Railway manufacturers usually specify energy efficiency of their products by giving efficiency at payload and/or idling losses. They are difficult to verify and do not tell much about the effective energy consumption in real operation. The reason is the strong dependence of efficiency on operation point (speed, force).

Some operators avoid this problem by including a specific operation profile in the call for tender. However, this makes only sense in cases where the planned field of application of ordered stock is very narrow or even restricted to one single line. More often this will be the case in smaller and/or less dense networks. If the operation profile is less specific, a standardised set of reference cycles for energy efficiency could help to make the issue more transparent between industry and railway operators.

For diesel stock reference cycles exist for exhaust emissions (UIC and EURO I-IV standards). In contrast, for electric stock no reference cycle exists which properly represents operation, i.e. there's no convenient way to compare the energy efficiency of an Alstom and a Bombardier locomotive. A standardised set of reference cycles accepted by all manufacturers would allow railway operators to effectively compare the energy efficiency of different products. At the same time it would provide a means of verification of manufacturer specifications. A reference cycle is a well-defined vehicle trajectory (e.g. run vehicle … kms in level topography with speed … and force …, then … kms in up-hill with a slope of … etc.) containing a representative weighting of load situations. Obviously there would have to be separate reference cycles for freight, high-speed, local operation.