In this paper, an autonomous cruising traffic flow simulator introducing the road to vehicle communication is constructed, and the broadcast type contention schemes for road to vehicle communications are compared in realistic conditions of the traffic flow by using this simulator. The pure-ALOHA, the slotted-ALOHA, and the non-persistent CSMA schemes are examined. In simulations, the capture effect and the propagation delay including the processing delay are considered, and the required frequency bandwidth is obtained from the average packets loss rate property. Simulation results show that the non-persistent CSMA is relatively superior to the ALOHA schemes. In addition, expanding the carrier sensing areas has an effect of saving the required frequency bandwidth, and the effect of the propagation delay on the performance of the non-persistent CSMA is evaluated.