D. Surface Transportation In the preceding section on SPS materials, the transport of material from the launch site to geosynchronous orbit was considered in the materials requirements for the SPS; to complete the picture the logistics of getting the material to the launch site needs to be considered. To develop a plan for ground transportation, it is necessary to start with raw materials and trace the entire transportation of materials in the manufacturing sequence to the launch site. No accurate detailed attempt is made to do this at this time. However, rough assumptions are made to obtain an insight into the approximate ground transportation requirements in support of SPS manufacturing. The cost of transportation of raw materials is reflected in the cost of these commodities. For the SPS, it is assumed that on the average, materials will pass through two contractors at different locations. From the final contractor, the material will pass to the launch site. Figure IXD-1 shows typical flow of material from raw material source to launch site using typical transport means. As the logistics are more closely studied, the percentages above can be refined. The costs of these various means of transportation are well known both in terms of dollars and energy expenditures, and flow rates can easily be established once construction schedules have been established. This, in turn, will establish the warehousing and handling facilities at intermediate points. As has been shown in the program requirements section of this report, the construction rate could typically grow from one-half an SPS per year to seven SPS's per year in a 30-year period. The total transport requirement based upon the scenario of figure III-2 would grow from 8.6 X 10' metric ton km/year to around 1.2 X 1010 metric ton km/year. Warehouse and transport facilities would be expected to increase by up to a factor of fifteen. Some information is available to check the realism of our model of ground transportation requirements for the SPS. In reference IX-2, it has been noted that correlation between intercity freight movements and the commodity component of the gross national product is very close. Both items increased at an annual rate of 3 percent from 1979 to 1958, and correlation was almost perfect between the two series on a year-to- year basis. The services component of the gross national product was about 38 percent of the GND in 1960 and is expected to increase to about 40 percent in the year 2000. Table IXD-1 shows the projected metric ton kilometer for goods and construction for the year 2000.
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