49 CFR § 105.20 - Guidance and interpretations.

---
identifier: "/us/cfr/t49/s105.20"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "49 CFR § 105.20 - Guidance and interpretations."
title_number: 49
title_name: "Transportation"
section_number: "105.20"
section_name: "Guidance and interpretations."
chapter_name: "PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION"
subchapter_number: "A"
subchapter_name: "HAZARDOUS MATERIALS AND OIL TRANSPORTATION"
part_number: "105"
part_name: "HAZARDOUS MATERIALS PROGRAM DEFINITIONS AND GENERAL PROCEDURES"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "49 U.S.C. 5101-5128; 49 CFR 1.81 and 1.97."
regulatory_source: "67 FR 42951, June 25, 2002, unless otherwise noted."
cfr_part: "105"
---


# 105.20 Guidance and interpretations.

(a) *Hazardous materials regulations.* You can obtain information and answers to your questions on compliance with the hazardous materials regulations (49 CFR parts 171 through 180) and interpretations of those regulations by contacting PHMSA's Office of Hazardous Materials Safety as follows:

(1) Call the Hazardous Materials Information Center at 1-800-467-4922 (in Washington, DC, call (202) 366-4488). The Center is staffed from 9 a.m. through 5 p.m. Eastern time, Monday through Friday except Federal holidays. After hours, you can leave a recorded message and your call will be returned by the next business day.

(2) E-mail the Hazardous Materials Information Center at *[email protected].*

(3) Obtain hazardous materials safety information via the Internet at *http://www.phmsa.dot.gov.*

(4) Send a letter, with your return address and a daytime telephone number, to: Standards and Rulemaking Division, Pipeline and Hazardous Materials Safety Administration, Attn: PHH-10, U.S. Department of Transportation, East Building, 1200 New Jersey Avenue, SE., Washington, DC 20590-0001.

(b) *Federal hazardous materials transportation law and preemption.* You can obtain information and answers to your questions on Federal hazardous materials transportation law, 49 U.S.C. 5101 *et seq.,* and Federal preemption of State, local, and Indian tribe hazardous material transportation requirements, by contacting PHMSA's Office of the Chief Counsel as follows:

(1) Call the office of the Chief Counsel at (202) 366-4400 from 9 a.m. to 5 p.m. Eastern time, Monday through Friday except Federal holidays.

(2) Access information from the Office of the Chief Counsel via the Internet at *http://www.phmsa.dot.gov.*

(3) Send a letter, with your return address and a daytime telephone number, to: Office of the Chief Counsel, Pipeline and Hazardous Materials Safety Administration, Attn: PHC-10, U.S. Department of Transportation, East Building, 1200 New Jersey Avenue, SE., Washington, DC 20590-0001.

(4) Contact the Office of the Chief Counsel for a copy of applications for preemption determinations, waiver of preemption determinations, and inconsistency rulings received by PHMSA before February 1, 1997.

[70 FR 56087, Sept. 23, 2005, as amended at 72 FR 55682, Oct. 1, 2007; 76 FR 56310, Sept. 13, 2011]