Research
Brief
Development of a strategy on train positioning
T990 - August 2014
Background
This research was commissioned to consider whether the
adoption of an industry strategy on train position, based on a
common train location service (TLS), would bring the industry
better value for money than allowing market-led solutions to
emerge. This project forms part of a wider initiative by RSSB to
assess the potential value and impact of emerging positioning
technologies on the railway. This research has been carried out
on behalf of the Future Communications and Positioning Systems
Advisory Group, (FC&PS AG), which reports to the Vehicle/Train
Control and Communications System Interface Committee,
(V/TC&C SIC).
Figure 1 - Positioning strategy: the end game?
The TLS concept is for a system which combines location data
from any available sources and makes it available, together with
quality parameters, to any applications needing positional
information. The concept is independent of locator technology
and of the applications making use of location data and therefore
embraces new technologies and survives their obsolescence. It
spans on-board and infrastructure-based elements, inputs, and
applications.
RSSB R&D Programme
Block 2 Angel Square
1 Torrens Street
London EC1V 1NY
enquirydesk@rssb.co.uk
www.rssb.co.uk/research-developmentand-innovation/research-and-development
1
Development of a strategy on train positioning
T990 - August 2014
Figure 2 - The Train Location Service
The research concluded that there is a positive industry value for
money case for the TLS; that a simple initial TLS implementation
is deliverable within a 3 to 5 year time frame, and it has proposed
an implementation strategy.
The research also concluded that the TLS concept is consistent
with other industry work streams:
 COMPASS - COMbined Performance And Safety System led by Network Rail
 ETCS - European Train Control System led by the industry
ERTMS - European Rail Traffic Management System
programme
 TM - Traffic Management led by Network Rail, and
 NCIS - National Customer Information Strategy led by
ATOC - Association of Train Operating Companies
More detailed work is needed to develop a full picture of the future
relationship between them.
Aims
The aims of the research were:
 The development of a high-level concept of operations and
functional specification for the TLS.
 Analysis of the value for money which might be expected
from investment in a TLS, based on the benefits available
via an agreed set of applications.
 Analysis of the supply chain capability to deliver the
proposed functionality in the proposed time frame.
Findings
2
RSSB
The value for money study concluded that the TLS has a benefit
net present value (NPV) over 15 years of approximately £70m for
a capital expenditure of £10m, based on the evaluation of a small
set of applications using conservative assumptions. This benefit
is compared with a base case which assumes how the 'as now'
approach would develop without a TLS.
The value for money (VfM) benefits identified were:
 For Network Rail, that positioning data with consistent
accuracy would be available for applications such as delay
attribution.
 For train operators, that track-specific information would be
systematically made available on board the train, for
applications such as selective door operation, driver
advisory and driver support systems, without the need to fit
new application-specific equipment on the infrastructure.
 For passengers, that better predictions of train movement
through the network would be available on board the train.
The TLS business case has taken a very conservative view on the
basis of other applications not directly taken into account during
the research, (including approximately a further 40 that were
identified by RSSB project T892 - Data and analysis for a costeffective GPS-based locator with simple augmentations). This
could be further improved through consideration of emerging ontrain positioning devices, with significantly better capabilities than
simple GPS, combined with architectures which enable such
devices to be shared between multiple applications.
A TLS could therefore enable a cost-effective development of
new applications, and retro-fitting to rolling stock to support
specific applications, could further bring forward the benefits.
TLS also has the potential to further enhance the benefits of other
initiatives such as COMPASS and Traffic Management, through
complementing the work in these areas and to encourage train
operators to fit and use on-board equipment.
The supply chain review ascertained that a simple TLS
implementation is feasible now, using current technology, and is
capable of being rolled out within 3 to 5 years.
The research recognised that ATOC's National Customer
Information Strategy (NCIS) and Network Rail's Traffic
Management and COMPASS projects share some objectives and
technical architectures with each other and with TLS, in respect
of the capture and distribution of location information.
It also recognised that the TLS concept could continue to add
value in the European Rail Traffic Management System/
European Train Control System (ERTMS/ETCS) railway. The
envisaged TLS architecture can handle ETCS information without
RSSB
3
Development of a strategy on train positioning
T990 - August 2014
change. However, the balance of TLS benefits and the way in
which TLS fits into the railway system will change when ETCS
Level 3 is rolled out and train location no longer relies on trackside
equipment such as track circuits or axle counters. This will give
more emphasis to the advantages of diversity and less to
providing known accuracy and track discrimination, which ETCS
inherently provides.
The research also developed a route map which proposes a
model for TLS ownership. This suggests that it would be
beneficial for Network Rail to own the fixed multi-train tracking
database (TLS-MT) and to provide access to the data for rolling
stock owners and operators on an information sharing basis,
because of its ownership of the current train tracking system.
Rolling stock owners would own the on-board equipment. The
relationship between owners and operators needs further
consideration, but in principle, owners and operators who provide
information from their trains would be entitled to draw information
out. Third parties could be provided with access to information on
a subscription or pay-as-you-go basis.
