Black Boxes: Semi-Trucks (Usually) Have Them Too

If you pick a semi-truck at random on the highway, odds are good that the vehicle will have at least one piece of equipment that is popularly referred to as a black box. Does this mean that if the truck got into an accident, a firefighter could extract a virtually indestructible black cube from the wreckage? From that box, would they gain access to voice recordings and vehicle data to reconstruct how the crash happened? No, and not really.

First of all, airplane black boxes have flight data recorders that can survive fiery collisions or plunges into the ocean. None of a semi-truck's black boxes are built to survive a fire or serious water damage. Secondly, the event data recorders on a semi are just not as sophisticated as an airplane's. That said, if a semi-truck's black box survives an accident, it could contain data that's helpful for piecing together pre-crash information. This could include data that indicates whether the truck was overdue for repairs, if the vehicle was exceeding the speed limit, if the trucker had been driving for too many hours in one stretch, and so forth.

The reason why there isn't a 1-to-1 correlation between a plane's black box and that of a truck is that, strictly speaking, a black box is a flight data recorder. However, in everyday use, "black box" has been used to describe various data recorders for all kinds of vehicles, not just aircraft. Since this wider meaning is used colloquially by even legal professionals and accident reconstruction experts, from here on out, we'll stick to the informal, more inclusive usage of the term black box.

Where Did Black Boxes Come From?

The first device that we would consider a black box was used on trains. The original on-train monitoring recorder was used as early as the 1890s to record the path a train took, along with time stamps and speed data. The term "black box" itself is said to have been coined around 1939 when French inventors mounted a device onto airplanes that could automatically record speed and altitude on film. This incipient technology was encased in non-reflective black metal.

Over the years and around the world, engineers would develop this technology further for military aircraft, working to find a way to ensure that these black boxes could survive the impact of a crash. In the 1950s, an Australian scientist created the cockpit voice recorder with civilian planes in mind. In the decade to follow, many countries would mandate that this automatic voice recorder be included in airplane black boxes. It was around this time, the 1960s, that black boxes began to take on their modern orange color and irregular shape, not a box anymore, but something like a boxy-L-with-a-cylinder combo.

By the 1970s, event data recorders (EDRs) made the leap to passenger cars. This iteration of black boxes was first installed by manufacturers to monitor when airbags deployed. This was to ensure that the vehicle's safety system worked and to find ways to improve the technology. Decades later, just before the turn of the millennium, the National Transportation Safety Board (NTSB) started to recognize how useful this EDR could be for some post-crash analysis.

Black Boxes in Semi-Trucks

Back to the semi-truck we picked out on the highway earlier. What kind of black box would it have? While there are commercial motor vehicles on the road with none of the following, especially vehicles of an older build, our hypothetical truck would probably have one or all three of the following types of black boxes, especially if it was built in the 1990s or later.

1) Event Data Recorder (EDR)

If our truck had an airbag, chances are that if we looked into where the airbag was mounted, nearby there would be a compact gray box of metal, covered in yellow and white stickers. One of those stickers would read "Air Bag Sensors", and this would be the EDR. Just as it was for cars, the EDR for heavy trucks was built to monitor airbag deployment in the event of a crash. Over the years, the EDR was developed to automatically record more and more information in the seconds before, during, and after a trucking accident. If there is no crash, then no data is stored. The EDR only springs into action when the airbags are set off.

Most EDRs today can capture information such as whether:

  • The trucker was braking or accelerating
  • The driver was wearing a seatbelt one second before the event
  • The airbags worked, and if so, how long they took to deploy
  • There were multiple impacts during the crash

In some cases, EDRs can also record lateral and forward movement during an accident, data on the electronic stability control and steering capabilities, and more.

These heavy truck EDRs are not required by law (not even airbags are required in some semi-trucks!). However, if an EDR is present in a commercial motor vehicle that was made in September 2010 or later, they have to meet certain NHTSA regulations, such as supporting certain data-recording capabilities.

EDRs & Semi-Truck Accidents

If you get into an accident with a semi-truck, then the EDR would automatically record a seconds-long snapshot of that crash. It's possible for specialists with the right equipment to access the EDR for information on some driving behaviors (e.g. not applying the brake) and vehicle malfunctions (e.g. loss of steering) that might have contributed to the accident. However, if the trucker kept driving and experienced another event, such as hitting a massive pothole or getting into another collision, then that new event snapshot would overwrite the snapshot recorded of your accident. If a semi-truck has an EDR, it's vital to access data as soon as possible after the accident so the crash data doesn't get replaced with another event's information.

