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OCR for page 9
SECTION III--TYPE OF PROBLEM BEING ADDRESSED
EXHIBIT III-2
Fatal Speeding Crashes by Road Type and Speed Limit
Source: FARS data (NHTSA, 2006a)
Percentage of Total
Speeding-Related Speeding-Related
Road Type Speed Limit Traffic Fatalities Traffic Fatalities
Interstate Greater than 55 mph 1,373 10%
Less than or equal to 55 mph 371 3%
Non-Interstate Low (40 mph or less) 3,969 29%
High (45 mph or more) 5,793 43%
Unknown Unknown/No Statutory Limit 2,037 15%
Total 13,543 100%
Specific Attributes of the Problem
Much of the problem associated with speeding is behavioral. Unfortunately, there are cultural
barriers to producing safe driving behavior. Speed is marketed to car buyers. Cars today
can accelerate faster, reach higher speeds and handle more impressively than they could a
generation ago (Schneider, 2004). Advances in technology have allowed auto manufacturers
to produce efficient high-performance engines and lightweight parts (e.g., carbon fiber) that
result in high-performance vehicles. Speeding is a traffic violation that seems acceptable to
today's society. Exposure to high speeds, extreme driving and illegal racing in the media
promote the wrong message to drivers, especially younger drivers. When such messages are
combined with risks such as not wearing seatbelts, or driving under the influence of alcohol
or drugs, the result can be deadly. This section reviews crash data and other research in order
to better explain the nature of the speed- and speeding-related problems, and to help direct
highway agencies' safety improvement efforts.
Speed-related crashes, where speeding is not a contributing factor, are hard to identify in
crash databases. What characteristics of a crash identify speed as related to an improper
response to the driving environment? For example, crash data may identify high-accident
locations with relatively frequent run-off-road crashes where drivers were at or under the
speed limit, giving the impression that speed was not a factor. Yet, the characteristics and
pattern of the crashes could still indicate that speed was a contributing factor in the drivers'
improper response to the driving environment. Analysis of an agency's crash data is
an important step in the process for determining which safety improvements may be
appropriate. It is important that efforts are made to investigate the characteristics of the
crash data to identify all contributing factors so that the appropriate safety improvements
are implemented to address the crash problems.
Several trends observed in nationwide crash data are summarized in this section. A review of
characteristics of speeding-related crashes in an agency's jurisdiction can give insight into the
appropriate elements for a comprehensive program to reduce speeding-related and speed-
III-2
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SECTION III--TYPE OF PROBLEM BEING ADDRESSED
related fatalities. Characteristics of drivers, the roadway environment, and involved vehicles
should be analyzed. For example, analysis of age and gender can help identify a target audience
for public information and education campaigns. Review of other contributing factors can
indicate a benefit to combining programs; such as a seat belt safety education program that
includes information on speed reduction. A prevalence of pedestrian involvement in speeding-
related crashes may highlight a need for intersection lighting or pedestrian warning devices. An
analysis of an agency's crash data should be performed in order to determine appropriate
treatments that will address the specific safety concern. The strategies presented in this guide
are included based on the analysis of crash data discussed below.
Driver Characteristics
Driver characteristics such as gender, age, impairment at the time of a crash, and seatbelt
usage can contribute to the occurrence of crashes and the severity of injuries. Strategies to
address the crash factors linked to these characteristics are typically more education- or
enforcement-based than engineering-based, as these characteristics relate directly to driver
perception and abilities. Knowledge of characteristics of the drivers involved in crashes can
help an agency target the appropriate audience through the use of media outlets and formats
that market research has shown to be popular among a specific group. Understanding the
issues associated with the specific characteristics can help an agency identify strategies to
address the associated crash problems.
Driver Gender and Age
To develop an effective driver education program, agencies should identify the target
audience by examining crash data to determine if a particular type of driver is overrepresented
in speeding-related crashes. A review of FARS data shows that one of the most obvious trends
concerning these fatal collisions is the gender of the driver that was speeding.