Deliverables
The reports delivered as part of this research can be obtained
from SPARK (www.sparkrail.org):
 Executive summary - An overview of the research, its
findings and recommendations.
 Concept of operations and system architectures - This
envisages the creation of an integrated train location
service (TLS) as the single source of train location
information. The architectures have been developed to
cover a number of evolutionary stages, taking into account
the plans for the development of the railway.
 Functional specification - provides a brief description of the
train location service and where it fits in to the national
railway system.
 Supply chain analysis - engagement, sourcing strategies,
system costs.
 Value for money study - defining the value for money case
and developing the value for money model.
 Cost structure - costs summary, capital and operational
expenditure.
 VfM model - an Excel-based spreadsheet model.
 Supply chain analysis - details of supplier engagement.
 Supplier survey responses (company confidential, RSSB
staff only).
4
RSSB
Methodology
A set of high level system architectures were developed, to agree
the scope of a TLS.
A representative set of location-dependent applications (from
those listed in project T892) were selected to form a basis for
investigating whether they would benefit from a TLS, and
corresponding order of magnitude train location requirements
were derived for those applications in a series of stakeholder
workshops.
The research adopted the premise that if the TLS concept were to
be realisable in the near future, the implementation had to be
based, in the first instance, on existing systems and technologies.
Thereafter it would need to be capable of integrating other
technologies.
The research then began to develop how a simple integrated TLS
could be created; this was used as the basis for the supply chain
analysis and value for money study.
Train location derived from on-board sensors (such as GPS,
odometry, and inertial measurement) would be integrated in a
TLS on-board unit (TLS-OB) and compared with an electronic
track map. The output should be accurate to within better than
+/- 10m. Complete coverage could be given by hybridisation of
GPS and other (primarily odometry) inputs. Discrimination
between tracks could also be available if the train carried a Radio
Frequency Identification (RFID) tag or balise reader and where
the relevant section of route was fitted with tags or balises at
every diverging switch and junction. However, adoption of the
TLS concept does not need the infrastructure to be fitted with
these devices. The map matching is a new technology that is still
to be developed.
TLS-OB will communicate with the infrastructure through a mobile
communications gateway, with which most trains are now being
fitted. The existing 2G and 3G public mobile data networks will be
used initially. Upgrading to LTE (4G), once this is overlaid on the
Global System for Mobile Communications - Rail (GSM-R)
infrastructure, will improve the performance of the system.
On the infrastructure, information from existing track-based train
detection, plus auxiliary detection as implemented by COMPASS
and other projects, would be integrated in a TLS multi-train
tracking database (TLS-MT). TLS-MT would also receive tracking
information from TLS-OB units on trains and would integrate this
with the infrastructure information to give a 'best fix' available at
RSSB
5
Development of a strategy on train positioning
T990 - August 2014
any time, including both location along the track (derived from the
train) and track discrimination (derived from the infrastructure).
This information would also be fed back to the train, together with
quality parameters, enabling applications to determine whether
the location estimate is appropriate to use.
The TLS-OB on any specific train would have fresh information
from its on-board sensors, plus enhanced (but less up-to-date)
information returned from TLS-MT. It would therefore have a track
specific location estimate. Potential uncertainty introduced by
diverging junctions would be acknowledged, or mitigated by on
board sensors if available, or algorithms interpreting 'planned
path' information which will ultimately be updated in real time by
the traffic management system.
The TLS-MT functionality could be implemented independently,
or integrated into Network Rail's planned Traffic Management
System.
The TLS-OB functionality could be implemented in a stand-alone
hardware unit, or as a software upgrade for trains which already
carry a suitable train management system.
Next Steps
Carried out on behalf of the FC&PS AG, and V/TC&C SIC with
support from the Driver Advisory System Board, much thought
has been given to developing the next steps for taking this work
forwards.
To date, it has been agreed that this should progress within the
context of being able to ascertain how TLS would build on
features shared with ATOC's NCIS and COMPASS, to deliver
benefits beyond those planned for these systems. Four areas of
further research in support of the TLS concept are proposed:
 Accuracy - Understanding the parameters of the
applications, existing systems, technology mix and integrity
levels. Looking at the requirements for traffic management,
high integrity, ERTMS level 3.
 Message Protocol - Understanding the message content
and integrity requirements for sources of information and
the technology mix across infrastructure and rolling stock, to
develop an improved understanding of the interface and
architectural design.
 Infrastructure mapping - investigating improved map
designs and co-ordinate systems for the railway.
 Data Ownership and Sharing - developing a business model
and improving understanding in the areas of data
6
RSSB
management, data flow, data storage and information update.
It is proposed that this work should be followed by the
development of a demonstrator, possibly along the lines of the
COMPASS model office to encourage supplier and train
operating company interest in the TLS concept. This is thought to
be needed to help establish a 'route to market'.
The Technical Strategy Leadership Group - Core Group has been
briefed on these next steps and has sought a more detailed
proposal for further work and other activity on track positioning
before making a recommendation to the Rail Delivery Group.
Contact
For more information please contact:
Head of Engineering Research
R&D Programme
RSSB
enquirydesk@rssb.co.uk
RSSB
7