electrification focus
Margo van Vliet, Consultant Rail Simulations, ARCADIS Nederland BV
Bas Bollinger, Business Development Director Rail, ARCADIS NV
Traction Power Simulations
Power supply is a key factor for reliable assumptions within the simulation, and the train service. Any design, whether
train operations and therefore an essential fidelity and validity of the simulation extending on existing infrastructure or
part of the electrified rail infrastructure. At outcomes. starting from scratch, will first need to
the same time it is a major investment to A proper simulation will either abstract focus on the transport functionality before
have it well implemented or adapted to the complex railway process in such a way looking at the system functionality of the
increasing requirements. It looks obvious, that the research question can be design question. Or to be more specific,
but in reality it is quite complex to find answered while not doing the irrelevant first focus on infrastructure layout and
the optimal system - especially because details injustice. Or the simulation is so requested frequency before detailing it
the functionalities and requirements are comprehensive, that all the elements of with signalling and then power feed.
strongly related to the alignment design, the system are represented and influence Although this order of work will apply to
the signalling and the rolling stock the process, thus allowing a full and any fully-fledged railway simulation
specifications. complete insight into the consequences of model, all references in the examples
And how do you know the estimated any changes. However, in both cases the below are to Xandra, the simulation model
energy consumption is realistic and input of valid source information is developed by ARCADIS.
optimal, related to the envisaged time essential to the results.
table? Good planning, integrated As the reliability and the trust people put Xandra simulation tool
specifications and well-managed design in computer simulations depends on the With Xandra, networks can be modelled,
interfaces are a must in order to achieve validity of the simulation model, thus allowing the analysis of exploitation
an optimised system. verification, validation and sensitivity scenarios and the optimisation of traffic
Simulation is an important feature when analysis are of crucial importance in the flows. Also it permits the integration of
engineering any system that involves development of computer simulations, as modifications to, amongst others, the
many processes. Simulation can thus also well. Furthermore, a simulation model infrastructure, the signalling, the power
have a significant impact on a railway should not provide a different answer for supply, and the rolling stock, which makes
infrastructure design. Nonetheless, even each execution but should be able to it a perfect tool for calculating the effects
simulations require a recommended order reproduce the results. of future improvements to the service in
of work in order to benefit the best results In general, it can be said that different long-term studies.
in the most efficient manner. Key issues phases of the design process are To build a model in Xandra the following
for a good simulation include acquisition characterised by different levels of detail – information is generally required:
of valid source information, selection of solving the traffic demand requires a • The tracks and their track
key characteristics and behaviours, the use higher and more abstract level of analysis characteristics as well as height profile
of simplifying approximations and than ensuring the safety and robustness of and the line's integration in the larger
network.
Current situation • The rolling stock characteristics and
timetables.
• The power supply system and its
characteristics.
• The security and signalling systems.
This simulation tool enables exploitation
studies based on regular delay-free
timetables or a stochastic approach of
delay/traffic interference with timetables
based on Monte Carlo variability. However,
this tool also allows load flow calculations
of the electrical power supply based on
mutual coupling of electrical wires using
ATP-EMTP (EMTP line models using Carson
formulas) with a return feed back on the
mechanical power of the train. Xandra can
combine both direct current (DC) and
alternating current (AC) lines in one
Future situation network simulation.
Signals 242 and
510 were moved, System functionality: Signalling
decreasing the improving capacity
succession times Once the transport functionality can be
between the two fulfilled, system functionality becomes a
trains (the blue factor in railway simulations, whereas
lines) and with laying out the basics of the
resulting in the infrastructure and the timetable, the idea
second train is to squeeze as many trains on as little
arriving earlier at infrastructure as possible.
its destination. The objective of signalling is to create
sufficient time and space around a train to
ensure its safety. Using fixed block
systems (e.g. ERTMS level 1 or 2) will pose
32 | the rail engineer | october 2008
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