# Industrial Consulting Services — Hazardous Materials Safety Interpretation

**Citation:** 99-0025  
**Type / status:** guidance / guidance  
**Agency:** Pipeline and Hazardous Materials Safety Administration  
**Effective:** Not stated  
**Published:** 1999-04-14

99-0025 response to Industrial Consulting Services concerning 172.516.

## Document text

<<<PAGE 1>>>

of Transportation
U.S.Department
Nashington, D.C. 2059
00 Seventh Street, S.W
Research and
pecial Program
dministratio
APR 1 4 1999
Mr. Randy L. Holloway
Industrial Consulting Services
Ref. No. 99-0025
P.O. Box 990
Middleton, ID 83644
Dear Mr. Holloway:
This is in response to your letter dated January 10, 1999, regarding the requirements for visibility and
display of placards on a transport vehicle as prescribed in the Hazardous Materials Regulations (HMR;
49 CFR Parts 171-180).
You asked what is the meaning of the phrase "substantially reduced" as used in 49 CFR 172.516(c)(6),
regarding visibility of placards, and whether it would be a violation of the HMR to use duct tape located
approximately 1/4 inch over the black inner border of the placard, although the symbol, identification
number and hazard class are visible. You also asked whether a small amount of "road spray" may be
on the placard and not be in violation of the HMR.
Section 172.516 requires that a placard must be displayed in a location clear of appurtenances and
devices such as ladders, be located in a position so that dirt or water is not directed to it from the
wheels of the transport vehicle and be visible from the direction it faces. In addition, the requirements
specify that the visibility of the placard will not be "substantially reduced" due to damage, deterioration,
or obscurement by dirt or other matter.
Although, you did not provide any photographs or drawings of the placards, based on the information
you provided, it is the opinion of this Office that the duct tape (used to affix the placard to the motor
vehicle) which covered the black solid line inner border is a violation of the requirements in 49 CFR
172.516(c)(6). In addition, if the placard is located on the motor vehicle where it is liable to be
covered with dirt, snow, mud or other matter (e.g., "road spray"), it is a violation of HMR.
1725|6
990025

<<<PAGE 2>>>

The phrase "substantially reduced" is not defined in the HMR; however, its intent is to prohibit a
placard on a motor vehicle whose format and legibility is diminished, such as by placing duct tape over
the black solid line inner border (a required part of the placard design), or a placard that is damaged,
deteriorated, or obscured, such as by "road spray".
I hope this satisfies you inquiry.
Sincerely,
Dentillio
Delmer F. Billings
Chief, Standards Development
Office of Hazardous Materials Standards

## Provenance

- Official: Yes
- Source: <https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/1999/990025.pdf>
- Source ID: `phmsa`
- SHA-256: `08f35349b4eeaa58c236604634e909bb5ca76740d5f31f587c05cbfde9132562`
- Retrieved: 2026-08-20T00:59:31.977Z
- Exported: 2026-08-22T13:52:13.927Z
- Document slug: `phmsa-interpretation-99-0025`

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