Crash Data Sets and Analysis Overview Flashcards
What are three sources of traffic safety data?
- Police crash data
- Medical crash data
- Safety survey data
What are some sources of data that supplement traffic safety data?
- Roadway and traffic data
- Population
- Licence/registration data
- Travel survey data
- Sociodemographic/economic data
What is the typical property damage dollar-amount threshold that a crash must exceed before a police report is required?
$1k-$1.5k
What are two limitations of police crash data?
- Not all crashes are documented in police crash reports
- Police reports are only required for crashes with sufficient sustained damage.
- Every police jurisdiction reports differently.
What organization has attempted to standardize poice crash reporting?
the Model Minimum Uniform Crash Criteria (MMUCC) Committee
What are the five general types of information in police crash reports?
- Location information
- Environmental Information
- Vehicle Information
- Driver Information
- Injury Severity
What kind of location information is typically included in police accident reports?
- Street names
- Mile markers
- GPS
What kind of environmental information is typically included in police accident reports?
- Weather condition
- Lighting condition
- Surface condition
- Crash type
What kind of vehicle information is typically included in police accident reports?
- Assigned sequential unit number within the crash
- Unit type
- Vehicle type
- Make/Model/Year
- Vehicle Movement
- Maneuver prior to crash
What kind of driver information is typically included in police accident reports?
- Driver’s license information
- Alcohol or other drug involvement
What are three injury categorization schemes typically used in police accident reports?
- 2 categories: Fatal and non-fatal
- 5 categories: KABCO
- Abbreviated injury scale
Describe the KABCO injury classification scheme.
5 injury categories:
- K = Fatal
- A = Incapacitating injury
- B = Capacitating injury
- C = Possible, minory injury
- O = No injury
What is the benefit of using the Abbreviated Injury Scale in police accident reporting.
Matches medical systems data better.
What is the Fatality Accident Reporting System (FARS)?
A census of traffic crashes that have resulted in the death of a person involved in a crash within 30 days of the crash
What geographies does the Fatality Accident Reporting System (FARS) include?
- All 50 U.S. states
- Washington D.C.
- Puerto Rico
When did the Fatality Accident Reporting System (FARS) first become available?
1975
How many total data elements does the Fatality Accident Reporting System (FARS) include?
100 elements
What are the thee categories of data elements included in the Fatality Accident Reporting System (FARS)?
- Accident/Crash
- Vehicle
- Person
What are some examples of accident/crash data elements in the Fatality Accident Reporting System (FARS)?
- Environment
- Time/Date
- Collision Type
- Weather
- First Harmful Event
What are some examples of vehicle data elements in the Fatality Accident Reporting System (FARS)?
- Vehicle type
- Crash avoidance maneuver
- Principle impact points
What are some examples of person data elements in the Fatality Accident Reporting System (FARS)?
- Age
- Gender
- Person type (driver, occupant, pedestrian)
- Seating position
- Injury severity
- Restraint use
What is the Crash Reporting Sampling System (CRSS)?
A national sample of traffic crashes involving all levels of severity ranging from no injury to fatal injury
Crash data from how many police agencies are included in the Crash Reporting Sampling System (CRSS)?
400
Crash data from how many geographic sites in the U.S. are included in the Crash Reporting Sampling System (CRSS)?
60
Does the Crash Reporting Sampling System (CRSS) include the same data elements as FARS?
Yes
What is the Highway Safety Information System?
A multistate database merging crash, roadway, and traffic data only including states with high quality police crash report data (hsisinfo.org)
Which 9 states are included in the Highway Safety Information System?
- Washington State
- California
- Minnesota
- Illinois
- Ohio
- North Carolina
- Maine
- Michigan
- Utah
Does each state included in the Highway Safety Information System provide the same set of police crash report data?
No
What police crash report data elements does Illinois include?
- Accident
- Road log
- Bridge
- Railroad grade crossing
What police crash report data elements does Minnesota include?
- Accident
- Road log
- Reference post
- Traffic
- Intersection
- Bridge
- Railroad grade crossing
What is mecial crash data referred to as?
The Injury Surveillance System
What does medical crash injury data include?
Motor vehicle crash (MVC) data on:
- any person injured
- the subset of injuries
Who is Injury Surveillance System (ISS) data available to?
- Health-related agencies
- Some outside agencies
Which medical crash databases in the Injury Surveillance System (ISS) does NHTSA include?
