With the development of wireless communications, Vehicular Ad Hoc Network (VANET) has received considerable attention on information sharing and data delivery services. In order to collect and control traffic conditions, Intelligent Transportations Systems (ITS) has deployed a number of Road Side Units (RSUs) along the roads to collect and deliver traffic information to the Traffic Control Center (TCC) for analyzing traffic data. Although some VANET architectures have been proposed based on the predictable routes and schedules of buses, none of them considered taking advantage of such traffic infrastructures which already been supplied by ITS and combine them with scheduled buses. In this paper, we propose a two-tier BUSVANET that is fully integrated with RSUs and TCC as traffic infrastructures. In this new architecture, the communications of vehicles, not only benefit from the existence of buses, but also consider the effects of using RSUs and TCC. RSUs are used to ensure service coverage while TCC is helpful for locating the destination vehicle quickly. We also investigate how much benefits can be obtained by taking advantage of this type of traffic infrastructure.