It is important for Korean government to invest on Social Overhead Capital(SOC) due to high distribution costs. However, increase in government expenditures on national defense, education and welfare system imposes heavy burden on government, making investment on SOC difficult. Therefore, the government succeeded in attracting financing from private capital to expand SOC and to lower distribution costs.

However, the government is bearing heavier financial burden because traffic demand is very much overestimated. The total expected number of daily users of Inchoen International Airport Expressway, Inchoen Airport Railroad and Inchoen Great Bridge is four times bigger than the number of actual Inchoen Airport Railroad users in 2007. Moreover, although unit cost in highway construction by private capital is supposed to be lower than that by the government, the cost of the former is actually 1.4 times higher than that of the latter. Especially BTO project on Daegu-Busan Highway is a controversial issue since the construction cost is 2.2 times higher than that of Dansin-Mokpo Highway. This paper researches the overestimated traffic demand cases and analyzes causes of high construction costs, addressing the alternatives for these problems.