The departure times of trains can affect the number of locomotives needed to power the train schedule by changing the dwell time of locomotives in yards,especially remote yards. Studies at Conrail show significant potential to reduce locomotives by re-organizing the train schedule appropriately. We developed a "horsepower-flow" model that determines appropriate light-engine moves and locomotive units needed per train for a weekly train schedule, whose output is then used by a "schedule optimizer" for re-arranging train departure times while keeping weekly frequencies of trains. These models are useful for planning and comparison purposes.