indices is clearly inappropriate. Frequently, there 

 are circumstances that distort the relationship be- 

 tween watenA/ay flows and the economy described 

 by OBERS. Even when total commodity flows can 

 be adequately described through the use of indices 

 derived from OBERS projections, factors such as 

 increasing environmental concerns, changes in in- 

 ternational relations and trade, resource depletion, 

 and other factors, may seriously alter the relation- 

 ship between waterway commodity flows and the 

 economy described by OBERS. 



(c) If problems of the type described in paragraph 

 (b) of this section are identified, undertake inde- 

 pendent studies to ascertain the most appropriate 

 method of projecting commodity flows. The assess- 

 ment of available secondary data forms the basis 

 of these independent studies. These data will assist 

 in delineating the bounds on the rate of increase 

 for waterway traffic, as well as facilitate a better un- 

 derstanding of the problem. Supplement these data 

 with (1) interviews of relevant shippers, carriers, 

 and port officials; (2) opinions of commodity 

 consultants and experts; and (3) historical flow pat- 

 terns. Commodity projections can then be con- 

 structed on the basis of the results of the inde- 

 pendent studies. 



(d) Generally, specific commodity studies are of 

 limited value for projections beyond approximately 

 20 years. Given this limitation, it is preferable to 

 'extend the traffic projections to the end of project 

 life through the use of general indices on a regional 

 and industry basis. Such indices can be construct- 

 ed from the OBERS projections or other generally 

 accepted multi-industry and regional models. De- 

 scribe projection methods selected in sufficient 

 detail to permit a review of their technical adequa- 

 cy. 



(2) Sensitivity analysis of several levels of projec- 

 tions is used for the economic analysis. There may 

 be a high level projection embodying optimistic as- 

 sumptions and a low level projection based on as- 

 sumptions of reduced expectations. The high and 

 low projections should bracket the most foresee- 

 able conditions. The third and fourth levels of pro- 

 jections can reflect the with- and without-project 

 conditions based on the most likely estimates of 

 the future. If a proposed plan would not induce 

 commodity growth, one level of projection may be 

 shown for both the with- and without-project condi- 

 tions. (See Chapter I, Supplement I). 



(3) The commodities included in the projections 

 should be identified, if possible, according to the 

 following waterborne modes: containerized, liquid 

 bulk, dry bulk, break-bulk, etc. Projection-related 

 vanables include estimated value, density, and per- 

 ishability. The commodities should also be catego- 

 rized by imports, exports, domestic shipments, do- 



mestic receipts, and internal trade. Projected ton- 

 nages by trade areas both with and without the pro- 

 ject should be displayed at least for the study year, 

 the base year, fifth year, tenth year, and then by 

 decades over the period of the analysis. 



(4) Most projections of waterborne commerce are 

 static estimates of dynamic events; therefore, the 

 projections should be sufficiently current to support 

 the report conclusions. 



(d) Step 4— Determine vessel fleet composition 

 and cost — (1) Vessel fleet composition. Key com- 

 ponents in the study of deep-draft harbor improve- 

 ments are the size and characteristics of the ves- 

 sels expected to use the project. Present data on 

 past trends in vessel size and fleet composition, 

 and on anticipated changes in fleet composition 

 over the project life. Use estimates of future fleet 

 consistent with domestic and world fleet trends. 

 Undertake studies to the extent necessary to deter- 

 mine the appropriate vessel fleet. The assessment 

 of available secondary data forms the basis of the 

 independent studies. Data may be obtained from 

 various sources including the U.S. Department of 

 Transportation (Maritime Administration), trade jour- 

 nals, trade associations, shipbuilding companies, 

 and vessel operating companies. Determine the 

 composition of the current and future fleet that 

 would utilize the subject harbor both with and with- 

 out the proposed improvement. Provide adequate 

 lead time for anticipated changes in fleet composi- 

 tion for vessels that are currently a small part of 

 the world fleet. Size selection may vary according 

 to trade route, type of commodity, volume of traffic, 

 canal restrictions, foreign port depths, and lengths 

 of haul. It may not be realistic to assume that the 

 optimum size vessel is always available for charter; 

 the preferred approach is a fleet concept that in- 

 cludes a range of vessels expected to call with and 

 without the project. It is suggested that tabulations 

 in the report show composition of vessel fleets by 

 deadweight tonnage for each type of vessel begin- 

 ning with the current fleet and by decades through 

 the period of analysis. Histoncal records of trips 

 and drafts of vessels calling at the existing project 

 should also be displayed. 



(2) Vessel operating costs. To estimate transpor- 

 tation costs, obtain deep-draft vessel operating 

 costs for various types and classes of foreign and 

 United States flag vessels expected to benefit from 

 using the proposed improvement. Since vessel op- 

 erating costs are not readily available from ocean 

 carriers or from any central source, the Corps of 

 Engineers, Water Resources Support Center, will 

 develop and provide such costs on an annual basis 

 for use in plan evaluation. Planners should deter- 

 mine to what extent these estimates of vessel 

 costs must be modified to meet the needs of local 



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