6 Rail vehicles
Judging from the world stock of locomotives, rail transport systems are of highest importance in Europe, followed by Asia and North America (Chart 10). Data for multiple unit sets reflects a similar picture ([UIC 2000]). It is therefore not surprising that many data have been gathered from Europe and will be discussed in this section.
Chart 10: World stock of locomotives World stock of locomotives [*1000]
Source: [UIC 2000]
North Africa/ Middle East
Sub Sahara Africa
Trains are composed of several elements, generally locomotives and rail cars. Since rail cars do not have an engine of their own, all energy will be consumed and saved via the locomotive. Therefore, whole trains will be considered for a realistic estimate of the energy savings by weight reduction. These trains, however, will show great variations in terms of weight and energy consumption, mainly depending on the number of rail cars they are composed of. „It is [therefore] proposed that the energy consumption be used in the units of kJ/tonne-km. By making the consumption mass specific, the major factor in determining the energy consumption, the train mass, has been normal- ized out of the calculation. In these terms, energy consumption for different train types becomes more similar, and correlations based on mass specific energy consumption will be applicable to a wider range of trains” [JORGENSEN & SORENSON 1997]. Final energy savings for rail vehicles are thus much rather stated as relative energy savings in % final energy savings per 10 % weight reduction [%/10 %] instead of kJ or kWh per 100 km and 100 kg weight reduction. This procedure allows to calculate the specific energy savings directly from the specific energy consumption.
Mainly electric trains have been investigated because they are the most common options in Europe with a high data availability. First we will discuss the relative energy