This article investigates the possibility of piezoelectric energy harvesters as energy scavenging devices in highway bridges. The structural vibration due to the motion of a load (vehicle) on the bridge is considered as the source of energy generation for the harvester. The energy generated in this way can be useful for wireless sensor networks for structural health monitoring of bridges by reducing or even eliminating the need for battery replacement/recharging. A highway bridge model with a moving point load is investigated and a linear single-degree-of-freedom model is used for the piezoelectric energy harvester. Two types of harvesters, namely, the harvesting circuit with and without an inductor, have been considered and the energy generated for a single vehicle has been estimated. These results may be used, together with traffic statistics, to obtain the variation of average power and thus, for a given application, help to design the energy management system.