- Emergency medical service run report database
- Trauma registry database
- Hospital discharge database
What does the EMS run report database include?
Injured persons who received care and transport from EMS providers
What is a limitation of the EMS Run Report Database?
EMS run reports are not standardized
What are the National Emergency Medical Systems Information System (NEMSIS) defined standard elements (nemsis.org)?
- Service information
- Treatments
- Charges
- Dispatch time
- Date
- Geographic Location
- Demographic information on EMS provide and personnel
- Equipment
What does the Trauma Registry Database include?
Records of trauma patients receiving treatment typically at designated trauma centers.
How is the American College of Surgeions involved in the Trauma Registry Database?
- certifies trauma centers
- sets data element collection guidelines for trauma cases
How is the Trauma Registry Databases complied?
States certifying trauma centers combine registry data on all trauma cases
What does the Hospital Discharge Database include?
Records of:
- inpatients and outpatients admitted to the hospital
- reason for visit
- treatment codes
- charges
- traffic crash codes
What is a major challege with medical crash data?
Due to privacy concerns, it is very difficult to obtain access to medical records even if all PII is removed.
What organization developed the Crash Outcomes Data Evaluation System (CODES) Database?
NHTSA
Why did NHTSA develop the Crash Outcomes Data Evaluation System (CODES) Database?
To link police crash reports and medical crash databases
What method does the Crash Outcomes Data Evaluation System (CODES) Database use for linking poolice crash reports and medical crash database records?
The probablistic matching method
What is the probablistic matching method used in Crash Outcomes Data Evaluation System (CODES) Database?
A measure of the statistical likelihood that two records pertain to the same incident/case.
How is the Crash Outcomes Data Evaluation System (CODES) Database useful?
- Produces aggregate statistics
- Analyzing the outcomes and costs of traffic crashes at state and national levels
How is Traffic Safety Survey Data collected?
Telephone surveys
Who collects Traffic Safety Survey Data?
NHTSA
What is the purpose of Traffic Safety Survey Data?
Understand:
- Attitudes
- Opinions
- Self-Report Behaviors
What is the MVOSS?
Motor Vehicle Occupant Safety Survey (6000 respondents)
What is the DDAB?
National Survey of Drinking and Driving Attitudes and Behavior (7000 respondents)
What kind of data is included in the National Occupant Protection Use Survey (NOPUS)?
Probability-based observation data on the use of restraints and electronic device use
When was the first National Occupant Protection Use Survey conducted (NOPUS)?
2000
How many sites are represented in the National Occupant Protection Use Survey (NOPUS)?
1800
Surveys of what are included in the National Occupant Protection Use Survey (NOPUS)?
- Moving traffic
- Controlled intersections
Which organization’s website houses the Web-based Injury Statistics Query and Reporting System?
the Center for Disease Control (CDC): cdc.gov/injury/wisqars/index.html
What is the Web-based Injury Statistics Query and Reporting System?
An online database with data on:
- fatal and nonfatal injury injury
- Violent death
- Cost of injury
Does the Web-based Injury Statistics Query and Reporting System inclue only MVC data?
No. It includes other elements such as suicide and homicide. But it is sortable by MVC.
How is the Web-based Injury Statistics Query and Reporting System organized?
By intentional vs unintentional injuries
What is the leading cause of unintentional injury in the Web-based Injury Statistics Query and Reporting System?
Motor vehicle crashes (MVC)
What age group is particularly affected by MVCs according to the Web-based Injury Statistics Query and Reporting System?
People < 24 yo
What does roadway data refer to?
Physical raod data such as:
- horizontal curve
- functional classification
What does traffic data refer to?
Traffic volume
What organizations maintain roadway and traffic data?
State Transportation Departments (DOTs)
What does the Roadway Inventory Database contain?
Physical and use characteristics of:
- roadway segments
- intersections
What do commercially available versions of HERE or other mapping software pertain to?
the Roadway Inventory Database
What are some examples of data elements that mapping softwares, such as HERE, get from the Roadway Inventory Database?
- Number of lanes
- Access control
- Functional class
- Speed limits
- Junction type
What does the Traffic Database contain?
Traffic volume characteristics such as annual average daily traffic (AADT)
Describe the Highway Performance Monitoring System.
National highway system database with peformance and operating chaacteristics of roadways.