39 percent of 15- to 20-year old male drivers involved in fatal collisions were speeding
compared with 26 percent of the female drivers of the same age group who were involved in
fatal collisions. Each successively older age group of both males and females had a smaller
percentage of speeding drivers when involved in a fatal crash, as illustrated in Exhibit III-3.
Even though a higher percentage of speeding drivers involved in a fatal crash are young,
middle-aged drivers still represent a large portion of speeding drivers involved in fatal
collisions. As illustrated above, though drivers under the age of 25 involved in fatal
collisions speed more than drivers of other age groups involved in fatal collisions, 21 percent
of male and 16 percent of female 35- to 44-year-old drivers involved in fatal collisions were
speeding. An agency with similar trends in its crash experience may choose to target young
male drivers in a public education campaign and in driver education courses, but education
outreach to middle-aged drivers should not be overlooked.
Driver Impairment
According to Traffic Safety Facts 2006--Speeding, approximately 41 percent of drivers with a
blood alcohol content (BAC) of at least 0.08 who were involved in fatal crashes were
speeding (NHTSA, 2006). Furthermore, 28 percent of the drivers 21 years or younger
involved in a fatal speeding-related collision were intoxicated with a BAC of at least
III-3
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SECTION III--TYPE OF PROBLEM BEING ADDRESSED
EXHIBIT III-3
Age and Gender of Speeding Drivers Involved in Fatal Collisions, 2006
Source: Traffic Safety Facts 2006-Speeding, NHTSA
45%
Male
40% Female
35%
30%
Percent Speeding
25%
20%
15%
10%
5%
0%
15-20 21-24 25-34 35-44 45-54 55-64 65-74 75+
Age
0.08. As shown in Exhibit III-4, as the evening progresses into night, the percentage of
alcohol- and speeding-related fatal collisions increases. The association between driver
impairment and speeding, and the increased incidence of fatalities associated with both
impairment and speeding at night, poses a level of risk that demonstrates a likely need for a
combination of strategies, such as public education and enforcement.
EXHIBIT III-4
Intoxicated and Speeding Drivers in Fatal Collisions by Time of Day (2006)
Source: Traffic Safety Facts 2006-Speeding, NHTSA
80%
Not Speeding Speeding
70%
Percent Alcohol Involvement
60%
50%
40%
30%
20%
10%
0%
6-9 am 9-12 am 12-3 pm 3-6 pm 6-9 pm 9-12 pm 12-3 am 3-6 am
Time of Day
III-4
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SECTION III--TYPE OF PROBLEM BEING ADDRESSED
For both speeding and non-speeding drivers involved in fatal crashes, the percentage of those
who had been drinking, with a BAC of 0.01 g/dL or higher, at the time the crash occurred
was higher at night than during the day. Between midnight and 3:00 a.m., 76 percent of
speeding drivers involved in fatal crashes had been drinking.
Occupant Protection
The availability and use of occupant restraints has a large influence on driver/passenger safety
in the event of a speeding-related collision. According to NHTSA (2006), "air bags combined
with lap/shoulder seatbelts, offer the most effective safety protection available today for pas-
senger vehicle occupant." Yet, also according to NHTSA, in 2006, of drivers age 21 and older
involved in fatal crashes, those who were not speeding were more likely to be wearing seatbelts
than those who were speeding at the time of the crash. For drivers age 21 and older, the percen-
tage of speeding drivers involved in fatal crashes who were using restraints at the time of the
crash was 43 percent, but 73 percent of non-speeding drivers in fatal crashes were restrained.
Young adults, ages 1620, generally exhibit lower voluntary seatbelt usage compliance than
other segments of the population (refer to Exhibit III-1 of NCHRP Report 500, Volume 11: A
Guide for Increasing Seatbelt Use, of this series). In 2006, only 45 percent of drivers under age
21 involved in a speeding-related fatal collision were wearing a seat belt at the time of the
crash, whereas 69 percent of drivers over age 21 involved in a (non-speeding) fatal collision
were wearing a seat belt. As young males also exhibit a tendency to drive at high speeds,
and their driving skills are less refined than older drivers' skills tend to be, the combination
of risky behaviors makes young males a particular target population for speeding-related
education strategies.
