focus of a weight reduction for freight trains. Direct energy savings have thus not been studied. From the average consumption of a DB long distance train with 1000t gross weight of 21 Wh/ gross t-km, the energy consumption (EC) as a function of the weight in analogy to the method in [SCHWANHÄUSSER et al. 1986] and [TEMA 2000] for elec- tric traction [IFEU & SGKV 2002] (see values in Tab. 25) has been estimated:
ECtrain [wh/ km] = 315 * Mtrain [t]0,6
EC M train t r a i n
specific energy consumption per train-km total gross weight of train in t
Specific energy savings can be calculated for a 10 % weight reduction. For this calcula- tion it is not considered if the weight will be reduced at the locomotive or the wagons. The energy consumption will be reduced by 6 % for a 10 % weight reduction.
According to [ANDERSSEN 2000], aerodynamic resistance still contributes 40 - 50 % of the total energy consumption of average European freight trains, because of disadvantageous aerodynamics. This supports the calculation above, though it must be noted that aerodynamic resistance is also linear dependent on the length of the train [LUKASZEWICZ 2001]. A conservative value of 5 % will be used for exemplification, because the share of acceleration resistance will be lower for U.S. freight trains as for European freight trains. This value is also plausible, because it is between the values for passenger trains with higher speed and the regional trains with more stops. Freight train characteristics can also be very different, e. g. with much longer and slower trains in the U.S. compared to European trains. Indirect energy savings by a higher cargo capacity are of great importance. The indirect energy savings will be dealt with in the corresponding section. The values for relative energy savings in Tab. 18 will be used as reference data for the different rail vehicle categories.
Tab. 18: Overview of relative specific energy savings for exemplification
Relative energy savings [%/ 10%]
Subways/ Urban trains
Short distance trains
Long distance passenger trains
High speed passenger train (ICE)
Long distance freight trains (electric)
Long distance freight trains (diesel)
Source: IFEU 2002 from various sources