What organizations use the Highway Performance Monitoring System?
State Transportation Departments (DOTs)
What do state DOTs use the Highway Performance Monitoring System for?
To determine where resources will be placed
What organizations collect and store License and Registration Data?
State DOTs
What is a limitation of License and Registration Data?
Raw data are not typically accessible.
Instead aggreagate data can be made available or published in traffic safety publications.
How often is data collected for the Nationwide Household Transportation Survey?
Every 5 to 7 years
What data elements does the Nationwide Household Transportation Survey collect?
- trip purpose
- travel mode
- travel time
- time of day
What can the Nationwide Household Transportation Survey be used for?
(In aggregate) to estimate hours traveled/mileage
What does socieodemographic/economic data include?
- Population statistics
- Age distribution
- Education level
- Unemployment rates
Where does sociodemographic/economic data come from?
Census data
What organization collects sociodemographic/economic data?
The Department of Labor Statistics
What is aggregate analysis?
Using numbers aggregated from information on individual records
What are two examples of aggregate analyses?
- Spatial (e.g. by geographic location)
- Temporal (e.g. comparing data from different dacades)
What is disaggregate analysis?
Using specific data elements on each individual record to assess association with crash outcome
What are examples of elements used in disaggreagate analysis?
- Age
- Gender
- Alcohol impairment
- Fatality rate
- Secondary task engagement AND age AND crash rate
What are the four basic tasks for analysis?
- Selection
- Aggregation
- Integration
- Normalization
Describe selection.
A subset of data for analysis based upon the research question
Describe aggregation.
Ways to further separate the sample in meaningful ways
What type of variables does aggregation work best for?
Categorical variables such as:
- age
- geographic location
How can aggregation be used to evaluate continous variables?
Split continous variable data into bins.
For speed data, have bins for different speed ranges.
What are examples of when integration is useful?
When you want to include functional classification of roadways or speed limit zones
To do this, integrate roadway information databases.
Describe normalization.
Determine a method to compare to other groups e.g. crash rate as calculated by:
- Vehicle-miles traveled (VMT) or
- Number of licensed drivers)
What are three analysis types?
- Frequency analysis
- Rate analysis
- Trend analysis
What are some examples of frequency analysis?
Total number of:
- crashes
- vehicles
- injured persons
What does frequency analysis provide?
A true, easy to understand, picture
What is a limitation of frequency analysis?
Difficuty comparing accross disparate groups (e.g. number of crashes in Boston vs. Blacksburg)
How is rate analysis conducted?
Divide frequency by a normalizing factor that is typically used to assess crash exposure
What are some examples of rate analysis metrics?
Crash rate per:
- Million vehicles in intersections
- Number of registered drivers in geographic regions
What is important to consider when comparing rate analyses accross groups?
That the numerator and denominator are defined the same
How is trend analysis conducted?
Calculate the mean value over a time period
What is important to consider with trend analysis?
Statistical analysis (e.g. linear regression) is needed to assess if a trend is statistically significant.
What factors must be considered when operationally defining a crash when using police accident reports?
- Police crash reports are only typically required when property damage exceeds $1-1.5k.
- Every police jurisdiction reports differently
What are some key things to consider in crash data analses
- Differences in documentation
- Which crashes require documentation
- What data elements in crash reports provide the desired information? Zip Code?
- Are there any subsequent research questions you are interested in?
- Inherent differences between cities
What are some examples of important differences between cities to consider in data analyses?
- socioeconomic
- tax base
- safety priorities
- police enforcement
Describe the Fatality Accident Reporting System (FARS).
- Formerly Fatal Accident Reporting System
- 1975 – current
Census of all police-reported crashes:
- that involve a motor vehicle traveling on a Trafficway customarily open to the public, and
- result in the death of at least one person (occupant of a vehicle or a non-motorist) within 30 days of the crash
Which three data collection systems comprise the National Automotive Sampling System?
- 1979 - 1986: Continuous Sampling System (CSS)
- 1988 - 2015: General Estimates System (GES)
- 1988 - 2015: Crashworthiness Data System (CDS)
What is included in the General Estimates System (GES)?
Police-reported crashes that involve:
- at least one motor vehicle traveling on a public Trafficway, and
- that result in property damage, injury, or death
Describe what is included in the Crashworthiness Data System (CDS)?