Environmental Characteristics
The roadway environment can contribute to the incidence of crashes by presenting drivers with
unexpected or unfamiliar situations that require a change in speed or other driving behavior.
Lighting and weather conditions are examples of conditions of the roadway environment that
can present additional challenges to drivers. Many times, a reduction in speed is needed to
safely navigate a section of roadway. Several strategies in this guide incorporate advance
warning of a need to reduce speeds, including for situations such as adverse weather.
Time of Day
Speeding-related fatal crashes were more likely to happen late at night and into early
morning. Between 10:00 p.m. and 3:00 a.m., each hour accounted for 5.5- to 6.5-percent of
daily (24 hour) speeding-related fatal crashes (see Exhibit III-5). This is higher than any
single hour during the day. Considering that traffic volumes decrease significantly late at
night and through the early morning, this indicates that speeding fatalities are
disproportionally high at night.
Weather Conditions
Speeding-related fatalities occurred most often under normal weather conditions. As shown
in Exhibits III-6 and III-7, rain is the most common condition under which speeding-related
III-5
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SECTION III--TYPE OF PROBLEM BEING ADDRESSED
EXHIBIT III-5
Time-of-Day Distribution for Speeding-Related Fatal Crashes
Source: FARS Data (NHTSA, 2006a)
Percent of Speeding-Related Fatal Crashes 7.0%
6.0%
5.0%
4.0%
3.0%
2.0%
1.0%
0.0%
12:00 AM 4:00 AM 8:00 AM 12:00 PM 4:00 PM 8:00 PM
Time of Day
fatalities occurred on high- and low-speed roadways. Rainy/snowy/icy weather was
present for 12% of the speeding-related fatalities on high-speed roadways, which suggests
that high speeds and wet road conditions afford a fatal combination.
As illustrated by Exhibits III-6 and III-7, 93 percent of all fatalities on low-speed roadways
and 86 percent of fatalities on high-speed roadways occurred under dry conditions. This
EXHIBIT III-6
Speeding-Related Fatalities on Low-Speed Roadways by Weather Conditions (2006)
Source: FARS Data (NHTSA, 2006a)
Wet; 6%
Snow/Slush; 0%
Ice/Frost; 0%
Sand/Dirt/Mud/Gravel; 1%
Water (Standing or Moving);
0%
Oil; 0%
Other; 0%
Unknown; 0%
Dry; 93%
III-6
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SECTION III--TYPE OF PROBLEM BEING ADDRESSED
EXHIBIT III-7
Speeding-Related Fatalities on High-Speed Roadways by Weather Conditions (2006)
Source: FARS Data (NHTSA, 2006a)
Snow/Slush; 1%
Wet; 9%
Ice/Frost; 2%
Sand/Dirt/Mud/Gravel; 2%
Water (Standing or Moving);
0%
Oil; 0%
Other; 0%
Unknown; 0%
Dry; 86%
indicates that adverse weather conditions are a larger problem on high-speed roadways than
they are on low-speed roadways.
Construction/Maintenance Zones
In 2006, 37 percent of fatal crashes that occurred in construction/maintenance zones
involved speeding (335 crashes). Of those crashes, 76 percent occurred on high-speed
roadways, which is indicative of noncompliance with reduced work zone speeds on high-
speed roadways.
Roadway Characteristics
Roadway elements can contribute to the speeds at which drivers feel comfortable as well as
present drivers with situations they may not expect.
Relevance of Road Design and Type
Speeding-related fatalities were found to occur primarily on two-way, undivided roadways
with 77 percent of speeding-related fatalities on low-speed roads and 62 percent of
speeding-related fatalities on high-speed roads occurring on this roadway type in 2006.
