Energetic optimisation of railway operation requires reliable and easily available energy consumption data. The most convenient instrument is a database of energy consumption figures. Such a database is fed by data obtained either through on-board energy measurements or simulation of train runs.

A powerful database of consumption data has to take into account the dependence of energy consumption on a variety of parameters such as:

• Train data (efficiency of traction components, train mass, aerodynamics, train configuration etc.)
• Train service (speed, distance between stops, timetable)
• Track data (topography, curvature etc.)
• Influence of driving style
• Influence of traffic situation (unscheduled stops etc.)

A database can then help to answer questions such as:

• What is the energy consumption of one particular vehicle series compared to another one?
• How much energy could be saved by using loco-hauled or MU stock on a particular service?
• How much energy could be saved by applying constructive changes on a vehicle (aerodynamic shielding, demand-operated motor ventilation etc.)?
• What is the energy saving potential of energy efficient driving for different timetable designs?

A database for energy consumption figures can be fed by data obtained by extensive on-board measurements or through simulation.

The following table gives advantages and drawbacks of the two approaches.

	On-board measurements	Simulation
Advantages	Very precise data for individual train run possible Driving style of drivers can be assessed (energy efficient driving, use of recuperation brakes)	Less equipment, personnel and time needed Suited for forecasts
Drawbacks	Generalisation to other situations difficult Cost-intensive installation of metering equipment on vehicles Not suited for forecasts Additional costs for collection, transmission and processing of large data volumes	Influence of several additional parameters and disturbances difficult to evaluate (traffic situation etc.) Calculation of energy demand of real train runs very difficult

Source: IZT, Meinlschmidt, Seibt et al. 2001