Development of a model for finding the optimal train velocity (often an upper bound for passenger trains, but attainable by freight trains) and size for a railroad line with constant gradient, so as to minimize the sum of operating and passenger time costs. Four types of costs are considered: energy, train time, passenger riding time, and passenger headway time. Other conditions are the weight and drag of the train. Calculations give an optimal velocity of 71.0 m/sec and an optimal size of 108.8 seats; a sensitivity analysis shows that the value of time has the most pronounced effect on costs. The model could be extended to cover a line with varying gradients and to account for flow from both directions, since the assumption of a constant downgrade is not very realistic. 15 pp. Ref.
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