Location of Subsidiary Hazard Placard
Pipeline and Hazardous Materials Safety Administration · Apr 27, 2007 · Reference No. 07-0071
Interprets: 49 CFR § 172.505
Reggie’s quick take
Someone asked where a subsidiary hazard placard must go in relation to the primary hazard placard on a transport vehicle. PHMSA says the rules do not say whether it goes above, below, left, or right of the primary placard. Subsidiary placards, when § 172.505 requires them, must go on each side and each end of the vehicle, freight container, portable tank, unit load device, or rail car. The visibility and display rules in § 172.516 apply to both primary and subsidiary placards.
Written by AI (Claude) on Oct 22, 2026. Robots make mistakes and leave things out, so the letter below is what counts. Not legal advice.
This is in response to your March 29, 2007 letter regarding placarding requirements under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Specifically, you ask where on a transport vehicle a subsidiary hazard placard must be placed in relation to the primary hazard class placard with which it is associated.
The HMR do not specify where the subsidiary hazard class placard must be placed in relation to the primary hazard class placard (i.e., above, below, to the left or right). Subsidiary hazard placards, when required under § 172.505, must be placed on each side and each end of the transport vehicle, freight container, portable tank, unit load device, or rail car. In addition, the requirements for visibility and display of placards in § 172.516 apply to placards representing both primary hazards and subsidiary hazards.
A letter of interpretation applies the regulations to the facts the requester described. It isn’t a regulation and isn’t legal advice. The agency’s copy.