FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION

FMCSA Contact: Albert Alvarez, MC-RTR, 202-385-2387

Individual Differences and the 

“High Risk” Commercial Driver

Background

There is a common belief in the trucking industry that, while most truck and

bus drivers are both conscientious and safe, a relatively small percentage of

commercial motor vehicle (CMV) drivers are associated with a significant and

inordinate percentage of the overall number of motor carrier crashes. These

drivers are considered to be "high risk" drivers, and the study summarized in

this Tech Brief focuses on these commercial drivers. This project explores

factors associated with "high risk drivers" and the means by which carriers

can reduce crash risk through various safety management practices and other

safety interventions. 

Study Design

Expert industry opinion was accessed through survey questionnaires on the

topic. Surveys were distributed to a random sample of safety managers

listed in the American Trucking Associations' fleet directory. A second survey

sample consisted of a group of "other experts"—those who are

professionally involved in CMV safety but are not fleet safety managers.

This group included former drivers and fleet managers, government

regulatory and enforcement personnel, industry trade association

representatives, and researchers. Of course, these are overlapping

categories, and most "other experts" indicated several different motor

carrier safety-related professional experience areas.

The results from these surveys were then compared to reviewed research

literature on the topic, with emphasis on the personal factors associated

with risk and carrier management approaches to reducing the problem. A

number of these factors potentially correlate with risk and may be the basis

for safety interventions to reduce risk.

Survey Method and Results

Two parallel survey forms were used—one for current CMV fleet safety

managers and the other for other experts in motor carrier safety. The

"safety manager" and "other expert" survey forms contained 50 and 48

questions, respectively. The surveys for "other experts" did not include

questions regarding CMV fleet information. These surveys were divided into

seven parts:

· Part 1: How Important is the Problem? Most respondents (59

percent Safety Managers, 54 percent Other Experts) felt that the worst 

10 percent of drivers were associated with 50 percent or more of fleet

crash risk.

· Part 2: Driver Factors Associated with Risk. Sixteen personal factors

were rated on a scale from "0" (no association) to "4" (strong

association) with regard to their strength of association with crash risk.

The factors, mean ratings (to the nearest tenth), and rankings are

presented in order of safety manager ranking in Table 1 (next page).

When there were ties in the mean ratings, rankings were determined by

looking at additional decimal places, which are not shown in the table.

Respondents in both groups rated personality traits such as

aggressiveness, impulsivity, and inattentiveness as having the highest

associations with risk. 

The goal of the Federal Motor

Carrier Safety Administration

(FMCSA) is to reduce the large

truck fatality rate by 41 percent

from 1996 to 2008. This reduction

translates into a rate of 1.65

fatalities in truck crashes per 100

million miles of truck travel.

FMCSA's Research and Technology

programs encompass a range of

issues and disciplines, all related to

motor carrier and bus safety and

security. FMCSA defines a

"research program" as any

systematic study directed toward

fuller scientific discovery,

knowledge, or understanding that

will improve safety, and reduce the

number and severity of commercial

motor vehicle crashes. Similarly, a

"technology program" defines

those programs that adopt,

develop, test, and/or deploy

innovative driver and/or vehicle

best practices, and technologies

that will improve safety and

reduce the number and severity of

commercial motor vehicle crashes. 

Currently, FMCSA's Office of

Research and Technology is

conducting programs in order to

produce safer drivers, improve

safety of commercial motor

vehicles, produce safer carriers,

advance safety through

information-based initiatives, and

improve security through safety

initiatives. The study described in

this Tech Brief was designed and

developed to support the FMCSA

Research and Technology strategic

objective to produce safer drivers.

The primary goals of this initiative

are to ensure that commercial

drivers are physically qualified,

trained to perform safely, and

mentally alert.

Office of Research and Technology

400 Virginia Ave, SW

Suite 600

Washington, DC 20024

Tech Brief
Table 1. Survey Results: Driver Factors Associated with Risk

DRIVER RISK FACTOR

SAFETY

MANAGERS OTHER EXPERTS

Mean

(0 - 4)

Rank

(of 16)

Mean

(0 - 4)

Rank

(of 16)