- Must involve a harmful event (property damage and/or personal injury) resulting from a crash, and
- must involve at least one towed passenger car or light truck or van in transport on a Trafficway
What replaced Nass/GES in 2016?
the Crash Report Sampling System (CRSS)
What replaced NASS/CDS in 2016 (pilot cases only)?
the Crash Investigation Sampling System (CISS).
Analytic files available since 2017.
Describe the Special Crash Investigations (SCI) data collection system.
- U.S. National Crash Data Collection System
- 1972 – present
- The most in-depth and detailed level of crash investigation data collected by NHTSA
- Intended to be an anecdotal data set useful for examining special crash circumstances or outcomes from an engineering perspective.
- Case Types include “Crash Avoidance Technology” and “Self-Driving Vehicle”.
Describe the Crash Injury Research and Engineering Network (CIREN).
- U.S. National Crash Data Collection System
- 1997 – present
- Crash investigations with case initiation through trauma centers;
- multidisciplinary (medical / engineering) evaluations focused on serious and disabling injuries.
Describe the Non-Traffic Surveillance (NTS) data collection system.
- National Crash Data Collection System
- formerly Not-in-Traffic Surveillance
- 2007 – present
- Estimated summaries for fatal and injured persons in:
- Motor vehicle crashes that occur off the public trafficways, and
- Nontraffic incidents such as a vehicle falling on a person underneath, hypothermia or hyperthermia, or an unintentional carbon monoxide poisoning inside the vehicle.
Describe the National Motor Vehicle Crash Causation Survey (NMVCSS).
- 2005 – 2007
- National survey of crashes involving light passenger vehicles
- Focuses on the factors related to pre-crash events.
Describe the Large Truck Crash Causation Study (LTCCS).
- 2001 – 2003
- National study to attempt to determine the critical events and associated factors that contribute to serious large truck crashes.
Describe the Pedestrian Crash Data Study (PCDS).
- U.S. National Crash Data Collection System
- Clinical study from six sites
- 521 Pedestrian-LPV traffic crashes
What are the four general categoriesof traffic crash and related data?
- epidemiological
- case-level
- naturalistic
- exposure
Describe Epidemiological data.
Larger data collections related to crashes, primarily based on official records
What is an example of epidemiological data?
Compilations from police reports with driver license / record information added
How is epidemiological data analysis typically conducted?
On aggregate data or large subsets thereof
What are some examples of U.S. epidemiological databases?
- FARS
- NASS-GES
- CRSS
Describe case-level data.
- Smaller collections from individual crashes that include:
- crash technician investigation
- data collection for more detailed data than available on police reports
- Analysis is typically conducted on:
- aggregate data
- large subsets of aggregate data
- case studies
How is case-level data analysis typically conducted?
Smaller collections from individual crashes that include crash technician investigation and data collection for more detailed data than available on police reports
Describe case studies.
detailed examination of a single case or a small number of cases typically selected based on very specific criteria
What are some example of case-level U.S. data?
- NASS-CDS
- CISS
- SCI
- CIREN
Describe naturalistic data
Unobtrusive continual acquisition of driver, vehicle, and environmental states
Describe naturalistic data analysis.
Unobtrusive continual acquisition of:
- driver
- vehicle
- environmental states
Analysis may summarize:
- aggregate driving or
- require some initial data reduction to summarize factors during short intervals surrounding crashes or
- other conditions of interest (e.g., near-crash, epoch, baseline), or
- may apply a case study approach
What are some examples of U.S. naturalistic data?
- 100-Car
- SHRP 2
Describe exposure data.
•Generally, aggregate measures used to create rates
What are some examples of exposure data elements?
- population
- licenced drivers
- registered vehicles
- vehicle miles traveled
What are some examples of U.S. exposure data?
- Vehicle Miles of Travel (FHWA)
- Annual light vehicle registrations (IHS/R.L. Polk NVPP)
In which years between 1995 and 2019 did the national annual vehicle miles traveled decrease compared to the year prior?
2008, 2009 and 2011
What year had the largest annual decrease in vehicle miles traveled compared to the prior year?
2020
Rank the degree of decrease in VMT from previous year for the five most notable decreases.
- 2020: 11%
- 1973: 2.5%
- 2008: 1.9%
- 1979: 1.0%
- 2011: 0.6%
- 1980: 0.1%
