Verification and validation for a sub-system, making part of the On-Board Technological System (hereinafter referred to as STB), in regard to a serial head train so that this would be configured in accordance with the safety requirements - CENELEC Standard EN50129 [3 apps] “Railway Applications - Safety related electronic systems for signaling”.

STB Project

SCMT is an electronic safety system aimed to protect the train march, moment by moment, with respect to: the conditions imposed by the signals, the maximum speed allowed by the railway line under normal conditions and in decay, the maximum speed allowed by the rolling stock. The system enables emergency braking in case of exceeding control speed limits. It is “transparent” to the driver that continues working in accordance to the general conduct rules. The system is divided into the SST (Ground Subsystem) and the SSB (On-board subsystem).

The Ground subsystem consists, in its minimal configuration, of an encoder, generally located in the station. The encoder generates a telegram containing the range of information in accordance to the established protocol and basing on the conditions that the safety device provides. This telegram is transferred to a buoy (or BALISE), or to a TRANSPONDER placed on a side track, which is responsible of sending the telegram to the SSB. The set of two or more buoys installed on the railway line and transmitting the same information content, is called an Information Point or IP (duplication or redundancy is used to increase the system availability in case of failure of a single buoy). The buoy, which in almost in all cases is Eurobalise x 1023bit, is "energized" by the passage of the train’s antenna, thus transmitting the coded information.

The on-board subsystem is composed of a cabinet (cubicle) connected with the peripheral organs (pneumatic plate, MMI, RSC sensors, Eurobalise antenna....). The SSB reads the information coming from the ground and from Eurobalise antennas, interfaces with the train control sensors, interfaces with the driver via MMI and the speed indicator, monitors driver’s operations and ensures train’s security by turning on, if necessary, service or emergency braking.

When the Radio, the DIS and the supervisors bodies are added to the SCMT SSB, it is known as the On-Board Technological System (STB).

Input Documents:

• SCMT Wiring;
• Rolling stock Wiring;
• Installation Specifications;
• Procedures for In-Service release;
• Hardware and Software Configurations;
• In-service Procedures Reporting(MIS);
• In-service Test Reporting.

Output Documents:

Safety Case for the specific application
Activities of safety analysis and validation for the STB system generic application are as follows:

• Installation,
• Subsystem Validation,
• Operation and maintenance.

TdS Installation Phase

The phase is considered to be concluded upon undertaking the following controls:

• verification of the existence of installation specifications and procedures;
• verification of the proper installation; definition of the installation constraints impacting on safety or on system availability; verification, through test reports or via wiring diagrams, the coverage of the above;
• check of the electrical installation project - plant layout; check that the SCMT specific application wiring diagram is in accordance with the general application;
• verification of the correct file generation for a specific application - to properly configure the SSB, 4 configuration files are generated. These files are generated by an operator and then are checked by a second operator. It is necessary that the verification, made by the second operator, would be successful;
• verification of the SSB SCMT proper configuration; it is necessary verify, through the operational test reports, that the SSB is configured with the files checked;
• verification of the existence of procedures for the operational release and check for controls positive outcome; verification that MIS reports are successful.

TDS Subsystem Validation Phase

The Subsystem Validation phase is considered concluded upon the proper execution of necessary tests.

TDS Operation and Maintenance Phase

The Operation and Maintenance phases are considered to be concluded upon check of the status of the specific application maintenance manuals.

Application conditions, derived from Hazard and detected on a generic application or on open points identified during previous inspections, should also be checked.

Tools Used

• Microsoft Word
• Microsoft Excel
• Microsoft Access
  

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