a commercially available piezoelectric ceramic plate encapsulated by a new sealant developed especially for the sensor's fabrication, and its property was tested by dynamic loadings including harmonic loading, random loading, and pulse loading. Two experiments were carried out to prove the feasibility and reliability of the sensor for monitoring the traffic flows including the person flow and the vehicle flow in the field of transportation. The tested results show that the sensors can correctly respond to the pulse loadings induced by walking person or passing vehicle and the responses of sensors were approximately direct proportional to the peak values of pulse loadings. A conclusion is given that there is a good potential for the cement-based piezoelectric sensor in the engineering application for monitoring traffic flows in the field of transportation. © 2006 ASCE.