HazMat Transportation

PHMSA, FMCSA, and Placarding: Transporting Hazmat Can Be Confusing

If you ship or transport hazardous materials (hazmat) in commerce, you have obligations under both the Pipeline and Hazardous Materials Safety Administration (PHMSA) and the Federal Motor Carrier Safety Administration (FMCSA). But these two arms of the U.S. Department of Transportation (DOT) have different requirements for the transportation of hazmat. It can be confusing.


PHMSA hazardous materials regulations (HMRs) govern motor carriers, aircraft, railways, and vessels. This discussion is about highway transportation by motor carriers.

Under the PHMSA HMRs, hazardous materials are substances or materials that the DOT has determined are capable of posing an unreasonable risk to health, safety, and property when transported in commerce. Hazardous materials under PHMSA include hazardous substances, hazardous wastes, marine pollutants, elevated temperature materials, materials designated as hazardous in the Hazardous Materials Table found at 49 CFR 172.101, and materials that meet the defining criteria for hazard classes and divisions in 49 CFR 173.


Under FMCSA regulations for commercial driver’s licenses (CDLs), hazardous materials are materials that have been designated as hazardous by the DOT and are required to be placarded under PHMSA HMRs at 49 CFR 172.500 to 172.560, or any quantity of a material listed as a select agent or toxin under the Department of Health and Human Services regulations found at 42 CFR 73.

What’s the Difference?

Although you must comply with both PHMSA and FMCSA requirements, the primary difference between the two sets of regulations has to do with placarding.

PHMSA highway transportation regulations apply only to motor carriers transporting hazmat in commerce. Some of these hazardous materials must be placarded, and some are excepted from placarding.

FMCSA regulations focus on accidents involving large trucks and buses, including those that transport hazmat.

Drivers with CDLs who transport hazmat must have a hazardous materials endorsement (HME). However, an HME is required only for those drivers with CDLs who are transporting hazmat that must be placarded. Drivers should apply for an HME if they have a state-issued CDL and are required to transport materials that require placarding under PHMSA HMRs.

Which Hazmat Must Be Placarded?

Placarding requirements do not apply to:

  • Small quantities of certain hazard classes packaged in accordance with the small, excepted, or de minimis exceptions found at, respectively, 49 CFR 173.4, 49 CFR 173.4a, and 49 CFR 173.4b;
  • Limited quantities (in combination packagings of 66 pounds (lb) or less that display the limited quantity mark);
  • Materials of trade exception at 49 CFR 173.6;
  • Infectious substances;
  • Other regulated material (ORM-D) (e.g., consumer commodities);
  • Combustible liquids in nonbulk packagings; and
  • Hazmat hermetically sealed in packaging prepared in accordance with 49 CFR 173.13 (applies to specified hazard classes that are not toxic inhalation hazards, i.e., classes 3, 8, and 9 and Divisions 4.1, 4.2, 4.3, 5.1, and 6.1).

In addition, the general placarding requirements found at 49 CFR 172.504 provide several placarding exceptions based on the weight of a shipment of materials listed in Table 2 (hazard classes/divisions 1.4, 1.5, 1.6, 2.1, 2.2, 3, combustible liquid, 4.1, 4.2, 5.1, 5.2 (with several exceptions), 6.1 (other than material poisonous by inhalation), 8, and 9). This regulation also provides a placarding exception for class 9 (miscellaneous hazmat) transported within the United States.


Aside from your drivers being required to have an HME for transporting placarded shipments, placarding issues are always prominent in the top 10 hazmat violations list. Three of the top 10 violations so far in fiscal year 2017 have to do with placarding requirements. In some cases the placards were not provided to the carrier, or the vehicle was not properly placarded, or the placards were damaged or obscured.

It’s possible that one of the reasons placarding violations figure so prominently in the DOT roadside inspection statistics is that they are easy to spot. Your placard is either displayed correctly or it is not. And, if you are stopped for a placarding violation, you can be sure that the DOT inspector will have a look at compliance with other requirements. So, it’s a good idea to avoid placarding a hazmat shipment if you can.