0. System modelling and holistic simulation
Saïd EL FASSI
ERTMS Project Manager
SNCF Engineering
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1. Overview System modelling and holistic simulation :
To optimise the design in interface with existing infrastructure systems
To identify and to confirm performance targets
To optimise cutover plan
To mitigate project risks
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2. Mass transportation in dense railway network
Large cities as Paris, London are facing a significant increase of the transport capacity demand.
Suburban lines are crossing the city. In the core area, the passenger flow is tremendous.
Without extending the existing infrastructure, our challenge is to offer to passengers a significant improvement of the service quality by :
Increasing the transport capacity offer,
Increasing the service regularity,
Increasing the overall availability.
Challenges to improve the service quality in dense area of the existing railway network
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3. Mass transportation in dense railway network
Transport capacity
Journey Time
Regularity
Passenger’s expectations
Constraints
How to answer?
Rules & regulations
Safety
Existing system
Challenges : How to provide the best answer ?
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4. Mass transportation in dense railway network
Railway system
Rolling stock
Interlocking
Trackside
Operation and Maintenance
CBTC
CBTC technology but in an open railway environment?
Handle the complexity without forgetting the final users’ expectations
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5. CBTC in a railway system
Rolling out CBTC technology in a railway system is not just upgrading the signalling sub-system.
The Railway System is an entire complex system consisting of
Trackside Technical Systems
Train sets
Technical interfaces between sub-systems, components
Environment in which the system is operated
Operation rules
Maintenance policies
Human resources
The overall performances of the railway system is achieved by a system wide vision approach.
Introducing CBTC technology in a railway system requires to visit all its components and to govern signalling revamping project through an holistic approach
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6. Handle complexity : Facts
Functional and safety requirements are not anymore confined in a single piece of equipment or subsystem. They are spread off between rolling stock, trackside systems,…
A tight management of the interfaces is required,
The functional allocation makes the interfaces more fuzzy,
Digital systems and distributed architecture require to manage time effects,
Operation and maintenance constraints have to be addressed,
Text-based approach proves a less efficient means of handling such complexity.
Environment
Diversity between rolling stock and trackside principles,
Diversity of signalling systems,
Diversity of geographic configurations,
Diversity of suppliers,
Difficulties to communicate between suppliers and railway experts.
Signalling systems and environment are more and more complex
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7. System performances are achieved through a global system vision
Handle complexity
The signalling system has to be considered in the overall system with all its intricacies
The overall performances of the railway system is achieved by determining the right allocation of performance of each sub- system:
Rolling stock,
Signalling,
Headway,
Dwell time in station,
Global safety : Safe braking model, track conditions,
A global system vision approach has to be developed.
System performances
Global safety
Rolling Stock
Signalling
Traction power
Track
Dwell time
Headway
Availability
System performances are achieved through a global system vision
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8. Requirements Performance allocations
Holistic approach from the definition phase up to the construction phase
Main goals have to be addressed
During the earliest stage of the project
Define performance requirements of main system parameters
Coordinate expert with skills in a wide range of disciplines
Get a clear cut picture of what requires modification
Define functional and technical requirements
During the project execution
Check continuously the system consistency.
Check the cutover program and its performance
Detect at the soonest non compliance
Requirements Performance allocations
Definition phase
What we are expecting
System performances
Construction phase
What we get
Holistic approach for reducing project risks
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9. Holistic approach and system requirements
Our approach is to develop a model-based system design methodology starting from the earliest stage of the project
Determine performance allocation
Build up models of existing signalling system
Build up kinematic model for rolling stock
Build up models of functional requirements
Follow a continuous refinement and improvement of models
Use of models to validate interface specifications
Use of models to proof safety requirements
Connect all models
Connect model based design and Hardware in the Loop
Setup a versatile system integration platform
Check & proof
Refine
Specify
Key to success : Model-based system approach as a collaborative tool with suppliers and partners
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10. Holistic approach and system requirements
Three examples of model based system approach
System performance allocation
Signalling model
System integration platform
Key-success : Model-based system approach as a collaborative tool with suppliers
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11. Performance allocation
Performance allocation thanks to simulation tool allows assessment of :
Sensitivity of the various parameters
Safe braking model parameters
Braking capability
Propulsion capability
Degraded modes
Response times of the different systems
Traffic regulation margins
Energy consumption optimisation
Modes of operation
Final choice is governed by the best balance between
CAPEX
OPEX
Performance achievement
Performance allocation is a key project driver
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12. Signalling Interface management
PRCI Interlocking is a relay based technology
Using such interlocking in the CBTC environment requires some adaptation.
The main goal is to switch from a functional specification to a dynamic model in order to
Make available an interlocking with a real behaviour
Define and check the modification at the interlocking level
Introduce the model in CBTC and system integration platform
Define and check all migration phases of the interlocking
Assess performances of each migration phase
Model of Interlocking provides system assurance
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13. Interlocking environment
MES / TRI
SNCI/SNCO
Interlocking
Trackside equipment
MMI command/control
Adjacent interlocking
Switch
Track Circuit
Signal
Part included in the model
Environment
Point machines
Signals (nominal and degrade modes)a,
Track circuits
Trackside status behaviour
User’s interface : allows to command and to control the interlocking
Adjacent interlocking
Interlocking modelling principles
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14. Interlocking Sample of cabling
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15. Interlocking environment
MMI for trackside components and commands and controls of routes
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16. System integration platform
Models during system design
HIL system integration
Tender specifications
Environment models
Reuse of environment models
Refinement
The integration of the system follows the system development cycle
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17. Global system vision through modelling
Our first lessons
Model-based approach launched in the early phase of the project provides means :
To define more accurately the system and its interfaces
To clarify the behaviour of the system
To locate and to correct non conformance along the design and construction phases and not at the end of the project
To communicate and to share with external partners and to create more efficient supplier relationships.
To get a better vision at project management level
Model-based system approach as a collaborative tool with partners and suppliers
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18. Global system vision through modelling
Our first lessons
Model-based approach increases the efficiency of the project by :
Reducing on site and dynamic testing costs : dynamic testing is focused on the verification of real time constraints,
Giving a clear guide of the project’s testing plan,
Providing a clear vision of the status of the project : the validation of functional requirements in advance of the design phase clears specification’s uncertainties,
Reducing project’s risks and providing a better assurance in project’s risk assessment
Securing the overall project schedule: clearance of technical risks in the early stages of the project procures margins for optimizing the overall schedule.
Model-based system approach increases the efficiency of the project
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19. Thanks for your attention
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