Aggressive/angry 3.4 1 3.4 3

Impatient/impulsive 3.4 2 3.5 1

Inattentive 3.4 3 3.4 2

Inexperienced (new CMV driver) 3.2 4 3.2 4

Unhappy with job/company 2.6 5 2.4 7

Young driver (less than 25) 2.5 6 3.1 5

Sleep apnea/other sleep disorder 2.4 7 2.9 6

Unhappy marriage/family problems 2.2 8 2.2 8

Debt or other financial problems 2.0 9 2.1 9

Heart or other medical condition 1.9 10 2.1 10

Dishonest 1.8 11 1.8 14

Older driver (60 or older) 1.7 12 1.9 12

New to company 1.6 13 2.0 11

Obese/overweight 1.4 14 1.7 15

Introverted/unsociable 1.3 15 1.1 16

Did not attend truck driving school 1.2 16 1.8 13

· Part 3: Driver Hiring Practices and Tools. The most frequently used, and highest

rated, hiring practices were checking the applicant Motor Vehicle Record (MVR),

contacting past employers, testing for alcohol and drugs (required by Federal regulation

for interstate carriers), and on-road driving tests. 

· Part 4: Driver Evaluation. "Continuous tracking of driver crashes, incidents, and

violations" was almost universally used by safety manager respondents and had the

highest-rated effectiveness for both respondent groups in terms of the four driver

evaluation practices presented. 

· Part 5: Driver Management. While reprimands (verbal and written) and manager

counseling were among the most-used methods for driver management, "monetary

rewards" received the highest effectiveness rating.

· Part 6: Comments. Three lines of blank space were provided on each form. 

· Part 7: Respondent Information.

Concepts of Crash Risk

Many interacting factors affect commercial driver crash involvement. The focus of this study

was on personal "constitutional" risk factors, or relatively enduring characteristics such as

health, physical skills, and some personality traits. At any given moment, however, a

number of other factors and influences are operative. A conceptualization of some major

interacting factors is shown in Figure 1 (next page).

Researchers have discovered that certain personal traits are related to the occurrence of a

vehicle crash—some drivers have a "differential crash risk." To the extent that this

differential crash risk is enduring, it probably reflects constitutional or other long-term

personal traits. This differential crash risk may also vary across time, reflecting chance

variation or changeable traits such as age, maturation, or learning by experience. 
Factors Related to Driver Risk

Many factors related to driver risk were

assessed in this literature review. The five

most cited include: 

· Age: For young CMV drivers, age is a

very strong personal factor that affects

crash involvement. In one statistical

study, young truck drivers (ages 18-21)

had moving violation rates that were

almost twice those of the middle-aged

drivers (30-49). Speeding above the

speed limit and unsafe speeds for

conditions were the two top violations

cited. In fact, young commercial drivers

were reported to be about 50 percent

more likely than middle-aged drivers to

be charged with a violation in a crash

(Blower 1996). In two-vehicle crashes

with light vehicles, the young truck

driver was twice as likely as the other

driver to be charged with a 

hazardous action or traffic violation, which is opposite the trend for large truck-light

vehicle crashes in general (FMCSA 2003). On the other hand, there appears to be no

major safety problem relating to older truck drivers. 

· Commercial Driving Experience: Experience driving a large truck or bus is clearly a

factor in driver safety. Not surprisingly, most motor carriers, particularly large carriers,

require prior commercial driving experience for applicants to be considered for hiring

(Stock 2001). 

· Sleep Disorder: Many studies agree that the relative risk of being involved in a crash

rises if the driver has a sleep disorder. The numbers given were anywhere from 3 to 14

times the normal risk.

· Impulsivity: Impulsivity, characterized by behavioral instability and an inability to

control impulses, including threatening behavior and violence, has been suggested to be

related to an increase in crash risk. A 1967 study found that both a high crash/other

accident group, and a high violation group scored higher on a measure of impulsivity

than those with a low number of crashes/other accidents and violations (Schuman, Peltz,

Ehrilch, and Seltzer, 1967). 

· Social Maladjustment and Aggressive/Angry Personalities: Various studies of the

personalities of high-crash drivers found these drivers to have negative social traits. For

example, when studying South African bus drivers with repeated crashes, Shaw and

Sichel (1961, 1971) described these individuals as being selfish, self-centered,

overconfident, resentful and bitter,

intolerant, and having antisocial attitudes

and criminal tendencies. 

Operational Safety Management

Methods

Based on the research review, the study

team believes that there are at least two

distinct ways to improve the safety

performance of a group of CMV drivers.

Figure 2 illustrates these. In the first

example (Figure 2a), the highest-risk

drivers are eliminated from the

distribution, as they are never hired, thus

"cutting off the tail" of the driver risk

distribution. This intervention would have

the effect of improving the performance

of the average driver of the group by

eliminating the greatest source of risk. In

the second example (Figure 2b), the safety

Figure 1. Major interacting factors affecting

commercial driver crash involvement.

