The UN Model Regulations cover all aspects of transportation necessary to provide international uniformity. They include a comprehensive criteria based classification system for substances that pose a significant hazard in transportation. Hazards addressed include explosiveness, flammability, toxicity (oral, dermal and inhalation), corrosivity to human tissue and metal, reactivity (e.g., oxidizing materials, self reactive materials, pyrophoric substances, substances that react with water), radioactivity, infectious substance hazards and environmental hazards. They prescribe standards for packagings and multimodal tanks used to transport hazardous materials. They also include a system of communicating the hazards of substances in transport through hazard communication requirements which cover labeling and marking of packages, placarding of tanks, freight containers and vehicles, and documentation and emergency response information that is required to accompany each shipment.

Based on a proposal from the United States the UN Model Regulations were reformatted in the form of a “Model Regulation”. Many national, regional and modal regulations governing the transport of dangerous goods are now based on the UN Recommendations, some of the regulations were structured differently requiring consignors of dangerous goods to be familiar with the unique structure of all applicable regulations. The lack of structural harmony of regulations can frustrate compliance and to the extent that it results in noncompliance is detrimental to safety. Furthermore, a Model Regulation can easily be adopted in National legislations of countries throughout the world eliminating the need for countries to reissue the regulations in the format of their national regulations.

In the past, the process of incorporating amendments to the UN Recommendations was resource intensive. In the case of international organizations, each change to the Recommendations was reevaluated before being introduced into the various international regulations. In some cases the amendments had to be reproposed by governments participating in these meetings. The fact that each of these issues was rediscussed, reworded and reorganized by each of the affected regulatory bodies increased the likelihood for disharmony. The Model Regulation is serving to reduce the necessity for the majority of these efforts and in turn is enhancing harmonization.

The Transport of Dangerous Goods Sub-Committee (TDG Sub-Committee) provides leadership in internationally harmonizing regulations on the transportation of hazardous materials (dangerous goods) by developing an internationally agreed regulatory framework set out in the United Nations Recommendations on the Transport of Dangerous Goods (UN Model Regulations). The UN Recommendations form the basis for international modal regulations on the transport of dangerous goods prepared by the International Maritime Organization (IMO) and the International Civil Aviation Organization (ICAO). The UN Model Regulations are also used as a basis for the development of regional (e.g., NAFTA and European Road and Rail regulations) and national transport regulations, including the U.S. Hazardous Materials Regulations.

Participants in the TDG Sub-Committee include 27 countries with voting status and numerous countries and non-governmental organizations with observer status. The TDG Sub-Committee is responsible for reviewing proposals from voting member countries and observers in relation to amendments to the UN Recommendations and issues relevant to its work program. The TDG Sub-Committee meets four times in a two year period (biennium). PHMSA represents the United States at these meetings and formulates U.S. positions based on feedback from U.S. industry, the public and other government agencies.

The work of the Committee has become increasingly important to both international and domestic transportation of hazardous materials to, from and within the United States. Virtually all hazardous materials imported to or exported from the United States are transported in accordance with international regulations based on the UN Recommendations. In the case of the U.S., the decisions of the TDG Sub-Committee affect an international trade volume in hazardous materials with an estimated dollar value of $160 (based on 2003 data) billion annually. Domestically the US Chemical industry accounted for shipments of chemicals valued at approximately $466.4 billion in 2003. In addition to enhancing safe transportation through improved regulatory consistency, international harmonization of hazardous materials regulations plays a significant role in maintaining a U.S. favorable balance of trade in chemicals. The work of the TDG Sub-Committee also affects a much larger domestic hazardous materials transportation volume.

PHMSA is interested in comments on proposals submitted to the TDG Sub-Committee and will consider comments in formulating formal U.S. positions on UN proposals. Comments should be sent in writing to Bob Richard at bob.richard@dot.gov or Duane Pfund at duane.pfund@dot.gov. Copies of TDG Sub-Committee documents may be downloaded from the UN Transport Secretariat's website.

The following countries have expert status and as such are able to vote on proposals under consideration by the Subcommittee of Experts on the Transport of Dangerous Goods (TDG Subcommittee): Argentina, Australia, Austria, Belgium, Brazil, Canada, China, Czech Republic, Finland, France, Germany, India, Islamic Republic of Iran, Italy, Japan, Mexico, Morocco, Netherlands, Norway, Poland, Portugal, Russian Federation, South Africa, Spain, Sweden, the United Kingdom of Great Britain and Northern Ireland and the United States of America

Refer to the link at the right for a list of TDG Sub-Committee participants.

The United Nations Transport of Dangerous Goods Sub-Committee (TDG Sub-Committee) will meet four times during the 2007-2008 biennium and plans to address a number of issues. PHMSA encourages the public to participate in the work of the TDG Sub-Committee and to comment on the work items. Comments may be provided to Mr. Duane Pfund at (202) 366-0656 or by email at duane.pfund@dot.gov.

The primary topics which the TDG Sub-Committee plans to address during the 2007-2008 biennium include:

• Performance of packagings, including IBCs – The topic of packaging of hazardous materials is one that generally remains on the TDG Sub-Committee's agenda. While the packaging requirements are fairly mature the Sub-Committee consistently strives to introduce incremental improvements to enhance the safety by ensuring the integrity of packagings.
• Limited quantities (multimodal harmonization) – The TDG Sub-Committee is expected to consider requirements for consumer commodities with the goal of harmonizing these requirements in the 2007-2008 biennium.
• Electronic Data Interchange for documentation purposes – The Sub-Committee is considering amending language in the UN Model Regulations to allow electronic communication of hazards to supplement paper documents.
• Harmonization with IAEA Regulations for the Safe Transport of Radioactive Material - The Sub-Committee agreed to consider further harmonization of terminology used for dangerous goods and radioactive material requirements.
• Issues relating the Globally Harmonized System of Classfication and Labelling of Chemicals (GHS) – Listing and classification is a topic that is always on the TDG Sub-Committee's agenda. New data relevant to the classification of certain chemicals is periodically submitted to the Sub-Committee for consideration. It is also anticipated that the minor amendments to classification criteria that will result through the adoption of the GHS will also lead to the reclassification of some hazardous materials (e.g. those with an oral toxicity greater than 300 mg/kg).
• Miscellaneous amendments to the Model Regulations, as necessary

Summary documents discuss the papers submitted to the UN Committee of Experts (COE) and Sub-Committee of Experts (SCOE) on the Transport of Dangerous Goods during recent sessions. The documents highlight the proposals made in the papers and indicate whether or not the proposals were adopted.  Click the link to the right.