DOT Drug and Alcohol Testing for Traffic Control Crews: Who Is in the Program and What It Requires

Most traffic control owners know there are federal drug and alcohol testing rules for truck drivers. Fewer are sure which of their own people are in them.

The uncertainty is understandable. A traffic control company has flaggers on foot, crew leads in pickups, drivers in attenuator trucks and somebody pulling a message sign trailer. Some of those jobs are inside the federal program and some are not, and the dividing line is the vehicle, not the job title.

This post explains how the Federal Motor Carrier Safety Administration's rule at 49 CFR Part 382 defines who is covered, what tests it requires, what the Clearinghouse obligations are, and what records to keep. It paraphrases the regulation and links each section. It is general information, not legal advice, and it does not tell you whether a particular driver or vehicle in your fleet is covered. Requirements vary with your operation, and states add their own rules. Verify with FMCSA, your state agency or a qualified compliance adviser.

Our broader post on FMCSA requirements for traffic control fleets covers registration, driver files and the other motor carrier obligations. This one stays on testing.

Why the rule exists

Heavy trucks are a large part of the work zone crash picture. FHWA's work zone facts page reports that commercial motor vehicles were involved in 246 fatal work zone crashes in 2022, or 30 percent of the 821 fatal work zone crashes that year.

Traffic control companies put heavy vehicles in the most exposed position there is. A shadow truck with an attenuator is placed to be hit. Its driver sits in a live lane for a shift. The testing rules treat that driver the way they treat any other commercial driver.

Who the rule covers

The applicability section, 49 CFR 382.103, says the part applies to every person, and to all employers of such persons, who operate a commercial motor vehicle in commerce in any state and are subject to the commercial driver's license requirements of Part 383.

So the test has two parts. Is the vehicle a commercial motor vehicle as Part 383 defines it? And is the person operating it subject to CDL requirements?

The definition is at 49 CFR 383.5. In summary, a commercial motor vehicle for CDL purposes is a vehicle or combination used in commerce to transport passengers or property that is one of the following:

Group	Definition in 49 CFR 383.5
Combination vehicle	Gross combination weight rating or gross combination weight of 26,001 pounds or more, inclusive of a towed unit with a gross vehicle weight rating or gross vehicle weight of more than 10,000 pounds
Heavy straight vehicle	Gross vehicle weight rating or gross vehicle weight of 26,001 pounds or more
Small vehicle	Designed to transport 16 or more passengers including the driver, or used to transport hazardous materials as defined in that section

That table explains most of what you see in a traffic control fleet.

• A heavy straight truck carrying a truck-mounted attenuator may be rated at or above 26,001 pounds. Many are. Some lighter attenuator trucks are rated below it.
• A pickup towing a message sign or arrow board trailer is usually well under the combination threshold.
• A medium truck towing a heavy equipment trailer can cross the combination threshold when the trailer is rated over 10,000 pounds and the combined rating reaches 26,001 pounds.
• A crew van is covered by the passenger branch only if it is designed for 16 or more people including the driver.

The rating plate on the door jamb and the trailer tongue is where the answer starts. Read the ratings, not the scale weight on a light day, because the definition uses the greater of the rating and the actual weight. If a vehicle is close to a threshold, ask your state licensing agency or a compliance adviser. See truck-mounted attenuators explained for the equipment itself.

One more point from the applicability section catches small companies. An owner who also drives is both employer and driver, and has to meet both sets of requirements. The section says an employer who employs only himself or herself as a driver must implement a random testing program of two or more covered employees in the selection pool, which in practice is done by joining a consortium.

What about flaggers and crew members on foot?

A flagger who does not operate a commercial motor vehicle is not a driver under Part 382 as the applicability section is written. The same goes for a laborer setting cones from the back of a truck someone else drives.

Three caveats.

People change roles. The flagger who is asked to move the attenuator truck "just this once" is, for that trip, operating a commercial motor vehicle. If the truck requires a CDL, the person driving it needs one and needs to be in the program first.

Other parties can require testing. A prime contractor, a utility or a public owner can require a drug-free workplace policy as a condition of the work. That is a contract term, separate from the federal rule.

Company policies are governed by state law. An employer can choose to test employees who are outside the DOT program. The rules for that, including what is permitted and how results are handled, come from state law and differ widely. DOT tests and company-policy tests are also kept separate administratively. Get advice from an employment attorney before writing a policy.

"Safety-sensitive function" is wider than driving

Several requirements turn on whether a driver is performing a safety-sensitive function. The definition at 49 CFR 382.107 is broader than time behind the wheel. It covers all time from when a driver begins work or is required to be in readiness to work until relieved from work and all responsibility for performing work.