Figure 2. Two conceptual mechanisms of

improvements to a group of drivers.

(a) “Cut off the tail” of the distribution—eliminate high-risk drivers.

(b) Move the distribution—reduce risk for all drivers.

Personal Constitutional Risk Factors

(health, physical skill, personality)

Frequency Highest Risk

“Across the board”

before

after

Frequency

Risk

Risk

Environmental Risk Factors

(weather, roadway)

Personal Situational Risk Factors

(hours driving, how much sleep the night before)

Behavior/Responses

Risks created by other

drivers and traffic

Vehicle Risk Factors

(brakes, tires)
Researchers

This study was performed at the

Virginia Tech Transportation

Institute, 3500 Transportation

Research Plaza, Blacksburg, VA

24061, by Ronald R. Knipling,

Erik C. B. Olsen, and Tammy D.

Prailey. Other contributors

included Linda N. Boyle at

University of Iowa Engineering,

Jeffrey S. Hickman at the Virginia

Tech Center for Applied Behavior

Systems, James S. York at Zurich

Services Corporation, and

Carmen Daecher at the Daecher

Consulting Group. Contract No.

DTMC 75-01-Z00105.

Key Words

Aggressive driving, crash, 

high risk drivers, commercial

motor vehicles, critical incident,

heavy truck, interaction,

naturalistic driving.

Notice

This Tech Brief is disseminated

under the sponsorship of the

Department of Transportation in

the interest of information

exchange. The Tech Brief

provides a synopsis of the

study's final publication. The

Tech Brief does not establish

policies or regulations, nor does

it imply USDOT endorsement of

the conclusions or

recommendations. The U.S.

Government assumes no liability

for its contents or their use.

Web Site

FMCSA Tech and Analysis Briefs

may be accessed at:

http://www.fmcsa.dot.gov. 

Technical Writer

Kirse Kelly

C2 Technologies, Inc.

September 2004

Publication No. FMCSA-RT-04-006

performance levels of all, or most, drivers in a group are improved through

effectiveintervention. The overall average safety level of the fleet improves

through "across the board" advancement. 

Based on the literature, and discussions with motor carriers, there are a

number of methods to reduce driver crash risks. These include:

· Systematic hiring,

· Driver selection tests,

· Driver performance evaluation,

· Driver training and counseling, 

· Driver rewards and punishment,

· Behavior-based safety,

· Driver self-management, and

· Driver termination.

Conclusions

The survey results and statistical findings presented in this report support the

view that commercial drivers differ greatly in their levels of crash risk, and that

a relatively small percentage of drivers (10-15 percent) account for a

disproportionate percentage of total fleet risk (30-50 percent). However, these

results lead to the realization of further research needs. The findings

presented in this report generally imply, but do not verify, that relative driver

risk, both general and specific, endures across long periods of time. In other

words, "risk" is, to some extent, a long-term personal trait, in addition to

being obviously related to specific situations and conditions. The various

personality traits and performance variables discussed in this report must now

be confirmed. One way that this can be done is through a systematic and

quantitative determination of the role that each of the many factors discussed

play in commercial driver risk. Another research need has to do with carrier

management strategies in working with the drivers who are more "accident

prone." This can be done through research in relation to all driver

management functions, including selection, evaluation, and management

intervention. With further research, motor carrier companies can learn how to

work with or avoid the "high risk" commercial driver, and the risk for all

drivers on the road can be reduced. 

References

Blower, D.F. The Accident Experience of Younger Truck Drivers. Final report

for the Trucking Research Institute and the Great Lakes Center for Truck and

Transit Research. May 1996.

Corsi, T.M. and Barnard, R.E. Best Highway Safety Practices: A Survey of the

Safest Motor Carriers About Safety Management Practices. Final report for

FMCSA Contract No. DTFH61-98-X-00006. 2003.

Schuman, S.H., Pelz, D.C., Ehrlien, N.J., and Seltzer, M.L. “Young male drivers:

Impulse expression, accidents and violations.” Journal of the American Medical

Association, 200, 1026-1030, 1967.

Shaw, L., and Sichel, H.S. Accident proneness. Oxford: Pergamon Press. 1971.

Shaw, L., and Sichel, H.S. “The reduction of traffic accidents in a transport

company by the determination of the accident liability of individual drivers.”

Traffic Safety Research Review, 5, 2-12, 1961.

Stock, D. I-95 Corridor Coalition Field Operational Test 10: Coordinated Safety

Management; Volume I: Best Practices in Motor Carrier Safety Management,

Final Report. August 2001.