Tell you the truth of crash accident-------HEDR Vehicle Event Data Retrieval System

Traditional investigation methods rely on limited information such as road and vehicle marks, surveillance videos, and eyewitness accounts. These methods are labor-intensive, prone to inaccurate conclusions, and lack objectivity, especially in the absence of witnesses, videos, or in bad weather conditions. Moreover, traditional methods struggle to determine drivers' pre-crash emergency actions, hindering fair and just accident handling and impeding accident prevention efforts.

The advent of the Automotive Event Data Recorder (EDR) has revolutionized traffic accident investigation. Similar to an airplane's black box, EDR records collision-related data of vehicles and occupant protection systems before, during, and after the event, providing objective, complete, and accurate accident information.

EDR typically records vehicle data for a period of time prior to a collision. This includes,

By analyzing EDR data, we can accurately obtain the following information: the vehicle's condition before the accident and the driver's actions before the accident.

Research has shown that EDR data can corroborate traditional identification results, providing data support for the accuracy of the results, while reducing the workload and difficulty of accident identification. It plays an important role in accident identification.

Specifically, the benefits of EDR data in accident identification are reflected in the following aspects:

-Improved accuracy:   EDR data objectively records key information such as vehicle status and driver behavior before, during, and after the accident, providing reliable evidence for accident identification and improving the accuracy of the results.

-Reduced workload:   EDR data can directly reflect the accident process, reducing the workload of accident investigators in scene investigation and data analysis, and improving work efficiency.

-Auxiliary analysis:   EDR data can provide a new perspective for accident cause analysis, helping investigators to understand the causes of accidents more deeply and thus formulate more effective preventive measures.

 

Application of the EDR data:

After statistical analysis of the EDR data of 114 cars involved in accidents, mainly data reflecting the driver's emergency response behaviour before the collision, such as brake pedal position, time of brake application, vehicle speed during braking and the amount of speed change in the braking phase (the difference in speed from the start of braking to the end of braking or at the time of the collision). Of the 114 passenger cars, 62 had the brake pedal depressed prior to the collision, 25 did not have the brake pedal depressed, and 27 did not have the brake pedal use status field recorded, as shown in Figure 1.

Figure 1 Braking Status Pre-collision

Of the 62 vehicles that applied braking before the collision, the most vehicles applied braking within 1 second before the collision (17 vehicles, or 27.4%), the second most vehicles applied braking within 2-3 seconds before the collision (15 vehicles, or 24.2%), and the fewest vehicles applied braking within 4-5 seconds before the collision (7 vehicles, or 11.3%). The percentage of vehicles that started braking within 3 seconds before the collision was 71.0%, indicating that the vast majority of drivers were able to take emergency action within 3 seconds before the collision, as shown in Figure 2.

Figure 2 Distribution of the start of braking time

Among the 62 vehicles that applied braking before the collision, the distribution of vehicle speeds during braking is shown in Figure 3, the number of vehicles with initial speeds below 30 km/h during braking is closer to the number of vehicles with initial speeds between 30 km/h and 60 km/h and above 90 km/h, and the percentage of vehicles with initial speeds between 60 km/h and 90 km/h during braking is 40.3%. Overall, more than half of the cases, 58.1%, involved vehicles with initial braking speeds above 60 km/h.

Figure 3 Braking initial speed

Among the 62 vehicles that applied braking before the collision, the distribution of the average initial braking speed and the amount of change in the average braking speed with the time of the start of braking are shown in Figure 4. From the figure, it can be seen that the earlier the start of braking time, the more the amount of change in the average braking speed tends to increase; the indicating that the 11 vehicles in this range have relatively high running speeds.

Figure 4 Braking speed distribution with time