Modern trucks record a remarkable amount of information about how they were driven. In many semi-truck cases, that electronic record is the most objective evidence of what happened in the seconds—and hours—before a crash. The problem is that much of it is controlled by the trucking company, and some of it can disappear.
Types of truck evidence
- Engine control module (ECM) / event data. Often called the “black box.” Depending on the engine and settings, it may record speed, throttle, brake application, cruise control, and hard-braking events before a crash.
- Electronic logging device (ELD). Most interstate truck drivers must record their hours of service electronically under 49 CFR Part 395. ELD data shows driving time, on-duty time, and location history that can reveal fatigue or falsified logs.
- Dash cameras. Many fleets use forward-facing and driver-facing cameras that capture the road and the driver’s behavior.
- GPS and telematics. Fleet-management systems track location, speed, and sometimes following distance and lane departures.
- Dispatch communications. Messages and call records between the driver and dispatch can show schedule pressure or distraction.
- Driver qualification file. Licensing, driving history, medical certification, and training records.
- Drug and alcohol testing records, including post-accident tests.
- Inspection and maintenance records. Inspection reports, repair orders, and out-of-service history.
- Shipping documents. Bills of lading, weight tickets, and fuel and toll receipts that can confirm where the driver was and when.
- The truck itself. Brakes, tires, lights, and the rear impact guard can be inspected by qualified engineers before repairs or salvage.
How long carriers must keep records
Federal rules set minimum retention periods, and some are short:
- Hours-of-service records and supporting documents: 6 months (49 CFR 395.8(k)).
- Driver vehicle inspection reports: 3 months (49 CFR 396.11).
- Vehicle inspection, repair, and maintenance records: 1 year where the vehicle is housed, and 6 months after the vehicle leaves the carrier’s control (49 CFR 396.3).
- Driver qualification files: for the length of employment and 3 years after (49 CFR 391.51).
Video and telematics data are often kept for even shorter periods under a fleet’s own settings, and ECM data can be lost if the truck is repaired, returned to service, or salvaged.
Post-accident drug and alcohol testing
Under 49 CFR 382.303, a carrier must test a driver after crashes involving a fatality, and after crashes where the driver receives a citation and someone is injured and treated away from the scene or a vehicle is towed. Alcohol testing generally must happen within 8 hours and drug testing within 32 hours. Whether testing was done—and done on time—can be important evidence.
Preservation letters and Indiana spoliation concerns
A preservation letter (sometimes called a spoliation letter) puts the carrier and its insurer on notice of a claim and asks them to keep specific evidence: ECM downloads, ELD records, video, dispatch messages, maintenance files, and the vehicle itself. Indiana courts can address the destruction of evidence in litigation, but it is far better to keep evidence from being lost in the first place. When necessary, a lawyer can ask a court for an order to protect evidence.
What you can preserve yourself
- Your photos and video of the scene, the truck, and your injuries.
- Your own vehicle and its event data recorder—don’t let it be salvaged until you have advice.
- Dash-cam footage from your car, and names of witnesses who may have their own.
- Your medical records, bills, and a simple daily journal of pain and limitations.
Frequently asked questions
Do all semi-trucks have a black box?
Most modern heavy trucks have an engine control module capable of recording some data, but what is recorded depends on the engine, its settings, and how the event was triggered. A qualified technician usually needs to download it.
How long does a trucking company have to keep ELD data?
Federal rules require carriers to keep hours-of-service records and supporting documents for six months (49 CFR 395.8(k)). Other records have different periods, and some video systems overwrite footage sooner.
What is a spoliation or preservation letter?
It is a written demand that tells a company to preserve specific evidence related to a claim. It helps prevent routine deletion or repair from destroying evidence and supports a later request for relief if evidence is lost.
Can I get the trucking company’s records myself?
Usually not right away. Some information is public, such as a carrier’s FMCSA safety snapshot, but internal records generally are obtained through a claim or the discovery process in a lawsuit.
Sources
- National Highway Traffic Safety Administration (NHTSA), Traffic Safety Facts: Large Trucks, 2024 Data, DOT HS 813 816 (PDF)
- 49 CFR 395.8 — official heading: “Driver's record of duty status.” Drivers must keep a record of duty status (logs), generally on an electronic logging device.
- 49 CFR 396.11 — official heading: “Driver vehicle inspection report(s).” Driver vehicle inspection reports on the vehicle’s condition.
- 49 CFR 396.3 — official heading: “Inspection, repair, and maintenance.” Carriers must systematically inspect, repair, and maintain their vehicles and keep maintenance records.
- 49 CFR 391.51 — official heading: “General requirements for driver qualification files.” The driver qualification file a carrier must keep for each driver.
- 49 CFR 382.303 — official heading: “Post-accident testing.” When a commercial driver must be tested for alcohol and drugs after a crash.
Indiana Code links open the official chapter PDF from the Indiana General Assembly (2026 Code); federal rules link to the current eCFR text.
More official links: Indiana accident resources · Indiana crash statistics · How to get your crash report
General information only—not legal advice. Laws change and every case is different; deadlines can be shorter in some situations. Prior results do not guarantee a similar outcome.