Lessons Learned From 2016
U.S. Fatal Car Crash Data
Motor vehicle travel is a major means of transportation in the United States, yet for all its advantages, each year fatal motor vehicle crashes in the U.S. lead to an estimated societal burden of more than $230 billion from medical and other costs [1]. Motor vehicle crashes are also the leading cause of death for persons every age from 5 to 32 years old [2]. In this project, we deep dived into the fatal car crash records in the U.S. in year 2016, collected by National Highway Traffic Safety Administration (NHSTA) [3] and encoded using the government's Fatality Analysis Reporting System. By wielding this dataset and related research, we developed this report trying to thoroughly explore the top risk factors that are highly correlated to fatal motor vehicle crashes.
Anatomy of a Car Crash
Condition
Condition
Condition
Behavior
Behavior
Behavior
Delay
& Injuries
A motor vehicle crash results from a combination of factors related to the components of the system
comprising roads, the environment, vehicles and road users, and the way they interact.
Some factors, such as speeding and alcohol or drug impaired driving, contribute to the occurrence of a collision and are therefore part of crash causation. Other factors, such as old vehicles and unused restraints systems, aggravate the effects of the collision and thus contribute to trauma severity.
Some
causes are immediate, but they may be
underpinned by medium-term and long-term
structural causes. Identifying the top risk factors that contribute to fatal motor vehicle crashes is important in developing
interventions that can reduce the risks associated with those factors.
Time of Crash
Hover on circles to view number of crashes by month and hour.
Methodology: The size and color indicates crash frequency during the given hour in the given month.
It can be seen that fatal crashes also tend to happen more frequently in winter seasons, e.g. November and Decemeber, where adverse weather conditions (e.g. snow on the East Coast and rain on the West Coast) increase risks. Click on UNDER ADVERSE WEATHER tab to see how adverse weathers impacts fatal crash count.
Note that we do not observe the same high frequency during rush hours in the morning. We further explored the light condition that existed at the time of the crash and see how it might have impacted fatalities. Click on UNDER BAD LIGHTING tab to see more details.
Hover on circles to view number of crashes occurred under bad lighting conditions by month and hour.
Methodology: This plot highlights fatal crashes that happened in a dark and unlighted environment.
Hover on circles to view number of crashes under adverse weather by month and hour.
Methodology: Weathers other than clear or cloudy (i.e. rain, sleet, snow, fog, severe crosswinds, or blowing snow/sand/debris) are considered as adverse weathers.
Weather Condition
Approximately 21% of all vehicle crashes are weather-related and on average, nearly 5,000 people are killed in weather-related crashes each year (source: Ten-year averages from 2007 to 2016 analyzed by Booz Allen Hamilton, based on NHTSA data). Weather acts through visibility impairments, precipitation, high winds, and temperature extremes to affect driver capabilities, vehicle performance (i.e. traction, stability and maneuverability), pavement friction, roadway infrastructure, crash risk, traffic flow, and agency productivity. See NHSTA's summary of how weather impacts various weather events on roadways, traffic flow, and operational decisions.
Hover on circles to view fatal crash counts by states.
Methodology: Occurrence of various adverse weather conditions that existed at the time of the crash is counted for each state. Weathers other than clear or cloudy (i.e., rain, sleet, snow, fog, severe crosswinds, or blowing snow/sand/debris) are considered as adverse weathers.
Road Condition
The Most Dangerous Highway
Hover on map to view details about county, population and fatalities per 100,000 population.
Methodology: The fatality rate is computed as {[total fatalities in car accidents in year 2016] / [county population]} × 100%. County population data source.
One notable outlier from this map is Loving, Texas, a sparsely populated county with a soaring fatality rate of 3.158%. The culprit is one West Texas highway that is notorious for being dangerous - Highway 285, which runs from New Mexico right on through the small town of Fort Stockton. According to the New Mexico Department of Transportation, there were another three fatal crashes from the Texas state line to Loving in 2017. "Because there are so many trucks coming off the side roads and you know they don't see everybody and they will just pull off," said Sherrif Cliff Harris,"Or pull right in front of people sometimes." It was said the construction zones in Fort Stockton "are not going anywhere anytime soon."
Driver Behavior
Driver Circumstances
Hover on bars to view crash counts by circumstances.
Methodology: Circumstances that may have contributed to a crash include distraction, driver's physical impairment, alcohol/drug influence, and impediments to the driver's visual field.
Alcohol and drugs usage is highly risky for both drivers and pedestrains (click on tabs to see how they correlate to fatality risk). Avoid alcohol and drugs when walking and driving; they impair your judgment and coordination.
