ROAT Observatory / Topics and terms
What is recorded in a crash?
EDR (event data recorder) and DSSAD (data storage system for automated driving) answer different questions: how the vehicle behaved and which events occurred between ALKS (automated lane keeping system) and the driver.
Jozef Andraško
EDR: what happened to the vehicle
EDR records dynamic, time-series vehicle data just before an event or during a crash for subsequent retrieval. The definition gives vehicle speed before the event and change in velocity during the crash as examples. Audio and video are excluded from this definition.
This does not mean the vehicle cannot have other recording systems. R160 may also cover assistance-system status; the specific scope depends on the applicable version and conditions of the Regulation.
R160, 01-series base (2021/58), paragraph 2.11; Supplement 1 (2022/26).
DSSAD: what happened between ALKS and the driver
Under R157, DSSAD enables determination of interactions between the Automated Lane Keeping System (ALKS) and the driver. Recorded occurrences include, for example, ALKS activation and deactivation, a transition demand, engagement of a minimum risk manoeuvre and an EDR trigger input.
The corresponding occurrence flag, reason where appropriate, date and timestamp are recorded. These are requirements for ALKS under R157; they cannot automatically be extended to every automated driving system.
R157, 01-series base (2022/59/Rev.1), paragraphs 2.15, 8.1, 8.2.1(a)–(c), (g), (i) and 8.3.1.
Illustrative case: a transition demand followed by a crash
Consider a vehicle equipped with EDR and ALKS with DSSAD. The system issues a transition demand and a crash occurs later. EDR may help reconstruct vehicle dynamics; DSSAD allows examination of whether and when the demand, deactivation or another occurrence was recorded.
A combined assessment requires checking what the data mean, their timing, the system version and the completeness of available records. Recording a transition demand does not by itself establish whether the driver had a realistic opportunity to intervene effectively.
Author’s illustrative case and interpretation, drawing on R160 paragraph 2.11 and R157 paragraphs 8.2–8.3.
Software version and joint data retrieval
Paragraph 8.3.2 of R157 requires the relevant ALKS software version to be clearly identifiable for a recorded occurrence. Paragraph 8.5.1 requires adequate protection of stored data against manipulation.
Paragraphs 8.4.5.1–8.4.5.3 govern joint retrieval of selected DSSAD and EDR data under specified conditions, including occurrences preceding the EDR trigger. This is not a general requirement to record the entire journey continuously or an automatic right of access for everyone.
R157 · ECE/TRANS/WP.29/2022/59/Rev.1 · 8.3.2; 8.4.5.1–8.4.5.3; 8.5.1.
A record does not decide liability
Technical data help establish the sequence of events. Legal assessment must also identify the applicable duties, the circumstances of compliance or breach, and the connection with the outcome. EDR and DSSAD therefore complement other evidence.
Access and retention cannot simply be assumed either. R157 leaves data access, privacy and availability to national or regional law. When storage is full, it permits overwriting the oldest data while respecting data-availability requirements.
Author’s interpretation of evidentiary significance; R157 paragraphs 8.1, 8.4.1 and 8.4.2.