Page 42 - 360.revista de Alta Velocidad - Nº 5

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

is (with high-speed, freight and regional trains) the more line capacity gets lost. For a speed
over 200 km/h it is difficult to operate mixed traffic lines [30]. Many of the HSLs in the world
are used exclusively by high-speed trains: Ligne a grande vitesse in France, Shinkansen in
Japan, Passenger Dedicated Lines (PDL) in China and Lineas de Alta Velocidad (LAV) in Spain.
The different gauge between HSL and the old network in Spain and Japan prevents these lines of
being used by conventional trains. In Germany most of the HSLs are built to allow mixed traffic
all the day. The advantage is a better line utilization and a more efficient freight train operation
due to shorter route length, low gradients and possibly longer trains. Due to safety reasons
in tunnels and capacity restrictions the freight traffic is limited to the night time when there
is no passenger traffic. The disadvantage is this concept is the lack of time for maintenance
works which has to be done with track or total line closures [31]. In France or Japan HSLs are
completely closed for intensive maintenance all the night.

To increase the capacity of an HSL the trains should be operated at the same speed. For this
also trains with more stops (comparable to the Kodama trains on the Tokaido Shinkansen in
Japan, which stop every 15-50 km) have to use strong motorized vehicles [32].
A general problem of increasing the speed of passenger trains is a growing disparity between
the operational effort (energy, wear, etc.) and the travel time savings. The travel time reduces
in a hyperbolic way, the additional benefit diminishes with higher speed, but the effort grows
exponentially.

4.1 Optimized Traction force with very high speed

For the operational analysis special train models for 300, 500 and 600 km/h are derived from
the specified NGT 400. For the 300 km/h level also a special version of the NGT is used and not
existing HSTs to preserve comparability.

The dimension of the engines increases drastically with the speed. The 400 km/h version has
to handle 18 MW driving power whereas the 600 km/h version has to be designed with at least
40 MW. The latter value doesn’t include efficiency losses and power demand of auxiliary and
comfort systems so the electrical systems have to be designed with significantly more power.
Usually trains are designed with additional traction force for instance to handle gradients.
In view of the enormous propulsion power to install the idea is to dispense with a reserve. A
simulation showed that the effect of this saving is not significant. For a line like the new built
one from Stuttgart to Ulm there are some sections with 25‰ gradient. Considering a quite
low slack time percentage of 3% the journey between the two cities would be only 20 seconds
longer. Thus other use cases look similar and it can be stated that a design without a traction
force reserve is acceptable.

4.2 Demand analysis for the reference line Paris-Vienna

To gather information about the effect on passenger demand of increased travel speed, the
NGT reference line from Paris to Vienna is chosen for analysis. An operational concept for this
line for 400 km/h was developed at an earlier stage of the NGT project [33]. The model is
reused and modified for the following speed levels: 300, 400, 500 and 600 km/h. The passenger
demand model is based on the European rail network. It includes almost all cities with 50 000
inhabitants and more. These are 1900 cities with 237 Mio inhabitants in countries totaling
525 Mio inhabitants. 120 000 kilometers of rail lines (50% of the real network) are used by
2000 routes with an accurate modelling of travel times and stops. Statistical data for the
calibration originates from Eurostat [34]. It has accuracy on the NUTS-2 level. These are smaller
countries in Germany or regions in France. Additional data from the UIC statistics was used
to complement and verify the Eurostat values [35]. The model is used with four operational
scenarios corresponding to the speed levels.

40 360.revista de alta velocidad