Abstract
Japan is the second largest petroleum consumption country in the world. Therefore, CO_2 curtailment to prevent the greenhouse effort is imposed on Japan as an international pledge. However, the amount of CO_2 exhaust from automobiles are still increasing in Japan. Therefore, a drastic innovation of traffic policy and technology is needed. Then, the effect of jumbo trains that substantially cut the CO_2 emission from automobiles is discussed when they are integrated with the road traffic ITS.