The listed examples include time waiting to be dispatched, time inspecting or servicing a commercial motor vehicle, time at the driving controls, time loading or unloading or supervising it, and time attending a disabled vehicle.

For a traffic control driver, that means the morning in the yard doing the walk-around and loading drums counts, as does the shift parked in the closure.

The tests

Part 382 requires testing in six situations. Return-to-duty and follow-up testing happen after a violation. The other four apply to everyone in the program.

Pre-employment

Under 49 CFR 382.301, a driver undergoes testing for controlled substances before the first time the driver performs safety-sensitive functions for an employer. The employer shall not allow the driver to perform those functions until it has received a verified negative result.

There is an exception for a driver who has participated in a qualifying testing program within the previous 30 days, subject to conditions listed in the section, including having been tested within the past 6 months or having been in a random program for the previous 12 months. The employer has to verify the details.

The practical consequence is a waiting period in hiring. A new CDL driver cannot start in the truck on the day of the offer. Many companies start the new hire on non-driving work, such as flagging or yard duty, until the result is back.

Post-accident

49 CFR 382.303 sets out when a test follows an occurrence involving a commercial motor vehicle on a public road. In summary:

Type of accident	Citation issued to the CMV driver	Test required
Human fatality	Yes or no	Yes
Bodily injury with immediate medical treatment away from the scene	Yes	Yes
Bodily injury with immediate medical treatment away from the scene	No	No
Disabling damage to any vehicle requiring a tow	Yes	Yes
Disabling damage to any vehicle requiring a tow	No	No

Timing matters. If an alcohol test is not administered within two hours of the accident, the employer prepares a record stating why. At eight hours the employer ceases attempts. For controlled substances, the employer ceases attempts if the test is not administered within 32 hours. The citation triggers have their own windows: a citation received within 8 hours for the alcohol test and within thirty-two hours for the controlled substances test.

The section also says a driver subject to post-accident testing must remain readily available for it, and that nothing in the section is to be read as requiring the delay of necessary medical attention.

An attenuator truck is hit as part of its job. That is the scenario this section is written for. A company that runs shadow trucks should decide in advance who makes the call, where the driver is taken, and who documents the times. See work zone intrusion prevention and response.

Random

49 CFR 382.305 requires every employer to run random testing. It sets the minimum annual percentage rate at 10 percent of the average number of driver positions for alcohol and 50 percent of the average number of driver positions for controlled substances. The FMCSA Administrator can raise or lower those rates based on industry violation data and publishes changes in the Federal Register, so confirm the current rate each year.

A small company cannot run a meaningful random pool on its own. Three drivers do not make a pool. Most small carriers join a consortium, which combines many employers' drivers into one pool, makes the selections and reports them.

What the employer has to do is act on a selection promptly and make sure selected drivers actually go.

Reasonable suspicion

Under 49 CFR 382.307, an employer requires a test when it has reasonable suspicion that a driver has violated the alcohol or controlled substances prohibitions. The section states that the determination "must be based on specific, contemporaneous, articulable observations concerning the appearance, behavior, speech or body odors of the driver."

The observations have to be made by a supervisor or company official who has had the training the rule requires. That training is set by 49 CFR 382.603: at least 60 minutes on alcohol misuse and at least an additional 60 minutes on controlled substances use, covering the physical, behavioral, speech and performance indicators. The section says recurrent training is not required.

For a traffic control company, the supervisor in question is usually a crew lead or dispatcher at 5 a.m. If nobody on the early shift has had the training, the company has no one who can make the determination. See training new traffic control crew leads.

Return-to-duty and follow-up

Sections 382.309 and 382.311 say these tests are performed in accordance with 49 CFR Part 40, Subpart O. Part 40 is the Department of Transportation's procedural rule for how testing is conducted across all the transportation modes. A driver who has violated the rules goes through an evaluation and return-to-duty process described there before performing safety-sensitive functions again.

The alcohol threshold

49 CFR 382.201 states the basic prohibition. No driver shall report for duty or remain on duty requiring the performance of safety-sensitive functions while having an alcohol concentration of 0.04 or greater, and no employer with knowledge of that shall permit it.

The required educational materials also have to explain the consequences for a driver found to have an alcohol concentration of 0.02 or greater but less than 0.04. Read the subpart for the full list of prohibited conduct.

The Clearinghouse

The Drug and Alcohol Clearinghouse is FMCSA's database of CDL drivers' program violations. 49 CFR 382.701 sets the employer's query obligations.

Pre-employment query. An employer must not use a driver to perform a safety-sensitive function without first conducting a pre-employment query. It has to be a full query, which requires the driver's specific consent.

Annual query. An employer must query the Clearinghouse at least once per year for all employees subject to testing. A limited query, which only reports whether information exists, satisfies the annual requirement with the driver's consent.

