What’s a black field – and what’s not

The list of car safety regulations set by the European Union is long. And soon it will be a noteworthy entry for even longer: In July, a black box will be mandatory in newly approved passenger cars. As usual with these approval regulations, Switzerland will also adopt a black box rule from the European Union. But what is the technical reason for storing the data of this event that the European Union is now describing? What to record and how to read – and is it really new?

The fact that Big Brother will always be in the passenger seat from July is causing an uproar. Excitement that experts share only to a limited extent. As André Blanc, Deputy Director of the Dynamic Test Center (DTC) at Vauffelin BE explains, this technology is not entirely new: “In the 1990s, General Motors installed a system that was able to log accident data. They wanted to protect themselves from lawsuits being committed by Customers, for example after an accident in which they are at fault.” Over the years, the system has become so popular with auto manufacturers that the Insurance Institute for Highway Safety (IIHS), the American Institute for Traffic Safety, has called for a uniformly standardized registration at the end of the decade The first of the 21st century. In 2012, the US government approved a legal framework for record-keeping procedures. But: US law does not force manufacturers to record data in their cars. The only requirement is to comply with certain standards if the data is recorded,” Andre Blanc explains.

Black box will not be mandatory

Based on US law and against the background of the stated goal of zero road traffic deaths by 2050, the European authorities have also created a legal framework for the black box. The event data storage regulations are part of a whole series of new requirements for standardization of new vehicles within the European Union. Switzerland adopts these regulations on the basis of bilateral agreements”, explains Marina Kampf, press officer at the Federal Roads Office (ASTRA). From this summer, the regulation applies to all new approvals. From 2024, all new certifications will be affected.

Andre Blanc knows exactly what is regulated in the regulation: “European requirements are basically the same as American ones. This does not mean that new vehicles must necessarily have an event data recorder. But if you have one, you should be able to communicate the relevant data to an external user in a unified manner”. Or in other words: Contrary to many claims to the contrary, the auto industry will still be able to register and sell vehicles without a black box in the future. Or: can. Because almost all new vehicles already have driving and accident data loggers. Andre Blanc recalls: “In 2006, I read a report that said that 95 percent of the cars that were put on the market at that time had accident data.”

Not really a black box

So what exactly was recorded in this black box? Andre Blanc insists that the event data store should not be called a black box: “Car registration systems have nothing to do with the black box in aircraft, which is where the term comes from. In aviation, these devices are constantly working and recording everything that happens. It doesn’t matter if an accident occurs or not. …In contrast, the event data memory in the vehicle only saves something when the event occurred—that is, an accident.” Although the data is permanently recorded in the event data logger, as it is known in English, it is constantly deleted as long as nothing happens.

This makes sense, after all, in the event of an accident, it is more interesting to know what happened immediately before than what happens next. So the event data logger records what happened within 250 milliseconds after the accident as well as in the previous five seconds. For accident experts, the previous five seconds are the most important. With it, you can read the incident, understand the process and keep track of exactly what happened. The event triggering the storage could be an inflated airbag, belt tensioner activation, or a significant deceleration of the vehicle’s speed: “Event data storage is also triggered if the speed drops by more than 8 km/h in a period of less than 150 milliseconds.” Blanc explains. This roughly corresponds to a deceleration of 14.8 m/s2That is about 1.5 grams. An accident involving a pedestrian is not necessarily enough to start recording.

In technical terms, the data stored by the event data logger is referred to as digital traces, a reference to slip markers, which have been an important tool for accident researchers for decades in reconstructing accidents. Of course, the event data recorder records more data than just the vehicle’s speed. “The event data recorder records many data such as the position of the accelerator and brake pedal, the steering angle of the wheels and the speed of the vehicle. But it also recognizes, for example, whether the occupants are stuck or not,” says André Blanc.

There is no separate component

Even if the recorded data is standardized according to the new regulation, memory itself is not a standard commodity. Each manufacturer or subcontractor authorized by them has its own event data logger. Unlike an accident data logger, such as that used by insurance companies, an event data logger is not even a separate component. Because the accident data recorder is a fairly independent device from the vehicle and can be installed and removed independently, the event data recorder is often integrated directly into the vehicle’s control units and obtains data from the vehicle’s CAN bus. Since all the safety-related data is located in the airbag control module, the event data memory is usually located there as well. There are technical requirements for analyzing the event data logger, because reading the data requires an appropriate interface. With the exception of Kia and Hyundai, all manufacturers operate with a system from Bosch. The event data logger can be accessed via the OBD interface at the bottom of the dashboard. If the EOBD is severely damaged – eg after a vehicle fire – the event data recorder can also be accessed directly with an appropriate diagnostic device.

There is no public access

In addition to the technical aspect, there is also the legal aspect of reading the data: “Except for the prosecutor’s request, no person may access the data without the vehicle owner’s permission. Not even insurance,” Blanc notes. Until a few years ago, records were only available to manufacturers, and they could not be read by third parties. However, the situation has changed in recent years, as manufacturers prepare to adopt the new regulations: “Volkswagen Group opened access to data as early as 2018, BMW in 2020. Now Mercedes is the last German manufacturer to deny access to the event data recorder” Blanc explains. Of course, Stuttgart will have to change its stance by summer.

What does the black box record?

The following data can be recorded by the event data recorder (black box) in the vehicle (the list is not exhaustive):

Vehicle speed Vehicle speed is often determined via wheel speed sensors (ABS sensors). Problems can arise when interpreting the data, for example if the wheels accelerate in the event of a rollover, which can be misinterpreted as excessive speed in the event of an accident. This underlines the importance of using experts to analyze accident data.

Throttle and throttle position The driver’s load requirements are recorded here before and immediately after an accident. Throttle and/or throttle position is measured as a percentage of the entire throttle. The event data logger receives this information over the CAN bus.

brake pedal The event data recorder receives information via the vehicle’s CAN bus whether or not the brake pedal is depressed.

Multiple Collision Detection An accident can consist of several single collisions, which the event data recorder must recognize. However, if the first effect occurred more than five seconds before the last, it could no longer be tracked, since the logging time window is in no way greater than five seconds before the last event.

airbag deployment Event data memory is often integrated directly into the airbag control unit. For accident analysis, it can be important to know exactly when the airbags are deployed.

The change in longitudinal velocity Delta v, that is, the change in the longitudinal velocity of the vehicles involved in an accident, is one of the most important variables in accident analysis, as the impact forces can be derived from it. It is recorded every 10 milliseconds before the 300 milliseconds and 250 milliseconds after the accident.

seat belt A sensor in the buckle can be used to record passengers who were wearing a seat belt during an accident.

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