(Sixty-six percent of total speeding-related fatal crashes occurred on two-way, undivided
roadways.) (See Exhibits III-8 and III-9.) In 2006, speeding-related fatal crashes accounted
for 35 percent of all fatal crashes on low-speed roads, and 10 percent of all fatal crashes
regardless of road type. For the same time period, speeding-related fatal crashes accounted
for 30 percent of the high-speed road fatal crashes, and 21 percent of all fatal crashes.
III-7
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SECTION III--TYPE OF PROBLEM BEING ADDRESSED
EXHIBIT III-8
Speeding-Related Fatal Crashes on Low-Speed Roadways by Trafficway Flow (2006)
Source: FARS Data (NHTSA, 2006a)
Total Fatal
Speeding-Related Crashes on Total Fatal
Fatal Crashes on Percentage by Low-Speed Crashes on All
Trafficway Flow Low-Speed Roads Trafficway Flow Roads Roads
Two-Way Undivided 2,918 77% 27% 8%
TWLTL 182 5% 2% 0%
Divide without Barrier 416 11% 4% 1%
Divide with Barrier 161 4% 1% 0%
One-Way 56 1% 1% 0%
Ramp 57 1% 1% 0%
Unknown 21 1% 0% 0%
Total* 3,811 100% 35% 10%
*Sums may not total accurately because of rounding.
Whereas speeding is particularly problematic on low-speed roads, there are more deaths on
high-speed roads, as total travel (measured by VMT) is greater on high speed roadways.
Crash Type
Speeding-related fatalities occur primarily in single-vehicle crashes; 71 percent of speeding-
related fatalities on low-speed roads and 70 percent on high-speed roads occurred in this
manner of collision. (See Exhibits III-10 and III-11.) Right-angle collisions were the second
EXHIBIT III-9
Speeding-Related Fatal Crashes on High-Speed Roadways by Trafficway Flow (2006)
Source: FARS Data (NHTSA, 2006a)
Speeding-Related Total Fatal Total Fatal
Fatal Crashes on Percentage by Crashes on Crashes on
Trafficway Flow High-Speed Roads Trafficway Flow High-Speed Roads All Roads
Two-Way Undivided 4,916 62% 19% 13%
TWLTL 132 2% 0% 0%
Divide without Barrier 1,642 21% 6% 4%
Divide with Barrier 1,053 13% 4% 3%
One-Way 37 0% 0% 0%
Ramp 169 2% 1% 0%
Unknown 25 0% 0% 0%
Total* 7,974 100% 30% 21%
*Sums may not total accurately because of rounding.
III-8
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SECTION III--TYPE OF PROBLEM BEING ADDRESSED
EXHIBIT III-10
Speeding-Related Fatalities on Low-Speed Roadways by Manner of Collision (2006)
Source: FARS Data (NHTSA, 2006a)
F-to-S- Right Angle; 11% F-to-S- Opposite direction; 4%
Rear-end; 5%
Head-on; 5%
Sideswipe - Opposite
direction; 1%
Sideswipe - Same direction;
1%
F-to-S - Same direction; 1%
F-to-S- Unknown direction; 1%
Rear to Side; 0%
Other; 0%
Unknown; 0%
Rear to Rear; 0%
Single Vehicle Crash; 71%
EXHIBIT III-11
Speeding-Related Fatalities on High-Speed Roadways by Manner of Collision (2006)
Source: FARS Data (NHTSA, 2006a)
F-to-S- Right Angle; 6% Head-on; 6% F-to-S- Opposite direction; 5%
Rear-end; 10%
Sideswipe - Opposite
direction; 1%
Sideswipe - Same direction;
1%
F-to-S - Same direction; 1%
F-to-S- Unknown direction; 0%
Rear to Side; 0%
Other; 0%
Unknown; 0%
Rear to Rear; 0%
Single Vehicle Crash; 70%
III-9