Speeding
Speeding endangers everyone on the road: According to NHSTA, for more than two decades, speeding has been involved in approximately one-third of all motor vehicle fatalities. In 2016,
- Speeding killed 10,111 people, accounting for more than a quarter (27%) of all traffic fatalities.
- 37% percent of all speeding drivers were alcohol-impaired in fatal crashes.
How much does speeding have an impact on fatality risk of the vehicle occupants?
Hover on circles to view crash counts and average overspeeding amount (MPH) for the selected overspeed range.
Methodology: The overspeeding amount of a vehicle is computed as {[vehicle travel speed] - [road speed limit]} at the time of crash. The average fatality percentage for a overspeeding range is computed as {[fatality in vehicle] / [all occupants in vehicle]} × 100% averaged over all vehicles involved in fatal crashes in that overspeeding range at the time of crash.
Speeding tickets are the most commonly used tool to deter speeders, but do they actually have an impact on driver's behaviors (and reducing car crashes related to speeding)?
Hover on bars to view details.
Methodology: This visualization relates the vehicle's overspeeding amount at the time of crash to the driver’s past speeding convictions. We trace the change in ratio of drivers involved in fatal crashes by the number of previous (within five years from the crash date) speeding convictions of the driver.
Passenger Behavior
Restraint System Use
Of the 23,714 passenger vehicle occupants killed in 2016, there were 11,282 (48%) who were restrained and 10,428 (44%) who were unrestrained at the time of the crashes. Restraint use was not known for the remaining 2,004 (8%) of the occupants. For passenger vehicle occupants involved in fatal crashes in 2016, nearly half of those who were killed were unrestrained in the crash, compared to only 14 percent of those that survived.
Hover on bars to view injury counts.
Methodology: The data describes restraint usage of passengers of a motor vehicle in-transport.
Hover on bars to view injury counts.
Methodology: The ejection scenario describes the ejection status and degree of ejection for this person, excluding motorcycle occupants.
Seating Position
Among all vehicle occupants, people riding on vehicle exterior have the highest fatality rate, followed by passengers sitting in cargo areas or trailing unit, a result from lacking safety protection measures. Inside the vehicle, seats in the front row (Front Seat, Second Seat positions) are shown to be more dangerous than seats in the back row (Third Seat, Fourth Seat positions).
Hover on bars to view injury counts.
Pedestrian Behavior
In 2016,
• 5,987 pedestrians were
killed in traffic crashes,
accounting for 16% of all
traffic fatalities.
• On average, a pedestrian was
killed in
traffic crashes nearly every 1.5 hours.
Hover on bars to view injury counts.
Below we show how the number of fatal crashes correlate to pedestrian actions immediately prior to the crash and how the actions relate to the orientation of their collision with respect to the striking vehicle.
Hover on circles to view details.
Data show that far more people involved in fatal crashes when dealing with disabled vehicles (see recounts of such incidents here, here and
here).
Do you know what to do if your vehicle becomes disabled on a highway?
Experts offered advise on how to remain safe during a roadside emergency.
"You are better protected in the car than anywhere else,"
said Cathleen Lewis, director of Public Affairs and Government Relations for the
Northeast division of AAA.
"If possible, get off the highway before stopping," said Lt. Theodore Schafer of the New Jersey State Police.
"Is it worth you protecting the rim on your car and pulling over in a dangerous spot versus possibly damaging the rim and making yourself safe? Try to get far enough out of the way and off the main roads so that you won’t be an obstacle for other cars."
Both experts agree that the best thing to do is call 911. Don’t be shy about it.
"There seems to be a misconception that we will be upset with you if you call 911," Schafer said, "If your car is broken down on the side of the road to us that constitutes an emergency that requires assistance, so absolutely call 911."
Vehicle Condition
We investigated how passenger vehicle occupant fatality correlates to various vehicle conditions in fatal crashes.
Vehicle Model Year
Hover on circles to view details.
Methodology: The average fatality percentage for a vehicle model year is computed as {[fatality in vehicle] / [all occupants in vehicle]} × 100% averaged over all vehicles of that model year involved in fatal car crashes.
Vehicle Age
Hover on circles to view details.
Methodology: The age of a vehicle is measured by subtracting the vehicle model year from the calendar year at the time of the crash (vehicle whose age was calculated to be -1 was recoded to be age 0).
The average fatality percentage for a vehicle age is computed as {[fatality in vehicle] / [all occupants in vehicle]} × 100% averaged over all vehicles of that vehicle age involved in fatal car crashes.
