9/17/2013Dr. Khalil

ME 8020 – Crashworthiness and Occupant

Protection in Transportation Systems -I

Week 3 – Lecture 5

Crash Data

(NASS, GES, CDS, SCI, FARS)September 12, 2013

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History of Crash Investigations

9/17/2013Dr. Khalil

NHTSA was created in 1970 following the Highway Safety and Motor Vehicle safety acts of 1966 (www.nhtsa.dot.gov)

It deals with traffic safety issues: Safety standards Research on biomechanics of injury Research on vehicle crashworthiness Vehicle safety ratings Consumers complaints Crash investigations Statistics (NCSA) Etc.

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History of Crash Investigations

9/17/2013Dr. Khalil

Cornell University - Crash Injury Research (CIR) Project

Hugh DeHaven - pioneered aircraft crash investigation -1940’s

Automobile CIR began in 1953 at Cornell Aeronautical Labs

(now Cal span?)

U of M - Huelke/Gikas began investigating fatal crashes – 1960’s

Identified design features contributing to injuries

Evolved over time to in-depth studies

Multidisciplinary accident investigation teams

Approach based on Haddon Matrix

Investigators from many disciplines

Formalized in-depth investigations

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History of Crash Investigations (NCSS)

9/17/2013Dr. Khalil

NCSS - National Crash Severity Study

Pilot program 1977 - 1979

Designed by UMTRI

Statistically representative crash investigation data base

Detailed info on cars & occupants

Towed away vehicles

7 geographical areas

Stratified sampling plan

Statistical weighting

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Crash Investigation Databases

• NHTSA designed & developed the following data

systems to provide overall measure of highway

safety:– FARS

– NASS/GES

– NASS/CDS

– NASS/SCI

– CIREN

• NHTSA’s Website - publicly available data files

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NASS - National Automotive Sampling System

Based on NCSS Operating since 1979 Randomly select representative cases from hundreds of

thousands of Police Accident Reports (PARS) Randomly select areas of U.S. counties and cities www.nhtsa.dot.gov/departments/nrd30/ncsa/NASS.html

Crash Investigation Databases (NASS)

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Crash Investigation Databases (NASS)

9/17/2013Dr. Khalil

NASS: two major data bases

- General Estimate System (GES)

Focus on overall cash trends, big picture- Crashworthiness Data System (CDS)

Focus on injuries in passenger vehicles to propose improvements

&

- Specific Crash Investigations system (SCI) Focus on specific highway safety issues, as may be mandated by congress or some research issue concerning new technology

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Crash Investigation Databases (NASS)

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General Estimate System (NASS/GES)

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Started in 1988

Collects data from large sample of police reported crashes annually

Crashes of all severities

Nationally representative sample

Doesn’t investigate crashes

Only basic PARS data entered

Annual report (NASS/GES) published

Tracks trends and overall crash picture

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Crashworthiness Data System (NASS/CDS)

9/17/2013Dr. Khalil

Collects detailed data from thousands of police reported towed, passenger vehicle crashes per year

Focus on injuries to recommend design improvements Uses trained, professional investigation teams Information collected include: exterior damage,

interior damage, injuries, scene investigation, environmental conditions, etc.

Detailed, in-depth information Vehicle damage VIN Crash delta V from CRASH 3 Injuries and occupant details

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Specific Crash Investigations (SCI)

9/17/2013Dr. Khalil

Conducts investigations to acquire detailed information on highly visible traffic crashes

Examine the impact of new safety technology such as air bags, alternate fuel systems

Investigate airbag inflation-related deaths and serious injuries

Investigate alleged defects

Helps the agency in formulating response to its internal customers (safety standards, R&D)

Develops new technology to improve traffic safety

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9/17/2013Dr. Khalil

CIREN –

Created in 1996 by NHTSA ER-based investigations of crash injuries at 8 level 1 trauma

centers Multi-disciplinary teams of clinicians and engineers from

industry, government, and academia The file includes data from severe motor vehicle crashes,

including crash reconstruction and injury description

Crash Investigation Databases: CIREN(Crash Injury Research & Engineering Network)

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CIREN Centers Locations

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Fatality Analysis Reporting System FARS

9/17/2013Dr. Khalil

It monitors all fatal crashes on public roads in the U.S. and Puerto Rico

STARTED IN 1975

FARS data files on NHTSA website since 1996 (www.fars.nhtsa.dot.gov/)

It must involve a death of occupant and/or pedestrian

Based on police collected data

Each case file contains >100 entries, characterizing the vehicle, the occupants, etc.

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Fatality Analysis Reporting System FARS

9/17/2013Dr. Khalil

Four forms:

Accident form: information on date, time, location, number of vehicles involved, number of people involved, other information, …

Vehicle form: type, impact point, ….

Driver form: license, alcohol, ….

Occupants form: age, gender, injuries, ….

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Police-Collected Data

9/17/2013Dr. Khalil

All Injury-producing collisions (passenger cars, trucks, motorcycles, pedestrians) on public roads in a given state

May not report off-road or private-property damage

Fatal crashes investigated most thoroughly Location Environment Vehicles Injured occupants Circumstances Narrative & diagram of accident

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Police-Collected Data

9/17/2013Dr. Khalil

States collect & computerize some records:

Driver

Traffic engineering

Selective enforcement

Problem identification

Narrative & diagrams not stored

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Police-Collected Data

9/17/2013Dr. Khalil

Injury Coding:

K - Fatal

A - Incapacitating injury

B – Non incapacitating injury

C - Minor injury

O - Not injured

Vehicle Damage:

Area of damage indicated on chart

Damage coding (some states) 0 -7 Scale Officer compares to pictures

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Police-Collected Data

9/17/2013Dr. Khalil

Problems:

Vehicle identification may be difficult Level of detail poor Lack of specific injury identification Crude estimate of crash severity Some data can be suspect No standard format

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In-Depth Investigations

9/17/2013Dr. Khalil

Trained investigatorsSponsors include: Insurance companiesAuto manufacturersGovernment agencies

On-scene investigation (sometimes)

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In-Depth Investigations

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Detailed description of vehicle damage Hospital & autopsy reports Specific injuries (AIS) and contacts coded Expensive, thus small sample

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Abbreviated Injury Scale (AIS)

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0 no injury

1 minor

2 moderate

3 serious

4 severe

5 critical

6 fatal

7 (or 9) injured, severity unknown

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Methods of Analysis

Estimating Crash Severity: V

9/17/2013Dr. Khalil

Velocity change (V) based on: Pre-crash speeds Skid marks Vehicle trajectories from point of impact to final

position Crash damage measurement

Computer programs - CRASH & SMAC

Conservation of momentum & energy

Requires representative vehicle stiffness

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Methods of Analysis

HARM

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(Mallieris, 1980s)

Measure of cost to society

Allows analysis of major and minor Injuries

Used for cost/effectiveness studies

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Overview of Statistical Studies

9/17/2013Dr. Khalil

NHTSA’s National Center for Statistics and Analysis (NCSA) provides:

From FARS & GES - General Trends: Fatality and injury rates Age and gender Alcohol Vehicle Type (passenger, truck, motorcycle) Speed limit - rural v urban roads Time of day - weekday vs. weekend

From NASS/CDS Vehicle crash data Occupant injury data

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