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The key element for improving that situation seems to be a greater degree
of standardization in particular for the ETCS onboard equipment on various
levels: Hardware, software, methods and tools. Standardization by applying
open source licensing concepts will be the focus of this paper.
1.1
From National Diversity to European Standard
Looking back into history of signaling and automatic train protection (ATP)
for mainline railways systems, in the past 40 years a major change in tech-
nology has taken place. In the early days of ATP almost all functions were
implemented in hardware, starting with pure mechanical systems, advancing
to electromechanical components and later on using solid state electronics,
like gates, amplifiers, and other discrete components. Software was not an is-
sue then. Beginning in the late 1970 years an increasing number of functions
were shifted into software, executed by so called micro computers. Today the
actual functions of such devices are almost entirely determined by software.
The dramatic performance increase of microcomputers in the past 30 years
on the one hand and rising demand for more functionality on the other hand,
has caused a significant increase in complexity of those “embedded control
systems” - how such devices are usually called. Furthermore, the development
from purely “monitoring” safety protection systems, like the German INDUSI
(later called PZB: “Punktförmige Zug-Beeinflussung”) or similar systems in
other European countries, which only monitor speed at certain critical points
and eventually stop the train, if the driver has missed a halt signal or has
exceeded a safe speed level, to a more or less (semi) Automatic Train Con-
trol (ATC) systems like the German continuous train control system, called
LZB (“Linien-Zug-Beeinflussung”), which has increasingly shifted safety re-
sponsibility from the infrastructure into the vehicle control units. Displaying
signal commands inside the vehicle on certain computer screens, so called
“cab signaling”, has resulted in greater independence from adverse weather
conditions.
In all over Europe there are more than 20 different mostly not compatible
signaling and train protection systems in use (figure 1). For internationally
operating high speed passenger trains or cargo locomotives up to 7 different
sets of equipment have been installed, just to operate in three or four coun-
tries. Since each of those systems have their own “antennas” to sense signals
coming from the way-side and their own data processing units and display
interfaces, space limitations are making it simply impossible to equip a loco-
motive for operation in all EU railway networks, not to mention prohibitive
cost figures for such equipment. Furthermore, some of the systems are in use
for more than 70 years and may not meet today's expected safety level. Some
are reaching their useful end of life causing obsolescence problems.
For a unified European rail system it is very costly to maintain this di-
versity of signaling systems forever and therefore the European Commission
has set new rules by so called “Technical Specifications for Interoperability”
(TSI) with the goal to implement a unified “European Train Control System”,
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