4.3　Routing selection simulation In this chapter, the routing selection between the NSR and the Suez route is studied to optimize the freight costs. The results from chapter 4.2 imply that the Suez route should be selected when the ice condition is harsh. The ice forecast based on advanced satellite technology will be realized in the future, we will be able to predict the ice conditions for one or two months in advance with a sufficient reliability before entering the NSR. Based on this scenario, the simulation is attempted for some periods of the historical ice data. Namely, the decision for switching the Suez route is made using the cumulative ice index, The annual serial voyage simulation (ASVS) was performed using 50BC and 10 year data from 1980 to 1989. The ice breaker tariff cut by 26% was used as depicted in Table 4.1.1 and N-route was selected. The mean ship speed in the Suez route is set to 17 knot and the voyage days are 36 days including the harbor days. The results of the simulation are summarized in Table 4.3.1 showing for the NSR part, the Suez route part and annual total for each year. The mean value of the output distribution is shown in Table 4.3.1. The results obtained from 90%-tail value and 10%-tail value of the distribution are noted in the Appendix D. 　 Table 4.3.1 Summary of annual serial voyage simulation (ASVS) 　 The average annual voyage number is 10.2 times/year and the number of NSR voyages is 9 times/year. Thus, approximately 88% of the voyages are through the NSR. The freight costs vary from 20.3 to 21.6 \$/ton. As shown in the Appendix D, the freight cost as the results from 90%-tall value and 10%-tail value ranges from 20.7 to 21.8 \$/ton and from 20.3 to 21.5 \$/ton, respectively. Table 4.3.2 indicates the details of 1987-simulation results. The number of Suez route voyage is just one time a year. The number of voyage is 9.3 times/year for using the NSR and 10.3 times/year for a total. The voyage days in the NSR ranges from 28 to 45 days. The mean ship speed during One voyage is from 7.8 knots to 13.7 knots. The freight cost in the summer season of 1987, which is calculated from the results for 12th June to 11th October in Table 4.3.2, is 18.8 \$/ton. On the other hand, it is 22.3 \$/ton as for the winter season from October to May. The freight costs for 1987 are estimated to be \$20.8/ton as shown in Table 4.3.1. The freight costs in other years show the similar tendency by season. The summary of the above results is; the freight costs for the ice-strengthened 50BC range between 20.3 and 21.6 \$/ton, under the suitable route switching between the NSR and the Suez route by every voyage. As for only the Summer season (about 4 months), the freight costs are 18.8 \$/ton and is nearly equal to that of the Suez route employing the conventional handy size bulker derived as follows. 50,000 DWT handy size bulk carrier (C-50BC), whose particulars are shown in Table 4.3.3, is assumed as the conventional cargo ship for the comparison.