Metro Rail News October 2017

The Efficient Speed Control service involves the
application of pre-recorded accelerations to the train
according to its position, optimizing the consumption
pattern. The system will work under the supervision of
the national/ERTMS ATO / ATP (Automatic Train
Operation / Automatic Train Protection) installed on
the train. The command speed will always be less than
the limit set by the ATO / ATP. This system provides a
reduction of pollutant emissions and energy savings of
over 10% in addition to preventing accidents due to
inappropriate speed caused by a combination of
technical failures, human errors or limitations of the
signalling system.
ERTMS 3 solves the track-circuit limitation by
implementing the moving block concept and
minimizing the signalling over the
infrastructure. However, ERTMS 3 is still in
conceptual phase, mainly due to the technical
limitations of positioning trains accurately and
reliably along the route without expensive
track signalling equipments. ERSAT, RHINOS
and STARS H2020 projects or 3INSAT ESA
project try to resolve the on-board train
localization (Location Determination System),
combining on-board sensors (tachometer,
accelerometers and doppler radar
information) with GNSS systems. The paper
Field Experience with GPS based Train Control
System published by the International Union
of Railways (UIC), calculates a residual risk of
higher than 10 -5 /h based on operational
experiences, which is near SIL 1 (Safety
Integrity Level 1) and does not accomplish
what the SIL4 requires for critical signalling
systems. Furthermore, GNSS signals are
vulnerable to interference due to being
extremely weak when received on Earth’s
surface. Therefore, even a low-power
interference signal can easily disrupt the
operation of commercial GNSS receivers
within a range of several kilometers.
ADS provides a disruptive positioning
solution which solves in a reliable, safe,
sustainable and low-cost manner the
geolocation for railway industry.
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