Crash Answers Through Objective Data

The “black box,” referred to by many professionals as an Event Data Recorder (EDR), plays a vital role in commercial motor vehicle accident investigations by utilizing advanced technology to monitor and record data.

The EDR is installed in most commercial trucks to record specific vehicle and occupant information.

It typically includes sensors responsible for detecting and recording various aspects of the truck’s operation, such as speed, throttle position, and brake usage.

In the event of a truck accident, the black box data can be used to determine the root causes (sources of fault) of an accident, analyze the cause, and identify ways to prevent similar incidents in the future.

A truck accident attorney can use this data to build a strong case and advocate for their clients.

The recorded data can often refute claims made by truck drivers, trucking companies, or other parties involved in a truck accident.

The data compiled by a commercial truck’s black box is crucial for monitoring and recording various aspects of the vehicle’s operation, including speed, location, and driver activity.

How Is Black Box Data Accessed?

Trucking companies own and control black box data.

Because of this, access by outside parties may require legal action, such as a subpoena, court order, or preservation letter.

Prompt action is critical, as data can be overwritten or deleted quickly after an incident.

Accessing black box data from devices in commercial trucks is a technical and legal process that involves several key steps and restrictions.

It requires specialized software and equipment, and the process must be handled carefully to ensure data integrity.

Experts must often physically connect to the truck’s ECM/EDR at the accident site or a secure location to download the data before it is overwritten or lost.

Only trained technicians or forensic experts should perform the extraction to avoid corrupting or losing the data.

Retrieval often requires proprietary hardware and software tools specific to the truck’s make and model.

Data types, retention times, and extraction methods vary by manufacturer and device.

This leads to a critical sequence in which minor errors can result in the loss of crucial evidence.

Make and Model Specific Access

Different truck manufacturers (e.g., Freightliner, Volvo, Peterbilt) use proprietary ECM/EDR systems, each with unique data formats, storage capacities, and access protocols.

The type and detail of data recorded and the tools required for extraction can vary widely by brand and model.

Some manufacturers provide more comprehensive data (such as GPS, hours of service, and mechanical diagnostics), while others may record only basic crash or engine parameters.

This lack of standardization means that the process and ease of data retrieval can differ significantly depending on the truck’s make and year.

Many fleets use aftermarket ELDs or telematics devices, which may have their own access procedures and data retention policies, further complicating retrieval.

Information Captured

Insights into the driver’s behavior and the truck’s usage patterns, such as whether the driver adhered to mandatory rest breaks, highlight potential fatigue.

Records of when and how the brakes were applied or if the throttle was engaged provide insight into the driver’s perception and reaction time and whether evasive actions were taken to avoid the accident.

Monitoring steering inputs can also reveal whether evasive actions were made, reflecting attempts to maneuver the vehicle out of a dangerous situation or correct course.

Acceleration and Deceleration Patterns

Patterns show how the truck was being driven over time, which can indicate reckless or cautious driving behavior.=

Monitoring parameters such as engine revolutions per minute (RPM), load, horsepower, and operating temperatures can reveal potential violations of gross vehicle weight.

The same is true for records of fuel usage, total miles driven, idle time, and calculates overall fuel efficiency.

This data captures when and how brakes are applied, including anti-lock braking system (ABS) activity and hard braking events; how much the accelerator is being pressed; clutch engagement and gear selection, and when cruise control is activated or deactivated.

Mechanical and diagnostic data includes stored diagnostic trouble codes (DTCs), fault codes, and maintenance alerts for issues like engine problems, reduced tire pressure, or airbag malfunctions.

Operational history tracks engine usage history, maintenance intervals, service alerts, and audit trails.

Additional parameters may include seatbelt usage, tire pressure, yaw rate, roll angle, steering wheel angle, longitudinal and lateral acceleration, and GPS location (if integrated with telematics).

Summary: Common ECM Data Points

Data Type	Examples/Details
Vehicle speed	Current and historical speeds
Engine performance	RPM, load, horsepower, temperature
Fuel data	Consumption, efficiency, idle time
Braking	Brake application, ABS activity, hard stops
Throttle/clutch/gear	Throttle position, clutch use, gear selection
Cruise control	On/off status, usage history
Diagnostics	Fault codes, DTCs, maintenance alerts
Event data	Pre/post-crash details, sudden deceleration
Driver behavior	Acceleration, deceleration, idling
Other	Seatbelt use, tire pressure, GPS (if available)

Retention Period

The time an Engine Control Module (ECM) stores data before it is overwritten varies.

Much depends on the type of data, the make and model of the ECM, and the specific event recorded.

Most ECMs have limited storage capacity and use a rolling buffer.

This means the oldest data is overwritten as new data is recorded.

For example, speed, engine RPM, throttle position, and braking events may only be retained for a set period of engine cycles before being overwritten.

This period can range from a few minutes to several days or weeks, depending on the ECM’s memory size and how much the truck is used.

When a significant event (e.g. crash or sudden deceleration) occurs, such as a crash or hard braking, the ECM may record detailed data for a short window.

In some systems, the new data may overwrite the previous event data if another triggering event occurs.

Diagnostic trouble codes (DTCs) are typically stored until manually cleared with a diagnostic tool or automatically cleared if the fault condition no longer exists for a certain number of drive cycles.

Some DTCs may persist until the ECM is reset or the battery is disconnected.

In some cases, such as airbag deployment or certain critical system failures, the data may be locked and stored indefinitely, only removable with specialized procedures or equipment.

Litigation Hold and Spoliation

No universal federal legal requirements mandate preserving Engine Control Module (ECM) data in commercial trucks after an accident, simply because an accident occurred.

As such, it is imperative for crash victims (typically through their lawyers) to take action that imposes a duty on the motor carrier to preserve ECM data.

Typically, this will come from a litigation hold letter, followed by a protective order or injunction.

Once a litigation hold/preservation demand letter is sent, the receiving party is typically obligated to preserve the items for civil litigation.

If a company intentionally destroys ECM data after receiving a preservation request or when litigation is reasonably anticipated, courts may impose sanctions for spoliation of evidence.

This can include adverse inferences against the party that destroyed the data.

Regardless, attorneys or parties seeking to preserve ECM data after a truck accident should act quickly to request preservation or seek a court order, as ECM data is often overwritten during continued vehicle operation.

Summary Table: ECM Data Required?

Scenario	Duty to Preserve?
Accident occurs, no litigation or request	No general duty
Litigation is anticipated or initiated	Duty may arise
Plaintiff or party issues preservation request	Duty may arise
Court/protective order issued	Duty to preserve
Company policy requires preservation	Duty to follow one’s own policy

Working With Sam Aguiar Injury Lawyers

Due to the complexity of these cases, it is essential to work with a trucking attorney after a truck accident.

These lawyers understand the regulations that govern trucking and the need to respond before evidence gets lost or destroyed rapidly.

Additionally, a truck accident lawyer can ensure critical evidence, such as black box data, is promptly acquired and preserved, giving you the best chance at receiving the compensation you deserve.

If you’ve been injured in an accident caused by a truck driver, let us get to work for you.