We decompose the social costs in using transport facilities, expecially road facilities, into the internal and external costs. When economic agents drive their cars and use roads, they have to bear the road construction and maintenance costs, which is internal costs. They create air pollution material and greenhouse gases, which are external costs. Until now, Korean government impose fuel taxes on gasoline, diesel, and LPG for transport without considering the social costs.
We compare the fuel taxes with the social costs in gasoline, diesel, and LPG. Especially, we compute the external costs per liter or per kilometer as well as the internal costs per liter or per kilometer in gasoline, diesel, and LPG. We use these costs to compare with the fuel taxes of gasoline, diesel, and LPG. In considering environmental external costs such as air pollution damage costs and greenhouse gas costs, the fuel tax rates of gasoline and diesel are above and below each their social costs respectively. The fuel tax rates of LPG are almost similar to its social costs.