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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

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The data <strong>for</strong> Table 4.4 were obtained from a common carrier barge firm<br />

which operated on the Lower Mississippi, the Illinois, and the Ohio.<br />

Active time, which is used <strong>for</strong> the base in the percentages, includes<br />

all delays and running time but excludes any time during which the<br />

towboat was undergoing major repairs or <strong>for</strong> which it was tied up <strong>for</strong><br />

long periods. Although loading and unloading time is quite small<br />

relative to other delays <strong>for</strong> these data, this delay factor could be<br />

large <strong>for</strong> contract carriers whose boats are often required to wait .<br />

during loading and unloading. In any case, the subsequent analysis •<br />

will not consider this terminal delay. If an analysis of loading and<br />

unloading were available, however, it could be included in the tow<br />

process function as an additional T in Equation (4.1). Below are<br />

analyzed locking delay, T L , making and breaking tow, Tm and Tb , and<br />

miscellaneous delays, T. In addition, the frequenc) of miscella-<br />

neous delays will be examined.<br />

Locking. Instrumental in analyzing the benefits and costs of a<br />

waterway investment is the determination of the waterway capacity and<br />

the delay involved in locking. In addition, locking time is an im-<br />

portant component of the tow process function. There<strong>for</strong>e, a method<br />

is desired <strong>for</strong> predicting the waiting time in queue and in lock <strong>for</strong><br />

a tow operating on a waterway with several locks. The model, to be<br />

discussed in this subsection, should be sensitive to changes in total<br />

tonnage carried on the waterway (i.e., demand <strong>for</strong> transport), changes<br />

in lock capacity, and changes in flotilla characteristics. <strong>Water</strong>way<br />

capacity considerations will be taken up in the next subsection.<br />

87

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