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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Interpretation Response #08-0049 ([Los Alamos National Laboratory] [Ms. Lorelei Johnson])

Below is the interpretation response detail and a list of regulations sections applicable to this response.

Interpretation Response Details

Response Publish Date:

Company Name: Los Alamos National Laboratory

Individual Name: Ms. Lorelei Johnson

Location State: NM Country: US

View the Interpretation Document

Response text:

March 18, 2008


Ms. Lorelei Johnson

Transportation Specialist

Weapons Engineering Technology (WT-DO)

High Explosives Engineering (WT-5)

Los Alamos National Laboratory

P.O. Box 1663, Mail Stop C932

Los Alamos, NM 87545

Reference No. 08-0049

Dear Ms. Johnson:

This is in response to your January 22, 2008 letter asking if a Class 1 (explosive) compatibility group letter must be displayed on an EXPLOSIVE placard when the material is transported by motor vehicle under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). You note that § 172.522(b) requires the compatibility group letter for the Division 1.1, 1.2, or 1.3 (explosives) placard, but § 172.504(g) does not address transportation by motor vehicle.

The answer is no. Section 172.504(g) requires the display of the compatibility group letter on placards or labels, if appropriate (see § 172.411), for shipments of Class 1 material transported by aircraft or vessel only. If more than one compatibility group placard is required, § 172.504(g) requires only one of these placards to be displayed provided this placard conforms with the precedence requirements prescribed in paragraphs (g)(1) through (g)(4) of that section. Although the HMR does not require the compatibility group letter for motor vehicle and railcar shipments of Class 1 material, please note that § 172.502(c) permits it to be displayed provided the placards otherwise conform to the requirements prescribed in 49 CFR Part 172, Subpart F (placarding). Section 172.401(a)(2) also permits a hazard warning label to be displayed provided the label represents the hazard class of the material in the package.

I hope this satisfies your request.


Hattie L. Mitchell

Chief, Regulatory Review and Reinvention

Office of Hazardous Materials Standards

172.504 172.411 172.522

Regulation Sections

Section Subject
172.504 General placarding requirements
172.522 EXPLOSIVES 1.1, EXPLOSIVES 1.2 and EXPLOSIVES 1.3 placards