As the input data for the Cost-Benefic analysis, we used the figures of traffic volumes of the Straits in 2004 and also the estimated future values (year 2010 and 2020). The procedure of the estimation of the future traffic value of the Straits is as follows;

 The result of the estimation is shown in the table below and we can see that the traffic value in the Straits will be increasing constantly in the future.

　

　

 In this study, we calculated the benefits mainly from the viewpoints of the users of the Straits. There are mainly two benefits to be considered.

　

 The first benefit expected is the benefit of transportation costs, which is the reduction of time required for navigating the waters in question due to the streamlined navigation, or increase in the size of ships navigable in the waters in question, achieved as an outcome of each project. Benefits in terms of maritime transportation economy derived from the shortened time or the increased size of ships are considered as the benefit of transportation costs.

 Another benefit is that of navigation safety. It is expected that the risk of marine casualties will decrease as an outcome of each project. Economic losses caused by marine casualties include the ship's damage, ship's repair, human damage, freight damage, and the removal of the said ship. In addition, in the case that the damaged ship was a tanker, there is a danger of oil spill, so sea pollution caused by the oil spill should also be included in the economic losses.

　

 Benefit of navigation safety is an economic effect derived from the reduction in the risk of marine casualty occurrence. In this study, we consider the losses caused by marine casualties on four levels, namely complete loss, serious loss, slight loss and no loss.

　

 Probability of the occurrence of serious casualty is low, while that of minor casualty is high. It is the same idea as the Law of Heinrich. The degree of losses for each level of casualty is shown as a Damage Coefficient, assuming that the loss in the case of complete loss as 1.

　

 When calculating losses by ship's damage, ship's repair, human damage, freight damage and sea pollution, figures obtained by multiplying this coefficient are regarded as losses at each level. However, the cost for the said ship's removal is incurred only at the level of "complete loss" and "serious loss " so the cost is not included in the levels of "slight loss" and "no loss."

　

 Sea pollution is calculated as follows, because even in the case of a complete loss by a tanker, not all of the cargo oil loaded onboard flows out.

　

 First, the formula on the correlation between the size of the ship and the oil spill was prepared. Oil spill from ships other than tankers were supposed to be set as a fixed value of 1.5kl. Then, for the loss per spill, we used the figure derived from the actual data of the IOPC Fund, which is US$ 18,000 per 1kl.

　

 The figures of B/C are generally above 1.5 which is said to be effective enough for implementation. The figures of B/C are increasing exponentially, in accordance with the increase of traffic volume.

　

　

(cf.) Examples of Cost-Benefit analysis in similar projects in Japan:

Tokyo Bay Entrance Route Construction Project (planned) B/C=1.51

Kan-mon Traffic Route Construction Project (implemented) B/C=1.64

　

 In this study, we analyzed how much navigational safety improves through each project by expressing a safety index. We used here the concept of "Blocking Coefficient" as an index for safety.

　

 This, to put it briefly, is an index showing the degree of freedom a ship has to avoid another opposing ship during the navigation. The lower figure shows a higher degree of freedom. Adversely, when the density of ships increase and each ship is obliged to navigate by avoiding other ships, the figure will increase. It is generally considered that there is a navigational danger when this figure rises to 0.6 or higher.

　

 This chart is showing the Blocking Coefficient of the ease that 2 or 3 projects are implemented at the same time. Because it is actually impossible to abandon the project 2, we consider that to implement the project 2 is a base condition. As far as the situation where both project 2 and project 1 are implemented as presented by the littoral States, the current situation will be in the level of not difficult navigation, however, it will exceed 0.6 in 2020, to the level of difficult navigation.

　

　

 The volume is forecasted to increase steadily in the future, and will be increase roughly 50% both in terms of the number of ships and tonnage by 2020 compared to 2004.

　

 The results of the quantitative assessment and the cost benefit analysis of the projects showed that all the four projects in question have sufficiently high-cost effectiveness.

　

 The difficulty of navigation will increase in accordance with the increase of the traffic volume. Some projects will be essential in near future to mitigate the congestion.