The 24-hour follow-up. If a limited query shows that information exists, the employer must conduct a full query within 24 hours. If it does not, the driver cannot continue performing safety-sensitive functions until the full query is done and the record shows no prohibition.

Notification. If information is entered about a driver during the 30-day period after an employer's query, FMCSA notifies the employer.

The annual query is the easiest obligation in the program to miss, because nothing prompts it. Put it on a calendar with a named owner.

The written policy

49 CFR 382.601 requires each employer to provide educational materials explaining the requirements and the employer's policies. A copy goes to each driver before testing starts and to each driver subsequently hired or transferred into a position requiring driving a commercial motor vehicle.

The section lists required content. It includes the person designated to answer driver questions, which categories of drivers are subject to the rule, what period of the workday the driver must be in compliance, prohibited conduct, the circumstances for testing, the procedures used, what counts as a refusal, and the consequences of violations.

Note the word "transferred". A flagger promoted to attenuator truck driver is being transferred into a covered position. That person needs the materials, the pre-employment test and the Clearinghouse query before the first shift in the truck.

Records and how long to keep them

49 CFR 382.401 requires records to be maintained in a secure location with controlled access, on this schedule:

Minimum retention	Examples from the section
Five years	Alcohol test results of 0.02 or greater, verified positive controlled substances results, refusals, driver evaluations and referrals, records related to administration of the program, annual summaries
Two years	Records related to the collection process
One year	Negative and canceled controlled substances results, alcohol results below 0.02

"Secure location with controlled access" is a deliberate requirement. Test records are not kept in the general personnel file where a dispatcher can browse them.

How this shows up in dispatch

The rule creates a simple operating constraint. Certain trucks can only be assigned to certain people.

A dispatcher building tomorrow's board at 4 p.m. needs to know, without looking anything up, which crew members hold a CDL, are in the testing program, and have a current Clearinghouse query. When a regular attenuator driver calls in sick, the substitute has to come from that list.

Ways companies handle it:

• Tag the qualification on the person. CDL class, medical card expiry, program enrollment date and last Clearinghouse query date sit on the crew member's record. See tracking crew qualifications before dispatch.
• Tag the requirement on the vehicle. Each truck or combination is marked as CDL-required or not, based on its ratings.
• Keep a bench. One CDL driver per attenuator truck leaves no margin. Cross-qualifying a second person per truck costs a pre-employment test and some training.
• Never improvise in the field. Crew leads need a standing rule that a non-CDL crew member does not move a CDL-required vehicle on a public road.

This also affects what you can bid. A job that needs four shadow trucks needs four qualified drivers per shift, plus cover. See crew utilization metrics and hiring and retaining flaggers.

What agencies and primes may ask for

DOT prequalification packages and prime contractor onboarding forms often ask whether you have a drug and alcohol program and who administers it. Being able to hand over a written policy, a consortium enrollment letter and a named program contact shortens that step. See DOT prequalification for traffic control contractors and safety records and EMR in prequalification.

A setup checklist

1. List every vehicle and trailer with its rating. Mark each truck and each common combination as CDL-required or not under the 49 CFR 383.5 definition, and confirm borderline cases with your state agency.
2. List every person who drives a CDL-required vehicle, including owners and occasional drivers.
3. Enroll in a consortium or third-party administrator for random selection and collection.
4. Write and distribute the policy materials that section 382.601 requires.
5. Register in the Clearinghouse, run full pre-employment queries for new drivers, and calendar the annual query.
6. Train every supervisor who might make a reasonable suspicion determination.
7. Write a one-page post-accident procedure with the two-hour, eight-hour and 32-hour marks on it, and put it in every CDL-required truck.
8. Set up record storage with restricted access and the retention schedule from section 382.401.
9. Add the driver qualification to your dispatch records so the board cannot be built wrong.

Where software fits

Traffic OS does not run a drug and alcohol testing program. A consortium, a collection site, a medical review officer and FMCSA's Clearinghouse do that.

What it handles is the dispatch side: crew scheduling that shows who is assigned to which truck, crew records where qualifications and expiry dates can be kept, and GPS-stamped signed daily tickets that record who was on the job and when. Pricing is flat by tier at $499, $949 or $1,499 per month as of October 2026, with no per-user charge. See pricing and features, or book a demo.

Summary

The federal testing program follows the commercial driver's license. Start with the ratings on your vehicles, identify who drives the ones that require a CDL, and put those people in a program before they drive. Flaggers on foot are outside the federal rule as written, but they can enter it the day they are handed the keys to a heavy truck. Confirm how the rules apply to your fleet with FMCSA, your state agency or a compliance adviser.