The analysis shows that among all passenger vehicle (passenger cars, SUVs, pickup trucks or vans) occupants involved in a fatal crash, the proportion who were fatally injured increases with vehicle age, i.e., the proportion was higher among occupants of older vehicles as compared to the occupants of newer vehicles. Also, the proportion of occupants who were fatally injured was higher among occupants of older model year vehicles as compared to the occupants of newer model year vehicles.
The improved quality of cars is a bit of a double-edged
sword when it comes to the age issue.
As cars get better on multiple fronts, such as
safety technology and crashworthiness, they also
become more reliable and longer lasting, leading to
Americans driving cars until they're much older and
pushing the average age of a car in the U.S. up to
11.6 years at last count. Despite these gains in car quality,
the older a car gets, the less reliable and less safe it becomes.
NHTSA has released a shopping guide
to help consumers make sense of the myriad vehicle safety and driver assistance
systems available on modern cars.
Airbag Deployment
Hover on bars to view details.
It is important, however, to follow guidance on how to safely position yourself and your passengers, as well as young ones in car seats and booster seats to prevent injury from air bags in a crash. Generally, when there is a moderate to severe crash, a signal is sent from the air bag system's electronic control unit to inflate the air bag within the blink of an eye (less than 1/20th of a second). Because air bags deploy very rapidly, serious or sometimes fatal injuries can occur if the driver or passenger is too close to – or comes in direct contact with – the air bag when it first begins to deploy. Side-impact air bags inflate even more quickly since there is less space between the driver or passengers and the striking object, whether the interior of the vehicle, another vehicle, a tree, or a pole. See more info on airbag-related fatality here, here, and here.
Vehicle Occupant Satety Tips:
- Sit as far back from the steering wheel or dashboard as possible and using seat belts help prevent drivers and passengers from being "too close" to a deploying frontal air bag. This is why rear-facing car seats should not be placed in front of an active air bag, and children under 13 should be seated in the back seat.
- Always buckle your seat belt. The seat belt is the single most effective vehicle safety technology. Air bags are supplemental protection and are designed to work best in combination with seat belts.
Vehicle Body Type
We have also studied which vehicle body types render their occupants vulnerable to fatality risk in road traffic crashes.
It was observed that fatality risk varies widely based on vehicle body types, and notably, motorcycles (of all types) and snowmobiles occupants suffer higher fatality risk by a large margin. Trucks, vans, and buses have some of the lowest fatalities.
Click here to compare how different vehicle body types relate to fatality risk below.
Rescue Delay
Response Time in Urban Area
Hover on bars to view average response time in urban area of each state.
Methodology: "crash2notification" tracks the time from the crash occurred to the emergency medical service was notified. "notification2arrival" tracks how long it took for the emergence medical service to arrive on the crash scene. "arrival2hospital" tracks how long it took for the emergence medical service to transport victims of the crash to the treatment facility. The time is averaged over all crashes that happened in the urban area of the given state.
Response Time in Rural Area
Hover on bars to view average response time in rural area of each state.
Methodology: The time is averaged over all crashes that happened in the rural area of the given state.
Response Time v.s. Emergency Medical Service (EMS) Facilities
Hover on circles to view details.
Methodology: By combining Homeland Infrastructure Foundation-Level Data (HIFLD) and U.S. Census Bureau data, we further relate response time to the per-capita number of emergency medical service stations which provide ambulances.
Further Exploration
Analyzing and visualizing the NHSTA traffic record dataset has been a challenging task:
the dataset consists of 20 data tables which collectively describe over 400
known attributes of 34,619 fatal motor vehicle crashes. Furthermore,
as a motor vehicle crash usually results from a combination of factors including
vehicles, road users, environment, and the way they interact, it possess
challenges to underpin their individual influences in road traffic fatalities.
To overcome this shortcoming, we have built a predictive model using machine learning, based on our analysis, for predicting
a person's fatality risk in a road traffic crash scenario given input features
about this person, such as alcohol usage, seating position, person type and so on. We encourage interested readers
to play with our model
and see how much changing a factor while keeping other variables controlled
will affect fatality risk quantitatively.
Due to the sheer volume of data present in the NHSTA dataset, our analysis is likely to
have overlooked some risk factors contributing to fatal car crashes.
Interested readers are encouraged to use the interactive map of the U.S. below to learn about case details of the fatal car crashes occurred in 2016 and filter records by selected attributes
(explore this map in fullscreen mode
).