Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
IEC 62625-1: Railway Electronics — On-Board Driving Data Recording System (ODDRS)
Understanding the requirements for railway vehicle black box systems under IEC 62625-1
Introduction to On-Board Driving Data Recording Systems
IEC 62625-1 defines the requirements for On-Board Driving Data Recording Systems (ODDRS) in railway vehicles — the “black box” for trains. Much like flight data recorders in aviation, ODDRS units continuously capture train operational data including speed, location, driver commands, and safety system interventions. This data is stored on protected non-volatile media that must survive severe accident conditions including fire, impact, penetration, static crush, fluid immersion, hydrostatic pressure, and electromagnetic fields. The standard establishes a unified framework for railway data recording across different train types, from high-speed rail and conventional trains to metro and tram systems, ensuring that accident investigators have access to reliable operational data regardless of the severity of the incident.
The standard is part of the broader IEC 62625 series and addresses the functional requirements, performance specifications, environmental resilience, and data integrity measures necessary for a robust railway event recording system. For accident investigation authorities, train operating companies, and railway equipment manufacturers, IEC 62625-1 provides the essential technical foundation for implementing compliant and interoperable driving data recorders. The standard draws on extensive experience from existing national systems such as Germany’s PZB/LZB, the UK’s TPWS, Italy’s SCMT, and China’s LKJ, harmonizing these diverse approaches into a single international framework that supports cross-border railway operations.
Unlike aviation black boxes that are typically installed in the tail section, railway ODDRS units may be positioned in the leading or trailing cars of a consist. Installation location directly affects the required protection level — a center-of-consist location experiences lower crash forces than end-of-train positions, enabling column B protection parameters versus the more stringent column A.
Functional Requirements and Data Recording
The ODDRS must continuously record a minimum set of operational data whenever in recording mode. This includes time and date (with 1-second resolution), train speed (2.5 km/h increments below 50 km/h, 5 km/h above), train location (1-meter resolution via GPS or odometry), driver commands (brake applications, traction controller position), and safety system interventions (ATP emergency brake, warning system responses). The system must maintain at least 8 days of continuous recording without overwriting, with the most recent 24 hours held on a removable protected storage medium. The protected storage medium must be orange colored (RAL 2003) for easy identification at accident scenes, and must be removable with tools for forensic analysis.
| Recorded Data | Data Type | Resolution | Recording Trigger |
|---|---|---|---|
| Date and Time | Continuous | 1 s | Entering recording mode or hourly |
| Train Speed | Continuous | 1 km/h | Every 2.5 km/h (<50) or 5 km/h (>50) change |
| Travelled Distance | Continuous | 1 m | Every 1000 m variation |
| Brake Pipe Pressure | Continuous | 1 kPa | Threshold crossings (release/applied/emergency) |
| Cabs Activated | Discrete | N/A | Every change |
| Safety System Interventions | Discrete | N/A | Every change |
| Traction Controller Position | Discrete | N/A | Every change |
The standard requires that the system shall not overwrite data for at least 8 days after recording. However, the protected storage medium for the last 24 hours must be removable with tools, survive specified accident conditions, and retain data for at least 2 years. Designers must carefully balance storage capacity, power consumption, and physical resilience in the memory subsystem.
Protection Capability and Survivability Requirements
The survivability requirements for the protected storage medium are defined through six parameter types with two protection levels (A and B) for each. Column A represents the recommended universal protection level, while Column B provides alternative less stringent requirements. The fire protection test, for example, requires survival at 650 °C for 30 minutes followed by 300 °C for 60 minutes (Column A). The impact shock test specifies 55 g peak, 100 ms duration half-sine pulses along three axes. These requirements ensure that recorded data survives the most severe credible accident scenarios, enabling investigators to reconstruct events leading to railway incidents. The standard also specifies penetration resistance (23 kg weight with 6.4 mm steel pin dropped from 1.5 m), static crush (110 kN for 5 minutes), and fluid immersion (diesel fuel, salt water, and lubricating oil for 48 hours).
From a system architecture perspective, separating the protected storage medium from the main ODDRS processing unit provides significant design flexibility. The storage medium can be independently ruggedized to meet the survivability parameters in Table 1, while the main unit with less stringent mechanical requirements can focus on processing power, connectivity, and data management capabilities. This modular approach also simplifies maintenance and data retrieval operations.
Recording Performance Classes and Data Integrity
IEC 62625-1 defines two recording performance classes: Class R1 requires incoming event data to be recorded within 500 ms, and Class R2 allows up to 3 seconds for improved storage medium lifetime. Both classes assume a data flow of 10 events per second. The standard mandates error-detecting codes on recorded data, access control mechanisms to prevent unauthorized modification, and self-test diagnostics during initialization. The mean time between failures for an ODDRS unit must exceed 50,000 hours, with replacement and restoration possible within 1 hour. Data integrity is further protected by requirements for non-tampering physical security, digital signatures for optional driver identification, and secure data extraction protocols that prevent corruption of the original recorded data during download operations.
Q1: How does the ODDRS standard differ from aviation flight data recorder requirements?
Railway ODDRS shares the same fundamental concept but differs significantly in specific parameters. Railway crash environments involve different mechanical shock profiles (lower g but longer duration), immersion may involve diesel fuel and lubricating oils rather than just salt water, and fire exposure includes longer duration at lower temperatures compared to aviation requirements.
Railway ODDRS shares the same fundamental concept but differs significantly in specific parameters. Railway crash environments involve different mechanical shock profiles (lower g but longer duration), immersion may involve diesel fuel and lubricating oils rather than just salt water, and fire exposure includes longer duration at lower temperatures compared to aviation requirements.
Q2: Can multiple ODDRS units be installed on a single train consist?
Yes. Multiple ODDR units can be distributed across a consist — typically one in the leading car and another in the last trailing car. This provides redundancy and ensures at least one survivable unit regardless of impact location. Each unit’s protection level may differ based on its installed position.
Yes. Multiple ODDR units can be distributed across a consist — typically one in the leading car and another in the last trailing car. This provides redundancy and ensures at least one survivable unit regardless of impact location. Each unit’s protection level may differ based on its installed position.
Q3: What data format is required for recorded information?
Manufacturers must provide a software tool that converts extracted data into standard formats (CSV or XML) for analysis. The standard does not mandate a specific internal recording format, allowing manufacturers flexibility in implementation while ensuring interoperability through the required conversion tools.
Manufacturers must provide a software tool that converts extracted data into standard formats (CSV or XML) for analysis. The standard does not mandate a specific internal recording format, allowing manufacturers flexibility in implementation while ensuring interoperability through the required conversion tools.
Q4: How is driver identification handled in ODDRS?
Driver identification is an optional function that can be implemented via smart cards, asymmetric key encryption, biometric means, or equivalent technologies. When implemented, it enables management functions such as train operation enabling and supports digital signature of recorded data for chain-of-custody verification.
Driver identification is an optional function that can be implemented via smart cards, asymmetric key encryption, biometric means, or equivalent technologies. When implemented, it enables management functions such as train operation enabling and supports digital signature of recorded data for chain-of-custody verification.
