3INSAT - Train Integrated Safety Satellite System

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The 3InSat demonstration project will develop, test and verify a new satellite-based subsystem, based on the ASTS ERTMS system, for allowing the SIL 4 train localization function at Signalling System Level by using GNSS data. The proposed solution would be based on the ERTMS standard requirements. The requirements will be driven by the market needs and by the accreditation and certification strategy.

The 3InSat project has the objective to introduce a train monitoring and control system, based on the state of the art European and international regulations, adopting satellite based navigation and telecommunications systems. In such a way, the investments required along the rail tracks and the related maintenance activities will be minimised. This investment reduction will enable efficient and safe operations where today this cannot be sustained.

More specifically the objectives are:

  • On the positioning part, the 3InSat project is aimed at designing and developing Location Detection System (LDS) prototype using GNSS and ERTMS functions with the objective to guarantee the stringent safety requirements of SIL4 at the signalling system level.
  • On the telecommunication part, 3InSat will select and implement an integrated solution based on the combination of SatCom, 2G/3G  systems and TETRA to realize a link between the on board train control system (e.g European Vital Computer EVC) and the ground based infrastructure (e.g the Radio Block Centre RBC). A Mobile Access Router (MAR) prototype will be developed to manage the multiple wireless links on-board.

Furthermore, 3InSat has the objective to verify these solutions along a regional railways line in Sardinia on 1 test train, where an end-to-end signalling solution will be installed (the installation will not interfere with the existing signalling and will not have any impact on the railway safety). 

Modern railway signalling systems play a major role in providing safety networks to prevent accidents due to human errors. Furthermore, railways traffic management improve the utilisation of scarce and expensive resources like the railways infrastructure. One of the major breakthroughs has been the introduction of an interoperable European standard known as European Rail Traffic Management System (ERTMS), which not only allows speed limits to be transmitted to the driver, but can also continuously monitor the driver's response to this information. An on-board computer effectively compares the speed of the train with the maximum permitted speed and automatically applies the train's braking, if the limit is exceeded. The existing implementation of the ERTMS requires significant investments in ground infrastructures (used for both positioning and telecommunication purposes), preventing its wider deployment.

So far, high speed lines and international freight transport lines have been the primary target for these systems, which are implemented using infrastructures deployed along the rail tracks (e.gbalises (electronic beacons), track circuits, cablings, GSM-R network) that are expensive to procure, install and maintain. Such highly expensive have so far prevented the adoption of advanced train traffic management systems in regional and remote railways lines, where traffic level is typically low. Both railways and train operators are interested in the introduction of advanced safety systems along this type of lines, which therefore represents today an untapped market.

A promising way to reduce the costs associated with the implementation and maintenance of ERMTS compatible solutions is to reduce the extent of deployment of the track side infrastructure using SatNav and SatCom to complement or replace the ground-based infrastructure.

3InSat is a project aiming at developing and validating a new satellite-based platform to be integrated into a  ERTMS system.  This satellite supported solution is not yet available on the market because of the very challenging safety requirements (Safety Integrity Level 4 SIL4 requirement) that a railway signalling system shall comply with. 
A validation campaign is planned on a specific Test Site to be carried out in Sardinia on a 50km line.

Users and their needs

  • The Italian railway infrastructure manager (RFI) and the German one (DB Netz) are reference users and partners of the project; they contribute to the user requirements definition, the tests and the demonstration activities.
  • Other reference users is the Australian private mining company Roy Hill which is building a railway line to transport the minerals from the mines to the port and has already awarded a contract to Ansaldo STS. This project is the first in the world that has specified a satellite-based train control system with a SIL4 train localization function at System Level expected to become operational in 2015.Trenitalia test train in Cagliari station

The worldwide potential market for satellite-based train control systems is quite large. The demand is driven by different indicators: the growth of the core signalling market (+6% year), the government directive in the USA and to some extent in Russia, the new private players (the mining sector) and the need to modernise the old and low traffic lines in Europe.

