Digital evidence is often the silent witness to an accident. Captured and stored via an Event Data Recorder (EDR), collision investigators can retrieve data from a vehicle with details of the events which occurred in the seconds before and after an incident.
Nature of the Incident
Our Insurer client’s policyholder was driving when he said that he suffered some sort of medical episode, blacked out and came round to find that he had been involved in a collision with two vehicles, resulting in injury to several of their occupants. In order to ascertain whether their policyholder was negligent, proof was required as to whether the driver had been able to exercise any control over the vehicle.
TRL was instructed to inspect the policyholder’s vehicle and to download the EDR to consider:
- Had any braking been applied
- What were the vehicle speeds prior to and at the point of collision
TRL Expert Witness View
The policyholder’s vehicle EDR was interrogated using our Bosch CDR (Collision Data Retrieval) equipment. This established that there was no brake application recorded and there was no significant change in engine speed or steering angle. Whilst at face value this may corroborate the policyholder’s account, we needed to establish whether the vehicle systems and sensors that populate these data fields were functioning correctly.
To complete this, the vehicle was subjected to an interrogation of the Electronic Control Units (ECUs) that form the electronic architecture of the vehicle, using Bosch KTS diagnostic equipment. Modern vehicles have multiple vehicle networks that allow the individual ECUs to receive and transmit data. Using electronic hardware and software it is possible to access the networks and ECUs to retrieve data that could be associated with an “event” or failure/damage to a vehicle component or system.
Should a monitored electronic component become defective, or the parent ECU identify an out of parameter signal, an ECU will record the fault by way of a Diagnostic Trouble Code (DTC). Typically, and depending on the initial programming of the ECU for the specific DTC, the DTC will contain what is known as freeze-frame data. Freeze-frame data is a snapshot of the vehicle’s pre-specified operating condition when the error message (DTC) first occurred. This data can include engine speed of the vehicle as well as, for instance, odometer and vehicle time recordings, to identify when the DTC occurred.
Within the DTC record, there could be frequency counters to identify how many times the defect has been identified as present, something that is of relevance to the investigation of collisions and in determining the drivers’ awareness of a vehicle related defect.
During our inspection the equipment enabled us to view and record sensor operation, confirming that key systems, linked to the EDR report, were functional. This is represented in the chart below.
The data was analysed and the following conclusions drawn:
- it suggested that no braking was undertaken by the driver, and that there were no aggressive steering inputs made
- the engine RPM (Revs Per Minute) remained reasonably static throughout all the recorded events, suggesting that there was no harsh application of the accelerator pedal by the driver
Successful data download and rapid response to the client, outlining evidence found in the form of a Letter Of Advice (LOA).