I am trying to gather information on the reliability of the edr under conditions that are not optimum. Most specifically, when it is 14 degrees Fahrenheit, new precipitation, all weather tires, and a short stretch of road (1/2 mile) in a wooded area specifically an area going over a small stone bridge. Car is an Audi Q5.
My main question is- the speed recoded was very high- much higher than you’d ever imagine- and the driver reported he had no steering because he was sliding or had lost tire contact with the road?
Have you run any tests or evaluated any situations where there were these conditions? I think what I’m wondering is if there are situations when the edr would be picking up a higher tire rotation than was actually happening?
Thank you for any insight you can give.
edr readings on ice
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Bob Anderson
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Re: edr readings on ice
Good Morning,
The reliability of EDR data is well established and admissible in criminal litigation where the standard is beyond a reasonable doubt. This reliability has been established by comparing known crash and pre-crash conditions to that recorded by the EDR, including "suboptimal" roadway conditions. This is important as it is critical to understand when use of the EDR tool is appropriate and when it is not, as well as to understand what the EDR data looks like when the vehicle is hydroplanning for example.
The EDR function is simply a recording of the data available to the airbag control module over the vehicle's computer network. The EDR and the speedometer are getting speed data from the same source, typically the wheel speed sensors. So, if the speedometer can over-report the over-the-ground speed, then the EDR will too.
Most of the time, vehicle's tires are in contact with the roadway and rolling (not sliding) in the direction of the vehicle's travel, which is why the speedometer is able to indicate the speed. When vehicles are skidding, peeling out, spinning out, airborne, rolling over, etc. the speedometer reading and therefore the EDR speeds, do not represent the vehicle speed.
In your example, if the driver is applying sufficient accelerator pedal to overcome the friction with the roadway, so that the tires are spinning fast than the car is going, or peeling out, then in the same way the speedometer would over-report the vehicle's over-the-ground speed, so would the EDR.
The reliability of EDR data is well established and admissible in criminal litigation where the standard is beyond a reasonable doubt. This reliability has been established by comparing known crash and pre-crash conditions to that recorded by the EDR, including "suboptimal" roadway conditions. This is important as it is critical to understand when use of the EDR tool is appropriate and when it is not, as well as to understand what the EDR data looks like when the vehicle is hydroplanning for example.
The EDR function is simply a recording of the data available to the airbag control module over the vehicle's computer network. The EDR and the speedometer are getting speed data from the same source, typically the wheel speed sensors. So, if the speedometer can over-report the over-the-ground speed, then the EDR will too.
Most of the time, vehicle's tires are in contact with the roadway and rolling (not sliding) in the direction of the vehicle's travel, which is why the speedometer is able to indicate the speed. When vehicles are skidding, peeling out, spinning out, airborne, rolling over, etc. the speedometer reading and therefore the EDR speeds, do not represent the vehicle speed.
In your example, if the driver is applying sufficient accelerator pedal to overcome the friction with the roadway, so that the tires are spinning fast than the car is going, or peeling out, then in the same way the speedometer would over-report the vehicle's over-the-ground speed, so would the EDR.
Bob Anderson
Tempe, Arizona
Tempe, Arizona
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uwef_de
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Re: edr readings on ice
Spinning on a snowy surface may look like this (see attachment, own measurement data, engine rpm are just before the red zone). For clarification: the data are not EDR data (but ADR data). But they are comparable, because the source for "v-tacho" (speedometer) is also wheel speed.
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