Keywords: tram, light rail vehicle, measurement, data evaluation, energy savings, smart auxil-iaries, energy storage, efficiency.

Although light rail systems are one of the most efficient modes of urban transport there is still a great potential for the reduction of their energy consumption. This paper describes concepts for future light rail vehicles to save between twenty and forty percent of energy compared to current trams. For the determination of possible savings, long-term measurement data from the Dresden Measurement Tram Project during five years of operation has been used. For evaluation, the onboard systems of the tram can be divided into three main appliance groups: traction, braking resistors and auxiliaries, including comfort systems for passengers. As most of the electric energy used for accelerating the tram is recovered by braking, the net consumption of the traction system is mainly formed by losses in the traction chain and the mechanical running resistance. A comparison of coasting vehicles shows a spread of the resistance forces between 1.2 and 6 kN at a speed of 20 km/h equalling a disparity of 40-70 MWh per year, caused by different traction chain designs. Avoiding components with high friction and cold lubricant temperatures enables significant savings. Besides the traction system, the use of energy storage devices to minimize energy dissipation in the braking resistor allows a further increase of efficiency. Savings are highest with on-board storage but trackside storage systems allow lower costs and should be preferred from an economic point of view. Concerning the auxiliaries, improvements of the heating system are most promising. Adapting the air-intake to the vehicle occupancy lowers heating consumption significantly. Smart auxiliaries, using recuperated braking energy for heating allow additional savings

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