Page 38 - 360.revista de Alta Velocidad - Nº 5

Schumann, Tilo. Meyer zu Hörste, Michael. Heckmann, Andreas. Lemmer, Karsten.

With this background, a concept for a train set of 202 m length consisting of eight coaches and
two train heads was developed and named NGT HGV , see Figure 2.

Figure 2: Side view of the NGT HGV with leading train head and first intermediate coach
Important features considered by this train concept may be summarized as follows:

• Double deck configuration in order to increase the number of seats per train length and in
turn reduce energy consumption per seat
• Ambitious light weight design and streamlined construction of carbodies and running gears
accordingly
• Use of running gears with independently rotating and driven wheels throughout the complete
train set in order to distribute traction effort, actively control running stability and reduce
wear and noise

Due to the organization of DLR, the NGT project could be organized as a joint effort of 11
institutes involving disciplines such as structural mechanics, vehicle dynamics, aerodynamics,
electrical engineering as well as systems and operational engineering.
The same wide-range expertise could also be exploited to explore the speed range up to 600
km/h and elaborate on the “reasonable upper speed limit” question posed in the section above.

3. Technical Aspects related to higher train speed

3.1 Vehicle Dynamics

Modern high speed trains are complex systems and quantities such as forces, accelerations or
wear result from the interaction of many components and environmental as well as operational
influences. In order to master a fundamental question as given, it is helpful to subdivide the
transportation task from the vehicle-dynamical point of view, which leads to three sub-tasks
each focused on one specific direction of motion, cf. [7]:

a. load bearing, that is mainly related to the vertical dynamics of the vehicle,
b. guidance, which is associated to the lateral dynamics along curved and tangential track and
c. traction in order to transmit propulsion and braking forces in longitudinal direction.

As regards a., i.e. vertical dynamics, the comfort of the passengers is dominated by forced
vibrations of the bounce and pitch motion of the vehicle, cf. [7, p. 14], which in turn are ruled
by the quality of the track and the train speed. Due to human perception, comfort is in addition
a function of the vibration frequency with the main emphasis on frequencies between 4 and 8
Hz [8].

On the one hand, measurements of non-ideal , real tracks expose a rise of irregularity amplitudes
for increasing wavelengths. On the other hand the excitation frequency, the vehicle is exposed

36 360.revista de alta velocidad