An important market force is the need to deploy new lines in critical areas where the cost of maintenance of the railways is prohibitive (South Africa, Russia, Australia, Brazil). These needs can be fulfilled with the adoption of satellite technologies in order to reduce track-side circuitry and equipment to the largest possible extent.

Service/ system concept

The localisation service will be based on the provisioning of a safety service including the liability obligations versus the service level agreement. The signalling industry is used to design, develop and deliver solutions which have been certified according to the safety requirements. The customer will be responsible for maintaining the EMI environment associated with the system during the commissioning phases.

Concerning the telecommunication component of the train control systems, the system integrator has to procure the dedicated network fully optimised with its train control system. With the exception of some customers who procure and operate the telecommunication network by themselves, such a network is under the responsibility of the system integrator.

Space Added Value

The advent of satellite telecommunication network will inevitably shift the responsibility of the operation towards a service provider while the operation of the satellite localisation represents a new activity/service in the current value chain. Future service providers are expected to offer the localisation services with guaranteed quality of services and for different performance.

Compared to a traditional system, the life cycle cost (LCC) of a satellite-based train control system will be much lower. The market expectations for a LCC reduction are in the range of 20-40% including the costs of the new equipment and the relevant investments. Concerning the telecommunication component, the target LCC reduction compared to ground-based systems (assuming 10 years operations) is 30% to 60% including the amortisation of investments to customize and certify the terminals.

Product Benefits

3InSat solution will contribute to demonstrate how satellite can bring competitive advantage in terms of costs for the deployment of high safety standard for local/regional lines and lines where is important to minimize the deployment of  the track-side equipment and telecommunications infrastructures. This cost reduction shall anyhow assure high safety standard at the same level as conventional systems based on balises and ground deployed equipment. Additionally, it could help to increase the network capacity and efficiency, by allowing future implementation of short virtual blocks to reduce the train separation in the high traffic nodes.

3InSat project will also address issues related to the integration of the Augmentation data and the Virtual Balise concept into ERTMS functions; the identified integration solutions will be used by ASTS as starting points for proposing the evolution of ERTMS specifications.

The 3InSat project is strategic  to create a synergy between the rail and space technology to build-up a signalling system, based on the ERTMS standard and the GNSS & SatCom technologies.  Such potential enormous benefits will be transferred to the train operators and railways infrastructure managers and in general to the citizens.

For the railways industrial side the expected returns are mainly on the provisioning of a cheaper  ERTMS based train control system solution,  and for the satellite industry the delivery of new applications based on GNSS and SatCom .

In this context, SatCom networks can provide interesting alternative solutions to complement/replace the GSM-R technology that will be phased out in the next years for the obsolescence of the technology and the imminent introduction of the IP based standards.

Product Features

SatCom + SatNav antennaTelecommunication module3InSat project will design, develop, and test specific solutions able to be employed for Safety of Life applications in the railway environment.

SIL-4 train localisation at signalling system level shall be developed in accordance with the CENELEC norms and the tolerable hazard rate (THR) for train GNSS Location Determination System (LDS) shall be derived by means of the hazard analysis and risk assessment for ETCS Level 2 applications (through the reference of the ETCS Class 1 documents). This analysis will be reviewed by an assessor.

