Barrier coverage is one of the most important issues in wireless sensor networks. In the literature, many studies have proposed solutions to the barrier coverage problem. However, most of them discussed the traditional application which aimed for intruder detection and used the Boolean sensing model (BSM). In fact, the barrier coverage issue can be applied to the new application of traffic count. This paper proposes two barrier coverage mechanisms, which consider the new application of traffic count and applies another sensing model, called probabilistic sensing model (PSM), which assumes that the sensing probability of a sensor is a probabilistic value depending on the distance between the sensor and object. As compared to BSM, the PSM model is more practical since it considers the interference and other environmental conditions. The proposed two barrier coverage mechanisms, called (weighted based working scheduling) WBWS and (connectivity based working scheduling) CBWS, aims to reach the predefined monitoring quality of barrier boundary while satisfying the minimum numbers of sensors. Experimental study reveals that the proposed WBWS and CBWS mechanisms outperform existing related studies in terms of surveillance quality and hardware cost.