SUMMARY

It is estimated that 2.0 percent of drivers with commercial driver's licenses (CDLs) in 2003 used controlled substances, and 0.2 percent used alcohol (0.04 BAC) while performing their duties. On the basis of these findings, the Federal Motor Carrier Safety Administration (FMCSA) required testing rates for CDL drivers in calendar year 2004 remain at 50 percent for controlled substances and 10 percent for alcohol.

INTRODUCTION

FMCSA requires all motor carriers operating vehicles that must be driven by someone holding a CDL to have drug and alcohol testing programs. Such vehicles include trucks with gross combination weight ratings of more than 26,000 pounds, trucks carrying specific hazardous materials that require the vehicle to be placarded in accordance with FMCSA regulations, and buses designed to carry 16 or more passengers, including the driver. Carriers must randomly test a fixed percentage of their CDL drivers both for alcohol and for a specified set of five controlled substances.

In the case of alcohol, a driver is in violation of FMCSA regulations when the alcohol breath content is 0.02 grams per 210 liters of breath?equivalent to a blood alcohol content (BAC) of 0.02 grams per deciliter (g/dL). Drivers testing at this level are not permitted to perform safety-sensitive functions for at least 24 hours. In addition, drivers who test at the 0.04 g/dL level or higher must be evaluated by a substance abuse professional and undergo additional testing before being allowed to return to duty. For controlled substances, drivers are tested for marijuana, cocaine, opiates, amphetamines, and PCP. Table 1 shows the cutoff levels for identifying the use of these drugs, based on guidelines set by the Department of Health and Human Services.

Table 1. Cutoff Levels for Identifying Drug Use Among CDL Drivers

In addition to random testing, the FMCSA's drug and alcohol testing regulations require motor carriers to perform the following types of nonrandom testing: pre-employment testing (for controlled substances only, and only if the driver has not recently been in a drug and alcohol testing program); post-accident testing (if the crash involved a fatality, or if the truck driver received a citation in a crash involving a towaway or hospital-related injury); and testing of any driver who is suspected by a supervisor of using drugs or alcohol while at work. Table 2 summarizes these testing requirements.

Table 2. Motor Carrier Testing Requirements for CDL Drivers

REGULATORY HISTORY

METHODOLOGY FOR 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 their 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. Summary data for both random and nonrandom testing are collected from the motor carrier.

For the 2003 survey, 4,934 motor carriers were solicited, using the following six size-class strata:

• 1?19 CDL drivers
• 20?99 CDL drivers
• 100?249 CDL drivers
• 250?999 CDL drivers
• 1,000+ CDL drivers
• 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.

In the case of random testing, the sample can be viewed as a two-stage design, in which the motor carrier is selected in the first stage, and a subsample of its CDL drivers is selected (by the carrier) in the second stage. In the case of nonrandom testing, the sample represents a single-stage design in which each sampled motor carrier reports the results for all drivers subject to pre-employment, post-accident, and reasonable suspicion testing.

RESULTS

Random Testing

Summary data were provided by 1,318 motor carriers for controlled substance random testing (representing over 360,000 drivers), and 1,132 motor carriers provided data on random alcohol testing (representing 88,000 drivers). Survey estimates based on random testing are shown in Table 3, including estimates for previous years. As indicated in Table 3, the positive rate for controlled substance use in 2003 is estimated to be 2.0 percent with a standard error estimate of 0.3 percent. Based on these results, a 95 percent confidence interval on this estimate ranges from 1.3 to 2.7 percent. If the survey were replicated, one would expect 95 out of 100 confidence intervals to contain the true value for the positive rate. The positive rate for alcohol use in 2003 is estimated to be 0.2 percent with a standard error estimate of approximately 0.1 percent. These results suggest that a 95 percent confidence interval for the positive rate for alcohol ranges roughly from 0 percent to 0.3 percent.

Table 3. Estimated Positive Rates from Random Drug and Alcohol Testing: 2000-2003

The survey results suggest that the positive rates for controlled substance use and alcohol use have been approximately the same since 1997. (The differences in the year-to-year estimates are not statistically significant and cannot be shown to be a product of real differences in the population over time, and may result from statistical sampling error.) Furthermore, the 2003 survey estimates do not suggest that the required random testing rate for controlled substances or alcohol should be changed. For the controlled substance random testing rate to be lowered (now at 50 percent of CDL drivers), the controlled substance usage rate estimated from the survey must be less than 1 percent for two consecutive years, in accordance with FMCSA regulations. For random alcohol testing, the testing rate is currently at the minimum allowable by FMCSA (10 percent). In order for this rate to be raised, the alcohol usage rate from the survey must be estimated to be more than 0.5 percent in a given survey year.

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 many of the nonrandom testing categories, particularly for alcohol testing. In 2003, the largest number of nonrandom tests captured by the survey was in preemployment controlled substance testing, for which 414,968 tests were reported. Based on those cases, it is estimated that in 2003, 3.1 percent of CDL drivers undergoing pre-employment testing tested positive for controlled substances.

Publication Number: FMCSA-RI-05-034
Current as of May 2005

The goal of the Federal Motor Carrier Safety Administration (FMCSA) is to reduce the number and severity of large truck- and bus-involved crashes through more commercial motor vehicle and operator inspections and compliance reviews, stronger enforcement measures against violators, expedited completion of rulemaking proceedings, scientifically sound research, and effective CDL testing, recordkeeping, and sanctions.

The Office of Information Management develops and maintains systems for collecting and analyzing motor carrier data, and disseminates information on the motor carrier industry.

This Analysis Brief was produced by the Analysis Division in FMCSA's Office of Information Management. The division analyzes motor carrier data pertaining to crashes, inspections, compliance reviews, and drug and alcohol testing, and supports research on the effectiveness of FMCSA inspections and compliance review programs.

O I M
Office of Information Management
Federal Motor Carrier Safety Administration
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MCRI
Washington, DC 20590