T h e G e o r g e W a s h i n g t o n U n i v e r s i t y L o g i s t i c s R e s e a r c h P r o j e c tThis paper describes a comprehensive transportation network model which exploits the special capabilities of large-scale, high-speed computing equipment in the evaluation of large complex transportation schemes. The model was developed to approach the fundamental requirement to compare quantitatively the performance of different transportation force levels against the cost of procuring, maintaining, and operating these force levels. Specifically, in the execution of contingency plans, different force levels of airlift and sealift were to be evaluated in measurable terms of total lift over time which could then be weighed against the cost requirements for each combination.A transportation network comprised of terminals and connecting links (arcs) was constructed so as to represent the transportation environment associated with a specific contingency plan selected for the prototype model. Only inter-theater lift was considered, so the model network extended from the present locations of the military load in the CONtinental United States (CONUS) to the final destinations in the objective area. Each link (arc) represented a route and a mode of transport. All available modes and feasible routes were included. Each terminal had a through-put capacity and each arc a transit time and capacity. In addition to pure transportation arcs, control arcs, inserted at critical points, restricted through-puts to the level of the particular capacity constraints at those points. The performance of the different lift systems was evaluated through this network model. Ford and Fulkerson [4]and the corresponding directed paths and path flaws determined.ance evaluated, and a cost analysis made.The network was solved for maximal dynamic flows using the algorithm developed byThe number and type of carriers required in each run were determined, their perform-The following assumptions and restrictions were incorporated into the network model: 1. The terminals selected for inclusion in the network were:a. The points of origin of Army forces and supplies, i.e., forts, camps, stations, and prising the particular logistic plan for Southeast Asia. Over-the-beach capabilities and airlift organic to the theatre were not included in the model, nor were inland waterways. 261

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T h e G e o r g e W a s h i n g t o n U n i v e r s i t y L o g i s t i c s Research P r o j e c tTo establish a perspective, a discussion is made of the over-all planning process involved in the determination of military requirements for the merchant shipping needed to support a prescribed military plan.Three of the principal p a r t s of the planning process, namely: the determination of "pure" pipeline requirements, ship repair loads, and repair replacement ships, under convoy and nonconvoy conditions, a r e examined. After this, the newly developed models, assumptions, and methodologies for these a r e dissected and illustrated by means of figures.Typical characteristics and behavior of both the nonconvoy and convoytype pipelines and the effect of the repair policies upon them a r e presented. planning process and which require further research, a r e outlined.Additional logistics problems, which were generated in the The logistic problems to be described are concerned with the determination of the military requirements for the merchant shipping necessary to support a prescribed military plan. By using this information, plus comparable data on the merchant shipping requirements of the civilian economy under the same plan, a capability study will be made to see whether available merchant ship resources a r e adequate to meet the requirements.In order to establish a perspective, the general problem area of the over-all planning process i s outlined in Figure 1. (Parts of the process a r e already in being, others are being worked on, and others are yet untouched. At this point the term "notional ship" is used to mean a standard reference ship in terms of which actual ships can be expressed. This equivalence will be discussed in more detail subsequently. ) been developed for three principal parts of this flow sheet, namely: the determination of "pure" pipeline requirements, ship repair loads, and repair replacement ships.ments from each service. The lift-requirement data covers cargo (M/T), 1 POL (bulk)(Bbls), personnel (number), delivery schedule, origin (source), and destination.Measurement ton is the space available for cargo measured in units of 40 cubic feet to the long ton (2240 pounds).We shall now examine in detail the models, assumptions, and methodologies that have 545