Truck Black Box and ELD Data
Most trucks record data that can prove what happened in a crash. The electronic logging device records driving hours and location, and the engine control module can record speed, braking and throttle before a hard stop or crash. This data can be overwritten or lost, so it must be preserved quickly.
What data does a truck record?
- ELD: driving time, on-duty status, engine hours and location at intervals (49 CFR Part 395, Subpart B).
- Engine control module (ECM): speed, braking, throttle and cruise control, often captured around hard-braking or crash events.
- Telematics and GPS: speed and route history, often stored by the fleet's provider.
- Cameras: forward-facing and driver-facing dashcams used by many fleets.
How long is truck data kept?
Carriers must keep hours-of-service records and supporting documents for six months (49 CFR 395.8(k)). ECM event data can be overwritten by later events or lost when the truck is repaired, and dashcam and telematics systems often delete footage on a rolling basis. Waiting even a few weeks can mean losing the best evidence.
How do you preserve black box data?
A preservation (spoliation) letter should be sent to the carrier promptly, identifying the truck and the data to keep. An independent expert should download the ECM data using proper tools. If the carrier destroys evidence after being put on notice, courts can impose sanctions.
Frequently asked questions
Do semi trucks have black boxes?
Most do. The engine control module can record speed, braking and throttle data, and electronic logging devices record driving hours and location.
How long does a truck keep black box data?
It varies. Hours-of-service records must be kept for six months, but engine event data and camera footage can be overwritten much sooner.
Who owns the truck's data?
Generally the carrier or vehicle owner. Injured people can obtain it through a preservation letter and the legal process in a claim.
Can black box data prove the truck was speeding?
Often, yes. ECM and telematics data can show speed and braking in the seconds before a crash.
What happens if the trucking company deletes the data?
If it destroys evidence after knowing about a potential claim, a court can penalize it, for example by instructing the jury to assume the data would have hurt the carrier.