# Presentation: 232693

## Motor Vehicle EDRs and Crash Data 

**Event Data Recorder Toptec **

**Susan A. Ferguson**

**Alexandria, VA ******** June 5, 2003**

**Motor Vehicle EDRs and Crash Data **

## Recommended EDR data elements

- 5 seconds prior to crash
- Belt use
- Throttle position
- Whether driver was braking, and whether antilock or electronic stability control features were activated
- Vehicle speed

## Recommended EDR data elements

- During the crash
- Longitudinal and lateral vehicle acceleration (1,000 data points/second)
- Delta V by time (100 data points/second)
- Delta V and delta T for the crash event, if delta V by time is not feasible
- Time of airbag deployment (including time of different stages of deployment)

## EDRs can provide useful information to understand vehicle performance and injury mechanisms in crashes

- Crash severity
- Airbag performance
- Seat belt use
- Injury mechanisms

## EDR usefulness in crash investigationsCrash severity

- Estimated delta V currently is only a partial measure of crash severity
- No information is available on delta T
- Two crashes with the same delta V can differ quite a lot in terms of severity if delta T differs
- A crash into the soft rear end of a vehicle will be much less severe than into a rigid barrier
- It’s not possible to estimate delta V in certain crashes, e.g. underride, override

**Notes:**
Estimation programs use information about vehicle damage, mass, stiffness, and principal direction of force
Relies on physical models that are very simplified representations of crashes

## Estimated delta V is only a partial measure of crash severity

**1991 Dodge Caravan struck rear of 1958 Chevrolet Bel Air**
**Estimated delta V 45 mph**

## 1958 Chevrolet Bel Air

**50 inches of crush**

**Notes:**
1991 Dodge Caravan struck rear of parked 1958 Chevrolet Bel Air
Delta V 45 MPH; front of Caravan crushed only 11 inches but rear of Bel Air crushed 50 inches
Driver: 35-year-old male, 66 inches, 160 pounds, unbelted, BAC 0.16; possible cardiac arrest before crash
Fatal injuries: full thickness laceration of right ventricle with hemopericardium (AIS 5) and interventricular septum  contusion (AIS 4)

**Estimated delta V 39 mph**

**Notes:**
34 year old male, unbelted
Died of chest and head injuries

## Front underride with initial engagement 

**2001 Honda Accord struck rear of Geo Storm**

**Notes:**
IIHS front-into-barrier: $163
Parts: bumpers only – bumper reinforcement bar and foam absorber
This case: replace bumper, hood, A/C compressor, radiator, and headlamps. Repair both fenders. 

## EDR usefulness in crash investigations Seat belt use

- Seat belt use can be difficult to assess in some crashes
- Based on investigators judgment or self-report
- Investigators can examine evidence e.g. D-ring scuffing or belt web striations, but such evidence not available in low speed crashes
- Because of reduced force on seat belts with airbags such evidence may not be as often available
- Belt use estimates in NASS/CDS are inflated

## EDR usefulness in crash investigations Airbag deployment data

- Airbag deployment data are critical in understanding airbag performance
- Timing of airbag deployment
- Airbags can deploy late in some crash circumstances, which will affect possible injury mechanisms
- Multi-stage inflators
- Investigators will need to know which stage/s deployed to judge whether airbag is doing its job

## EDR usefulness in crash investigationsUnderstanding injury

- Better correlation of crash severity with injury onset and injury severity
- For example at what delta V does whiplash occur for passenger vehicle occupants in rear impacts

## EDR limitations

- Information may be available only for frontal crashes
- Access to the EDR unit not always easy in crash investigations
- Need standard methods to download and interpret information
- EDR data not infallible
- Need to look at other available evidence from the investigation to be sure it makes sense

## Vehicle velocities over time before and after            a crash using crash test data

**Vehicle velocities over time before and after            a crash using crash test data**

**-0.05**

**0.05**

**0.15**

**0.25**

**0.35**

**Time (sec)**

**2002 Chevrolet TrailBlazer**

**-0.05**

**0.05**

**0.15**

**0.25**

**0.35**

**Time (sec)**

**2003 Cadillac CTS**

## Vehicle velocity over time before and after                a crash using crash test data

**Vehicle velocity over time before and after                a crash using crash test data**

**-0.05**

**0.05**

**0.15**

**0.25**

**Time (sec)**

**2003 Lincoln Town Car**

**0.35**

**-0.05**

**0.05**

**0.15**

**0.25**

**0.35**

**Time (sec)**

**2002 Chevrolet TrailBlazer**

## Summary

- EDRs can be very useful to crash investigators and researchers in understanding vehicle crashworthiness, and potential for crash avoidance
- Currently, limited EDR information available in most vehicles
- Ease of access and use will maximize usefulness to non-traditional users e.g. police departments
- EDR data elements and access should be standardized

## www.highwaysafety.org

**www.highwaysafety.org**

**For more information:**