Page 153 - 360.revista de Alta Velocidad - Nº 5

Precise and reliable localization as a core of railway automation (Rail 4.0)

The last level of ETCS shall also improve line capacity by making it possible to manage circulations
with moving blocks. ERTMS Level 3 will allow reducing the number of trackside equipment on
the one hand, and the implementation of moving block in order to reduce the train spacing and
then enhance capacity on the other hand.

Mainly driven by economic reasons and thus, acceleration of ERTMS penetration into the
networks, the use of GNSS-based systems and, in particular, their introduction in signalling
systems is seriously investigated today as a positioning opportunity included in ETCS and tested
all around the world. In this context, GNSS is investigated to be the basis for a new embedded
train locator.

The use of GNSS for low cost signalling solution and, in particular, in the highest level of ETCS
(level 3) and the ERTMS Regional operation context, is an issue that has been investigated since
the beginning of the 2000’s [Raymond, 2004]. The concept of “virtual Balises” emerged to
allow this new technology to penetrate the railway operational modes. The virtual Balises are
dematerialized points, recorded in an embedded geographic database as illustrated in figure 2.
These points are basically coordinates of the real (removed) physical Balises. The goal of the
virtual Balise concept is to detect the position of the train when passing over the identified
points by comparing the GNSS-based location of the train with the database. The train delivers
then the same telegram that would have been sent with the use of the physical Balise. As
such, the process could be as transparent as possible for the global system. The virtual Balise
has been investigated in lots of projects since the beginning of the studies such as in RUNE
[Albanese, 2004] or recently in 3InSat [Rispoli, 2013] or ERSAT [Facchinetti, 2015].

Figure 2: Virtual Balise use instead of physical trackside Balise

With several projects, the European Commission, through the successive Framework Programs,
funded research in order to explore and promote the use of global navigation satellite systems
for low cost signalling solutions and, in particular, in the highest level of ETCS (level 3) and the
ERTMS Regional. First projects were APOLO [Filip, 2001], GADEROS [Urech 2002] and LOCOPROL
[Mertens, 2003] but one can mention tens of others in the past decade until the recent Satloc
[Gradinariu, 2017], GaLoROI [Manz, 2014] or 3inSat [Rispoli, 2014] projects. The concept of
“virtual Balises” has been investigated in lots of projects since the beginning of the studies such
as in RUNE [Albanese, 2004] or recently in 3InSat [Rispoli, 2013] or ERSAT [Facchinetti, 2015].
On-going projects are STARS [Gurnik, 2016] and Rhinos [Neri, 2016] focusing respectively on GNSS
signal reception in railway environments and integrity concepts for railways. A complementary
national project was DemoOrt in Germany [Meyer zu Hörste, 2009]
One European operated line embeds a light GNSS solution today. It is a single track line of 150 km
length with a system developed by the University of Applied Sciences Upper Austria (FH OO) and
operated by Stern & Hafferl, respective Salzburg AG. An on-board unit communicates the GNSS-
based train position to the trackside train controller which is responsible for the movement
authority of the train [Stadlmann; 2006]. The system is implemented in SIL2.

International Congress on High-speed Rail: Technologies and Long Term Impacts - Ciudad Real (Spain) - 25th anniversary Madrid-Sevilla corridor 151