The 3InSAT project will include the following  four main developments:

  1. The GNSS simulator to analyse achievable performance under different conditions (e.g. rail network topology, head-ends, confidence errors, environment). The overall architecture of the simulator is composed of the three main parts representing the whole GNSS-LDS System:
    • RS - Reference Stations;
    • TALS - Track Area LDS Safety server;
    • OBU - On Board Unit.
    • GNSS-LDS simulator can work either with real data or with simulated data.
  2. The LDS  system integrated with ERTMS functions will provide a SIL4 compliant positioning solution at the Signalling System Level, through association of different SatNav receivers and on-board information (odometer). The LDS will make use of a proprietary Augmentation and Integrity Monitoring  network able to guarantee the required level of accuracy and integrity. The On Board LDS will have independent integrity monitoring on-board capability to further mitigate GNSS errors.
  3. Bearer-independent IP based Telecommunication Network, which will combine mobile satellite services(B-GAN)with terrestrial solution (2G/3G) to guarantee the necessary coverage and Quality of Service  in relation to the overall system requirements, and compatibility with the existing on board train control system interfaces. A Mobile Access Router prototype to manage multiple wireless links at the same time will be developed.
  4. A Prototype Track Area Augmentation and Integrity Monitoring Network to be installed along the railways track.  

As illustrated by the block diagram below the project adopts a modular architecture with the possibility to implement and deploy individual blocks according to the market evolution. The functions are distributed among the following elements:

  1. Space  segment (GNSS + SATCOM)
  2. Augmentation and Integrity Monitoring  Network
  3. On board unit Localization Determination System (OBU LDS) + Hybrid (satellite and terrestrial) telecommunication module + MAR)
  4. Radio Block Center and ERTMS European Vital Computer

The primary task of the space segment is to provide the reference satellite signals needed for train position computation as well as to distribute real time corrections related to satellite ephemerides, clock offsets, propagation delays, and Signal In Space (SIS) integrity.

The (Track Area) Augmentation and Integrity Monitoring Network plays a role similar to the EGNOS Range and Integrity Monitoring subsystem.

The OBU LDS computes the train position to provide virtual balises by using (a) the local GNSS signal, (b) the augmentation information for integrity monitoring, (c) the digital track map stored on board, and (d) the SIL 4 odometer data. The on board bearer-independent telecommunication subsystem will take care of ETCS messages and other important system information through the use of the MAR. 

Figure 1. Reference Architecture


Key Issues

The main challenges of the project are related to the GNSS based LDS design and development, integrated with ERTMS functions, because of the stringent SIL4 requirement at Signalling System Level.

The Track Area Augmentation and Integrity Monitoring Network represents another challenge since its performance in terms of availability will contribute to the fulfilment of the SIL4 requirement.

Last but not least, bearer-independent Telecommunication Network shall demonstrate a good trade-off between performances and costs which can guarantee a sustainable a competitive service of the 3InSat solution.

The signalling solution shall be fully certifiable and it shall demonstrate its economic and non-economic viability

Current Status

System Deployment Acceptance (SDA) was successfully concluded for the Localization Determination System (LDS) and the terrestrial (Vodafone M2M) and the satellite (Inmarsat Broadband Global Area Network (BGAN)) telecommunications subsystems.

In 2014, the TLC Test Campaign (both terrestrial and satellite) was executed on the Cagliari-Olbia line in Sardinia. The EURORADIO over IP protocol was tested on both solutions. A TLC networks performance analysis was conducted showing the performances of the network are compliant with the requirements expressed for low traffic lines. The proprietary augmentation network  and the installations on board of the train have been concluded.

Currently, a passenger train equipped with the On Board LDS (operating in shadow mode) is running along the railway line.  

A  demonstration campaign of the integrated solution is expected to take place in Sardinia in Q1 2015. In Q3 2015 a complete and certifiable signalling solution will be deployed and tested again in Sardinia making use of the GNSS based LDS and the Satcom+2G/3G+TETRA+MAR 

Prime Contractor

Ansaldo STS


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A.D Praha
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Czech Republic
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Rete Ferroviaria Italiana
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DB Netz
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Project Managers

Contractor Project Manager

Gianluigi Fontana
Via Paolo Mantovani 3-5
16151 Genoa GE
+39 010 655 2079

ESA Project Manager

Michele Castorina
Keplerlaan 1
2201 AZ Noordwijk

Status Date

09 March 2015 - Created: 15 February 2014