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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 #17-0141

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

Interpretation Response Details

Response Publish Date:

Company Name: Council on Safe Transportation of Hazardous Articles

Individual Name: Tom Ferguson

Location State: NY Country: US

View the Interpretation Document

Response text:

Tom Ferguson
Sr. Technical Consultant
Council on Safe Transportation of Hazardous Articles
10 Hunter Brock Lane
Queensbury, NY  12804

Reference No. 17-0141

Dear Mr. Ferguson:

This letter is in response to your December 21, 2017, letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to label specifications.  Specifically, you are concerned about recent amendments that mandated a specific inner border line width of at least 2 mm as adopted in the final rule titled “Hazardous Materials: Harmonization With International Standards (RRR)” and published in the Federal Register on January 8, 2015, under Docket No. PHMSA-2013-0260 (HM-215M). 

The HM-215M final rule revised § 172.407(c)(1) to require that: (1) each diamond (square-on-point) label prescribed in the HMR must be at least 100 mm (3.9 inches) on each side with each side having a solid line inner border 5 mm inside and parallel to the edge; (2) the 5‑mm measurement is from the outside edge of the label to the outside of the solid line forming the inner border; and (3) the width of the solid line forming the inner border must be at least 2 mm.

The HM-215M final rule provided transition periods for the adopted amendments, prescribing in § 172.407(c)(1)(iii) that for domestic transportation, a label in conformance with the requirements of § 172.407(c)(1), revised as of October 1, 2014, is authorized for use until December 31, 2016.  The effective date was subsequently revised to December 31, 2018, in a final rule published in the Federal Register on March 30, 2017, under Docket No. PHMSA-2015-0273 (HM-215N). 

The amendments described above were part of a broader effort to improve consistency across label specifications and reduce transportation impediments worldwide.  However, upon implementation of the amendments, rather than improving consistency, it became apparent that the specification of a 2-mm line width posed unintended consequences, such as those you highlight in your correspondence.  As such, PHMSA worked collaboratively at the 51st Session of the United Nations Sub-Committee of Experts on the Transport of Dangerous Goods in July 2017 to address this issue, where it was agreed upon that specifying a minimum thickness for line width was not necessary for safety reasons and an amendment was adopted as proposed.  The Sub-Committee further stated that organizations responsible for modal regulations were invited to amend their respective transportation standards accordingly.  Consequently, the International Civil Aviation Organization (ICAO) and the International Maritime Organization (IMO) have both rescinded the size requirements adopted in the 2015 United Nations Model Regulations effective January 1, 2019 and January 1, 2020, respectively.  These amendments will be considered for implementation by PHMSA as expediently as possible in an upcoming rulemaking action.

I hope this information is helpful.  Please contact us if we can be of further assistance.


T. Glenn Foster
Chief, Regulatory Review and Reinvention Branch
Standards and Rulemaking Division

Regulation Sections

Section Subject
172.407 Label specifications