Key Takeaways
The most persuasive evidence in truck accident cases usually comes from the trucking company’s own files: engine control module data, electronic logging device records, inspection reports, driver qualification files, maintenance records, and dispatch documents. Federal rules let carriers discard many of these records within three to six months, and some electronic data can be overwritten once the truck returns to service. A preservation letter and a prompt investigation from Hupy and Abraham puts the carrier on notice and keep that proof available for injury claims in Wisconsin, Illinois, and Iowa.
Most of the proof in a truck crash case never shows up in the police report. It sits in the truck's onboard computer, in the carrier's driver and maintenance files, and in a dispatcher's message history, and the trucking company controls nearly all of it. The truck accident evidence that does the most to prove a claim is usually that paper and digital trail, matched against what investigators find at the crash scene.
At Hupy and Abraham, our experienced truck accident attorneys represent people hurt in semi-truck and commercial vehicle crashes across Wisconsin, Illinois, and Iowa. A large share of our early work on these cases is figuring out which records exist, who holds them, and how long federal rules require the carrier to keep them. Here's what you should know.
Table of Contents
- What Truck Accident Evidence Comes From the Truck Itself?
- What Records Does the Trucking Company Keep About the Driver and the Truck?
- How Does Evidence From the Crash Scene Fit In?
- Why Do Preservation Letters Matter After a Truck Crash?
- What Does a Prompt Investigation Add?
- Talk With a Truck Accident Attorney at Hupy and Abraham
What Truck Accident Evidence Comes From the Truck Itself?
A commercial truck records its own behavior in ways a passenger car usually does not. Two onboard systems tend to carry the most weight.
Engine Control Module (ECM) Data
The ECM, often called the truck's black box, can capture speed, throttle position, brake application, cruise control use, and sudden deceleration events in the moments before impact. If the driver says traffic stopped without warning, but the ECM shows the truck traveling 68 mph with no brake input until a second before the collision, the data usually settles the question. Our team understands how black box data can support a commercial truck claim and how to use that information in litigation.
ECM data is not permanent. Depending on the system, new events can overwrite stored data once the truck is back in service, and properly downloading it requires specialized equipment and a trained technician.
Electronic Logging Device (ELD) Records
Most interstate truck drivers must use an ELD to track driving and on-duty time. Federal hours-of-service rules generally limit property-carrying drivers to 11 hours behind the wheel after 10 consecutive hours off duty, and ELD records show whether a driver stayed within those limits. Logs that do not align with fuel receipts, toll records, or GPS data can indicate fatigue or falsified entries, which is why hours-of-service violations are a common thread in serious truck crash claims.
Under federal recordkeeping rules for driver logs and supporting documents, carriers only have to keep these records for six months.
What Records Does the Trucking Company Keep About the Driver and the Truck?
The Federal Motor Carrier Safety Regulations require carriers to document who they put behind the wheel and how they care for their equipment. Those files often reveal problems that started long before the crash.
Driver Qualification Files
Every motor carrier must keep a qualification file for each driver it employs and retain it for as long as the driver works there, plus three years. These files typically include:
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The driver's employment application and safety history from prior employers
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Motor vehicle records showing past violations and license suspensions
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A road test certificate or a copy of the commercial driver's license
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The driver's medical examiner's certificate
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Annual reviews of the driver's record
A file showing prior crashes, an expired medical certificate, or a skipped background check can support a claim that the carrier was careless in hiring or keeping that driver. That matters because a trucking company can be held liable for its own negligence in hiring and training drivers, not just for the driver's mistakes on the road.
Inspection Reports
Drivers must report defects they find during inspections in writing, and carriers must certify that reported problems were repaired or did not need repair. Roadside inspection reports from state troopers and annual periodic inspections add to the paper trail. These obligations come from the federal inspection, repair, and maintenance standards in Part 396 of the regulations. A defect report for worn brakes from three weeks before a rear-end crash, with no repair certification to back it up, is the kind of document that changes how a case is valued. Driver inspection reports only have to be kept for three months.
Maintenance Records
Carriers must keep a maintenance file for each vehicle they control, tracking inspections, repairs, and scheduled service. Those files must be kept for one year and for six months after the vehicle leaves the carrier's control. Skipped brake adjustments, repeated tire repairs, or deferred work orders can connect a crash to brake and tire failures caused by negligent maintenance, and they may bring a third-party repair shop into the claim.
Dispatch Documents
Dispatch records show how the carrier planned and managed the trip. Federal hours-of-service rules treat several of these as supporting documents the carrier must keep for six months, including:
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Bills of lading and schedules showing the origin, destination, and cargo for each trip
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Dispatch and trip records
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Messages sent through the carrier's fleet management system
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Payroll records and settlement sheets showing how the driver was paid
These records can reveal a delivery window that was legally impossible to meet or a dispatcher pushing a driver to keep moving. A tight schedule does not prove negligence by itself. Paired with the ELD data, though, it can explain why an exhausted driver stayed on the road.
How Does Evidence From the Crash Scene Fit In?
Carrier records tend to explain why a crash happened, while scene evidence shows what happened. Photos, the police report, witness contact information, and dashcam video anchor the timeline. Understanding what evidence to collect at the scene of a truck crash (if they are physically able to do so) is crucial. Investigators then test that information against the truck's electronic data. When the skid marks, vehicle damage, and ECM readings all point in the same direction, the trucking company has far less room to argue.
Why Do Preservation Letters Matter After a Truck Crash?
Federal retention periods are minimums and short. Driver inspection reports can be discarded after three months and logs after six. Wisconsin generally allows three years to file a personal injury lawsuit, while Illinois and Iowa generally allow two, so a carrier can lawfully discard key records long before a filing deadline approaches.
A preservation letter, sometimes called a spoliation letter, changes that. It formally notifies the trucking company, its insurer, and other involved parties that a claim is likely and identifies the specific evidence they must keep, from ECM downloads and ELD logs to the damaged tractor and trailer. Once a company is on notice, destroying that evidence can carry consequences. Depending on the state and the circumstances, courts may impose sanctions or allow a jury to infer that the missing evidence would have hurt the party that destroyed it. Knowing how to stop a trucking company from destroying evidence and why these letters should be tailored to each crash rather than copied from a template is essential.
What Does a Prompt Investigation Add?
A letter protects records in the carrier's hands. It does nothing for evidence that disappears on its own. Skid marks fade, debris gets cleared, and businesses near a crash site often record over surveillance footage within days or weeks. Witnesses move or forget details, and the truck itself may be repaired or sold.
Starting quickly gives investigators a chance to photograph the scene, inspect the vehicles before repairs are made, arrange a proper ECM download, and interview witnesses while their memories are fresh. That early work feeds directly into accident reconstruction in truck crash cases, where reconstructionists combine physical evidence and electronic data to show how the collision unfolded. The claims with the clearest proof of fault are often the ones where the evidence was secured in the first few weeks.
Talk With a Truck Accident Attorney at Hupy and Abraham
The records that prove a truck accident claim disappear on the trucking company's schedule, not yours. Hupy and Abraham represents people hurt in truck crashes throughout Wisconsin, Illinois, and Iowa. Our attorneys can send preservation letters and begin investigating while the ECM data, driver logs, and inspection reports are still available. Call 1-800-800-5678 or reach out online to schedule a free, no-obligation consultation. We answer calls 24 hours a day, so you can talk with us about your crash whenever you're ready.
