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Driving safety support is one of the most attractive applications of an intervehicle communications system. Real-time and reliable packet exchange among vehicles is key to offering timely warnings to drivers in order to avoid fatal accidents. In this article we introduce multicarrier multicode spread Aloha (MM-SA) system, an intervehicle communications system developed to satisfy challenging requirements for supporting driving safety. MM-SA is based on code-division multiple access technology, and has inherent robustness to the increase of node density as well as the hidden terminal problem. We present an overview of MM-SA system including protocol design and prototyping as well as the GUI tool, which are all developed for avoiding intersection collisions. We also present performance comparison between the MM-SA system and a CSMA-based system under a realistic accident scenario. Our evaluation results show that the MM-SA system has superior performance to the CSMA-based system, and achieves the communication performance required for driving safety support.