FEDERAL HIGHWAY ADMINISTRATION • OFFICE OF MOTOR CARRIERS

FHWA Contact: Richard Gruberg, HIA-20, (202) 366-2959

Drug and Alcohol Testing Survey

In 1995, it is estimated that 2.8 percent of drivers with a commercial driver’s

license (CDL drivers) tested positive for controlled substance use, and 0.1 

percent tested positive for alcohol use. In 1996, it is estimated that 2.2 percent

of CDL drivers tested positive for controlled substances and 0.2 percent for

alcohol use. On the basis of these findings, the alcohol testing rate for motor

carriers was lowered from 25 percent to 10 percent for all motor carriers for

calendar year 1998.

Introduction

The Federal Highway Administration (FHWA) requires all motor carriers employing 

drivers holding CDLs to have drug and alcohol testing programs. Carriers must randomly

test a fixed percentage of their CDL drivers each year for both alcohol (for which 10 

percent of all drivers must be tested annually) and for a specified set of controlled substances (for which 50 percent of all drivers must be tested annually).

In the case of alcohol, a driver is considered to have tested positive if the blood alcohol

content is 0.04 grams per deciliter or higher. For controlled substances, drivers are tested

for marijuana, cocaine, opiates, amphetamines, and PCP. The cutoff levels for identifying

the use of these drugs are based on guidelines set by the Department of Health and

Human Services, as shown in table 1.

In addition to random testing, the FHWA’s drug and alcohol testing regulations require

motor carriers to perform the following types of nonrandom testing: pre-employment

testing (if the driver has not recently been in a drug and alcohol testing program); postaccident testing (if the crash involved a fatality, or if the crash involved both a towaway

or hospital-related injury and the truck driver received a citation); and testing of any 

driver who is suspected by a supervisor of using drugs or alcohol while at work. Table 2

presents the testing requirements for CDL drivers. 

Motor carriers must make their annual drug and alcohol summary data available to the

FHWA upon request. The summary information includes the number of drivers tested

and the number who tested positive for each test category.

Each year, the FHWA conducts a survey to estimate drug and alcohol usage rates for CDL

drivers, based on a statistical sample of the summary information collected from motor

carriers. The estimates from this survey are used to evaluate FHWA required random testing rates (the percentage of employees that need to be tested annually by each carrier)

for both alcohol and controlled substances.

Background

FHWA drug testing requirements for motor carriers began in 1994, when all U.S.-

domiciled motor carriers operating motor vehicles in interstate commerce were required

to implement controlled substance testing programs. In 1995, the requirements were

expanded to include large intrastate carriers (50 or more CDL drivers). In the same year,

Analysis Brief

The vision of the Office of

Motor Carriers (OMC) is to

help move people, goods, and

commercial motor vehicles on

our Nation’s highways in the

most efficient, economical,

and crash-free manner 

possible. The goal of OMC’s

Office of Information Analysis

is to develop and maintain

systems for collecting and

analyzing motor carrier data

and to disseminate information concerning the motor 

carrier industry.

The Analysis Division analyzes

motor carrier data pertaining

to crashes, inspections, compliance reviews, and drug and

alcohol testing; supports

research on the effectiveness

of OMC programs, such as

roadside inspections and 

compliance reviews; and 

helps States to comply with

Federal size and weight

statutes for trucks.

Office of Motor Carrier Research

and Standards

400 Seventh Street, SW

HCS-30; Room 3107

Washington, DC 20590
all large carriers (both interstate and intrastate) were

first required to begin implementing alcohol testing

programs. Beginning in 1996, all motor carriers operating in the United States (both U.S.-domiciled and 

foreign-based) were required to have both controlled

substance and alcohol testing programs in place.

Methodology — Data Collection

Each year, eligible motor carriers are selected into the

survey by means of a stratified random sample. In this

approach, all eligible motor carriers are classified

before sample selection into size class groupings (or

strata), based on the carrier’s number of CDL drivers. A

random sample of carriers is then selected in each size

class stratum. Stratification helps to ensure that the

sample is representative and also increases the precision of the estimates. Both random and nonrandom

testing data are collected from the motor carrier.

For this survey, six size class strata are used: 

• 1 – 19 CDL drivers, 

• 20 – 49 CDL drivers, 

• 50 – 99 CDL drivers, 

• 100 – 999 CDL drivers, 

• 1,000 or more CDL drivers, and 

• size unknown. 

To maximize the precision of the survey estimates, all

eligible motor carriers from the largest size class stratum (1,000 or more CDL drivers) are selected into the

sample with certainty.

Because each sampled motor carrier randomly tests

only a fraction of its CDL drivers, the sample, in the

case of random testing, represents a two-stage design

in which the motor carrier is selected in the first stage

and a subsample of its drivers is selected in the second.

On the other hand, in the case of nonrandom testing,

the sample represents a single-stage design in which

each sampled motor carrier reports the results of all

the nonrandom tests it was required to perform during

the calendar year.

Results

Random Testing

For the 1994 survey, 1,048 motor carriers were selected

into the sample. Of those carriers, 547 provided usable

random testing data to the FHWA for controlled substances. (Alcohol testing was not yet required in 1994;

hence, no data for alcohol were provided for that year.)

In 1995, 1,747 motor carriers were selected. Of those,

648 provided random testing data for controlled 

substances, and 265 provided random testing data for

alcohol. (Note that in 1995 only carriers with 50 or

more CDL drivers were required to perform random

alcohol testing.)

