Traction Energy Cost Reduction of the WMATA Metrorail System

An energy cost reduction study was conducted on the Washington Metropolitan Area Transit Authority Metrorail system. Its primary objectives were to classify primary energy end uses and identify conservation methods which have the highest potential for reducing the electric bill. The effort involved analyzing present energy costs, developing cost- effective conservation strategies, determining the savings associated with the strategies by simulation, recommending appropriate strategies for implementation and outlining a program for executing the recommendations. Although the effort involved both traction and support energy, only the traction energy aspects of the study are reported. It is the first time that the energy management model developed for the transit industry by the Rail Systems Center at Carnegie-Mellon University was comprehensively applied to a rapid transit property. The application was verified by comparing the simulated results to actual data. For anl practical purposes, the simulated results agree to within three percent of the actual energy consumption. Four traction energy conservation strategies were recommended for implementation based on high benefit and low cost. These are coasting, passenger load factor improvement, planned catch-up operation, and regeneration of braking energy. All of these strategies have payback periods of less than three years.