Open Common Log Data Format

Open Common Log Data Format

C-MobILE uses an open common log data format for Cooperative, Connected and Automated Mobility. The specification is open in the sense that it is publicly available on In the frame of the C-MobILE project the version 0.7.10 has been used. The specification is common in the sense that it is developed and shared with many partners, and reused and extended over other deployment projects.

The objectives of the specification are to:

  • Support and scope the logging for verification, validation and evaluation phases
  • Reuse of toolsets for data logging, management and analysis in successive projects
  • Use and share open tools and standards
  • Flexibility to select standard data and file formats in specific projects

The specification separates the specifications of structure, parameter definition, encoding, data formats and file formats. To ensure maximum interoperability, the following messages standardised by ETSI are used.

C-MobILE Message Types


ETSI EN 302 637-2

Cooperative Awareness Message


ETSI EN 302 637-3

Decentralized Environmental Notification


ETSI TS 102 894-2

Common Data Dictionary for all messages


ETSI TS 103 301

ETSI header including version for TS 19091


ISO/TS 19091

Based on SAE J2735


ISO/TS 19321

Dictionary of in-vehicle information (IVI) data structures

Road Sign codes

ISO/DIS 14823

Road sign codes for IVI


ETSI TS 103 097

Security envelope and certificate format


Log data is structured by the sources that generate the data in multiple dimensions, i.e. sensors and  devices, and system architecture layers. The structure separates communication, sensing, vehicle dynamics and functions, application layers and Human Machine Interface (HMI) devices.  A complex in-vehicle system for example using on-board device(s) with cellular 4G/5G, C-V2X and/or ITS-G5 communication technologies can log the same messages separately. The vehicle also logs data from application device(s) and the HMI devices.

Applications and HMIs are vendor specific. Yet they share the logic of services and use case, including trigger conditions, state transitions, events, actions to support drivers (visual, audio) or automated driving functions. The HMI are also vendor specific but also share the logic for triggering the presentation (visual, audio,..) of warnings and information, traffic signs and other symbols.

The above figure shows the layers for a cooperative and automated vehicle system. For personal information devices only the communication, application and HMI layers are relevant, while for road side units the communication and application layers are most relevant. Collecting log data from these different devices in the same format enables the standardisation and automation of data analysis.

Formats for storing log data are limited to standard encoding and file formats (e.g. upper, zip, csv, json, xml). This enables the (re)use of standard tools and existing tools developed for collecting, storing and processing log data. It also enables to convert data from different deployment sites and partner teams into a centralised server.

This approach provides the flexibility to tune the levels of logging to the needs of projects and tests. The structure of the log data supports the scoping and scaling of log data for project phases:

  • Testing and verification: the most detailed logging from all layers are collected to analyse and verify the consistency, performance and interoperability of all system layers and components.
  • Validation: detailed logging to validate the correctness of application decisions and HMI presentations for all events from road side units and back-end servers.
  • Evaluation: reduce the levels of logging to HMI or highest application layers, such as events on the HMI to evaluate road user behaviour, events from traffic management and control systems for the evaluation of traffic efficiency and safety, or events from automated vehicle systems for the evaluation of CCAM.

The major contributions made by C-MobILE to the common log format specifications in version 0.7.10 are the detailed HMI events and the C-MobILE services beyond the standard Day1 C-ITS services.