2) Electronic Logging Device (ELD)

If you were looking for an ELD in the wreckage of a truck accident, you might be looking for a small black or gray box, maybe something that looks like a mini game console. It might also be connected to a display on the dashboard. It could also not be truck hardware at all but be entirely contained in the software of the truck driver's smartphone (or another mobile device). That's because an ELD was also not built to record accident data. Still referred to as a black box anyway, the ELD was first made for Hours of Service (HOS) compliance. The ELD creates a paper-free way for truckers to log their on-duty hours and provides a built-in system to warn drivers when they're close to exceeding the legal limit for hours on the road.

Depending on how new the ELD is and who made it, an ELD can automatically record data such as:

  • Driver ID info
  • Motor carrier
  • Engine hours
  • Miles traveled
  • Location (within a 10-mile radius when the driver is off duty, otherwise it's down to a 1-mile radius)

Whatever type of ELD you find on a semi-truck, this stored data can typically be accessed by USB, email, or Bluetooth. It would also have sent this information to the carrier. By law, carriers and truckers need to hold onto their ELD data for six months.

ELDs & Semi-Truck Accidents

If an accident involved a commercial motor vehicle, there will often be an ELD in the picture. The Federal Motor Carrier Safety Administration, or FMCSA, mandated ELD black boxes in commercial trucks in December 2015, giving the trucking industry until December 2017 to comply. Exceptions to this mandate include certain short-haul drivers and tow truck drivers. If a driver is operating a truck that was built before 2000, they can be excluded from using an ELD as well.

What could the ELD tell us about an accident? If, for example, the trucker was driving past HOS limits, or the trucking company was using the ELD to harass the driver by cutting their rest times short or forcing them to drive in dangerous conditions, then the ELD could provide a crucial record of this negligent, illegal behavior. This type of black box then is particularly handy for reconstructing accidents where truckers or carriers violated regulations.

Can any of this data be overwritten or manipulated? No. While a trucker can make edits, such as noting that they had mistakenly changed their status to off-duty instead of "on-duty not driving", this edit would be added alongside the original record, but the original record would stay the same. By design, the ELD's original record cannot be changed, as the goal was to prevent a carrier from dishonestly reducing a driver's hours and cheating them out of pay.

3) Electronic Control Module (ECM)

As far as semi-truck equipment is concerned, the ECM can typically offer the most comprehensive record of accident-related information. You would look for the ECM near the engine, as this box-like, metal component is often described as the engine's brain or computer. Sometimes black, sometimes gray, this box can track everything from battery voltage and coolant temperature to vehicle location, speeds, and more. It can also regulate aspects of a vehicle's performance.

ECMs vary in sophistication, but many semi-truck ECMs can capture data such as:

  • Accelerations and decelerations with time stamps
  • How harshly brakes were applied
  • Cruise control usage
  • Fuel usage
  • Distance traveled
  • Average MPH
  • How long the vehicle went 65 MPH or faster
  • The highest MPH and RPM of a trip
  • Vehicle diagnostics

ECMs & Semi-Truck Accidents

This may be no surprise at this point, but like the other black boxes, ECMs were not originally built to capture accident data either. It was meant to help fleet management stay on top of vehicle maintenance and repairs, helping carriers to prevent crashes. Even though its use for determining the cause of a truck accident is incidental, it can be a rich mine of key data that can corroborate witness testimony or else call it into question.

However, the sophistication of an ECM does not translate to any more durability than the other semi-truck black boxes. The longest an ECM can hold onto data is usually 30 days. Past that point, as long as the vehicle keeps driving, the new information will keep overwriting historical data. The ECM can deteriorate over time, and it probably won't survive a vehicle fire either. That is why it's crucial to retrieve ECM data as soon as possible after an accident, which would require getting an expert with specialized equipment on the scene to download and interpret the data.

How Reliable Is a Semi-Truck's Black Box Data?

It depends. As far as accident survival odds, a black box isn't really any sturdier than other parts of a semi-truck's engine or dashboard. The amount of time that data can last is limited before it expires or is overwritten by new information. As there are electrical aspects to each type of black box, each system can also experience glitches. It is possible for some data to simply be lost. The specific data any black box can automatically capture will also vary a great deal based on the engine maker, vehicle manufacturer, and the year everything was made.

However, this vulnerability and variability do not invalidate the information these black boxes can provide. If the data can still be accessed and isn't damaged, then it's deemed useful—and even admissible in a court of law. In fact, these black boxes have been used not just in civil accident cases, but in criminal investigations and cases as well.

Compared to impressionable human memories and the effects that trauma and shock have on a person's perception, a semi-truck's black box(es) can provide invaluable hard data to work with. These semi-truck black boxes can cover everything from how fast a truck was going to how fatigued a driver was and how irresponsible a trucking company may have been in the upkeep of their vehicles. As black box technology continues to develop, personal injury lawyers and courtrooms are only more likely to continue to rely on these devices as sources of crucial accident information.

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