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Q2 Z2,(Q2) Z2(Q2) - Institute for Water Resources - U.S. Army

Q2 Z2,(Q2) Z2(Q2) - Institute for Water Resources - U.S. Army

Q2 Z2,(Q2) Z2(Q2) - Institute for Water Resources - U.S. Army

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atch as it travels from origin to destination or, alternatively, as<br />

engaging in a production run.. Job lots are usually discussed in the<br />

operations research literature; 20 however, batch production functions<br />

are reported in Smith. 21 Also, the linchaul process seems to provide<br />

an example of the type of production <strong>for</strong> which volume of output (i.e.,<br />

the aggregate output produced during one production run) should be dis-<br />

tinguished from the rate of output. 22 A given volume linehaul movement<br />

(e.g., 100,000 ton-miles) can occur at a variety of rates (e.g., dif-<br />

ferent sized locomotives will pull the same cargo tonnage at different<br />

speeds). It would be interesting to investigate the behavior of mar-<br />

ginal costs when volume is varied at a given rate and vice versa. That<br />

is, what effect does increasing length of haul have on costs given the<br />

rate of output? And, in transporting a given amount of cargo a given<br />

distance, what effect on costs results from varying the rate of output? 23<br />

Once the linehaul process function has been obtained, one may in-<br />

vestigate the various productivity relationships, isoquants, and re-<br />

turns to scale. It is also possible to obtain cost curves <strong>for</strong> tHe<br />

linehaul process. However, due to the complexity of the linehaul pro-<br />

cess function, it may not be possible to obtain the functional <strong>for</strong>m of<br />

the expansion path and to derive therefrom functional <strong>for</strong>ms <strong>for</strong> the<br />

cost curves. Cost curves may be obtained from the process function<br />

by holding input(s) constant at various levels and varying the other<br />

input(s), calculating the total cost of each iteration. (In the cases<br />

worked out below, there are ultimately only two inputs: one represent-;<br />

ing the cargo vehicles and the other representing the motive vehicle.<br />

Labor, fuel, etc. vary in known ways with these two inputs.) The<br />

13

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