The determination of optimum number of berths under given conditions is one of the inevitable problems for all civil engineers engaged in port and harbour planning, but, their conclusions concerning this problem are, in most case, far from clear cut.
　One of major difficulties in this problem is forcasting the amount of cargo handled, another is estimating cargo handling capacity in a given project.
　An approach from the point of view of Operations Research has been proposed for the latter problem, cargo handling capacity especially of general cargo berths.
　The problem was formulated into Waiting Line type model of multiple channels, with possion arrival and Erlang service.
　Veridity of this model has been checked by the obser vations in two leading terminal ports in Japan, namely, Yokohama and Kobe.
　Solutions has been derived analyticaly and also by simulation. The discrepancy between the solutions derived by those two methods is satisfactorily small.
　The system's behaviour not only under the steady state, but also under the transient state has been studied and tables summarizing steady state solutions are in cluded.
　Lee-Longton's conventional formula has been reexamined in several cases and shows fairly good approximation.