For the 1996 survey, 3,396 motor carriers were 

selected. Of those, 1,147 provided data for controlled

substance random testing and 1,004 provided data for

alcohol testing. Survey estimates based on random

testing for each year are shown in table 3.

As indicated in the table, the positive rate for controlled substance use in 1994 is estimated to be 2.6

percent with a standard error of 1.0 percent. Based on

these results, a 95 percent confidence interval on this

estimate ranges from 0.64 to 0.56 percent (0.026 ±

1.96 x 0.01). Thus, if the survey had been replicated,

one would have expected the estimate to have fallen

within this range in 95 out of 100 replications.

The positive rate for controlled substance use in 1995

is estimated to be 2.8 percent of all CDL drivers, with

an estimated standard error of 0.5 percent. Based on

these results, a 95 percent confidence interval for this

estimate ranges from 1.8 percent to 3.8 percent (0.028

± 1.96 x 0.005).

The positive rate for alcohol use in 1995 based on 

random testing is estimated at 0.14 percent, with a

standard error of 0.02 percent. Based on this level of

precision, the 95 percent confidence interval for the

estimate ranges from 0.10 percent to 0.18 percent

(.0014 ±1.96 x .0002).

Table 1. 

Cutoff Levels for Identifying Drug Use 

Among CDL Drivers

Substance Cutoff Levels

Alcohol .04 gr / deciliter

Marijuana 15 ng / ml

Cocaine 150 ng / ml

Opiates (morphine, codeine) 300 ng / ml

Amphetamines

amphetamine 500 ng / ml

methamphetamine 500 ng / ml*

Phencyclidine (PCP) 25 ng / ml

*Specimen must also contain amphetamine at 200 ng / ml or higher.
For 1996, the positive rate for controlled substance use

is estimated to be 2.2 percent, with a 95 percent confidence interval ranging from 1.4 percent to 3.0 percent

(0.022 ± 1.96 x 0.004). The estimated positive rate for

alcohol use in 1996 is approximately 0.2 percent, with

a 95 percent confidence interval ranging from 0.12

percent to 0.24 percent.

Although the positive rates for alcohol usage are

extremely low for both 1995 and 1996, it should be

noted that the 1996 estimate incorporates data from

all carriers, whereas the 1995 estimate for alcohol use

incorporates data only from carriers that have 50 or

more employees.

Based on the results of the 1996 survey, the alcohol

random testing rate for motor carriers was lowered

from 25 percent to 10 percent of each carrier’s CDL 

drivers for calendar year 1998, in accordance with

Federal regulations. These regulations stipulate that

when the required testing rate for alcohol is 25 percent or higher, the FHWA may lower the testing rate

to 10 percent if the positive rate for alcohol usage

among CDL drivers is estimated from the survey to be

less than 0.5 percent for 2 consecutive years.

The required random testing rate for controlled substances did not change for calendar year 1998 and

remains at 50 percent of each carrier’s CDL drivers. In

order for this rate to be lowered, the controlled substance usage rate estimated from the survey would

have to be less than 1 percent for 2 consecutive years.

Nonrandom Testing

In the case of nonrandom testing, the number of tested drivers evaluated by the survey each year has been

too small to produce reliable estimates of a usage rate

for most of the nonrandom testing categories. In 1996,

the largest number of nonrandom tests captured by

the survey was in pre-employment controlled substance testing, where 852 cases were considered. On

the basis of those cases, it is estimated that in 1996, 

2.4 percent of CDL drivers undergoing pre-employment

testing tested positive for controlled substances. 

Table 2. 

Motor Carrier Testing Requirements for CDL Drivers

Type of Test Drivers to be Tested

Random Controlled Substance Testing 50% of all company CDL drivers per year.*

Random Alcohol Testing 10% of all company CDL drivers per year.*

Post Accident Testing

Fatal Crashes All CDL drivers involved.

Nonfatal Crashes CDL drivers receiving citations, if crash involves 

towaway or hospital-related injury.

Reasonable Suspicion Testing Any CDL driver suspected by supervisor of using 

alcohol or controlled substances on the job.

*If random testing is conducted through a consortium, the number of drivers to be tested may be based on the total number of drivers covered by

the consortium, rather than the total number of drivers in the company.

Table 3. 

Estimated Positive Rates from Random Drug and Alcohol Testing, 1994, 1995, and 1996

1994 1995 1996

Estimated Estimated Estimated

Positive Standard Positive Standard Positive Standard

Areas of Testing Rate Error Rate Error Rate Error

Controlled Substances 2.6% 1.0% 2.8% 0.5% 2.2% 0.4%

Alcohol NA NA 0.14% 0.02% 0.18% 0.03%

Source: Federal Highway Administration, Office of Motor Carriers NA = not available
Researcher

This analysis was performed

internally by OMC’s Office of

Information Analysis, Analysis

Division, HIA-20, Contact:

Richard Gruberg, (202) 366-

2959.

Distribution

This Analysis Brief is being 

distributed according to a

standard distribution. Direct

distribution is being made to

the Regions and Divisions.

Availability

The study final report (PB97-

124705) is available from the

National Technical Information

Service, Telephone: (703) 605-

6000.

Key Words

motor carriers, CDL drivers,

alcohol usage, controlled 

substance usage, positive rate,

testing rate, random testing,

nonrandom testing, sample

survey.

Notice

This Analysis Brief is disseminated under the sponsorship

of the Department of

Transportation in the interest

of information exchange. 

The brief does not establish

policies or regulations. The

U.S. Government assumes no 

liability for its contents or

their use.

September 1998

Publication No. FHWA-MCRT-98-003