Hazmat classes

Hazardous-material drayage is the short-distance movement of a container that contains regulated dangerous goods, usually between a marine terminal or rail ramp and a warehouse, distribution center, yard, or transload facility. The mileage may be short, but the compliance chain crosses shipper, port, ocean or rail carrier, motor carrier, driver, facility, and emergency-response responsibilities.

This guide explains the nine U.S. Department of Transportation hazard classes, the information that belongs with a hazmat load, the ways hazmat changes container drayage, and how to check whether a carrier and driver fit the shipment. It focuses on U.S. road drayage under the federal Hazardous Materials Regulations, or HMR, in 49 CFR Parts 171–180.

Important: This article is a planning guide, not a classification, packaging, legal, or emergency-response determination. The shipper or other person offering the material for transportation remains responsible for proper classification and compliance. Always use the current regulations, the product-specific shipping information, and qualified hazmat personnel.

The essentials

A hazard class tells you the material's main transportation hazard. It does not provide the complete shipping description or automatically determine whether a particular container, route, terminal, driver, or carrier can accept the load.

For drayage planning, keep these points separate:

• Hazard class: One of Classes 1 through 9, sometimes divided further, such as 2.1 or 4.3
• Identification number: A four-digit UN or NA number that identifies a regulated entry, such as UN1090
• Proper shipping name: The regulated name paired with the identification number in the Hazardous Materials Table
• Subsidiary hazard: An additional hazard that may require communication even though another class is primary
• Packing group: When assigned, the degree of danger within a class: PG I is great danger, PG II is medium danger, and PG III is minor danger
• Quantity and packaging: Factors that can change packaging, marking, labeling, placarding, registration, permit, and operating requirements
• Mode and route: Vessel, rail, highway, terminal, state, tunnel, and local restrictions can all affect acceptance

A common basic shipping description follows this sequence:

UN1090, Acetone, 3, PG II

The PHMSA guide to using the HMR explains how the identification number, proper shipping name, class or division, and packing group work together. The legally controlling details appear in the current Hazardous Materials Table in 49 CFR 172.101.

How hazmat classification works

Classification starts with the material, not the trucking rate. The offeror must determine what the product is, which hazards it presents, and which regulated entry and packaging instructions apply before offering it for transportation.

Read the Hazardous Materials Table as a complete row

The Hazardous Materials Table is the backbone of the HMR. Its columns identify or point to:

1. Symbols that signal special conditions
2. The proper shipping name and description
3. The primary hazard class or division
4. The UN or NA identification number
5. The packing group, when assigned
6. Required hazard labels
7. Special provisions
8. Packaging exceptions and non-bulk or bulk packaging requirements
9. Quantity limits for passenger and cargo aircraft
10. Vessel stowage requirements

Do not stop after finding a familiar product name or a four-digit number. Concentration, mixture composition, physical form, temperature, packaging, quantity, and mode can change the correct entry or applicable requirements.

Separate primary class, division, and subsidiary hazards

The primary class represents the predominant transportation hazard. A division is a more specific category within a class. For example, Class 2 includes flammable gas (2.1), non-flammable non-poisonous gas (2.2), and poisonous gas (2.3).

A material can also present one or more subsidiary hazards. Those hazards can affect its full shipping description, labels, placards, segregation, handling, and acceptance. The precedence rules for a material meeting more than one class appear in 49 CFR 173.2a.

Understand packing groups

Packing groups describe the relative degree of danger for materials to which they are assigned:

• Packing Group I: Great danger
• Packing Group II: Medium danger
• Packing Group III: Minor danger

Not every class uses packing groups. Class 2 gases and Class 7 radioactive materials, for example, use other classification and control systems. Never invent a packing group because a quote form appears to expect one; use the current HMT entry and applicable Part 173 criteria.

Treat the SDS as a starting point

Section 14 of a current Safety Data Sheet may list transport information such as the UN number, proper shipping name, class, packing group, and environmental hazards. It is useful for collecting shipment data, but it is not a substitute for a transportation classification review.

OSHA requires the Section 14 heading but does not enforce its content because transport regulation belongs to other agencies, as explained in OSHA's SDS requirements. The offeror's responsibility to classify, describe, package, mark, and label the shipment appears in 49 CFR 173.22.

The nine hazard classes in drayage

The classes below summarize the principal hazard. The precise definition, exceptions, packaging instructions, and special provisions for a real shipment must come from the HMR and its Hazardous Materials Table. PHMSA's 2024 Emergency Response Guidebook is also a valuable initial-response reference, but it is not a substitute for compliance with the regulations.

Class 1: explosives

Class 1 covers explosive substances and articles. It is divided by the behavior of the hazard:

• Division 1.1: Mass explosion hazard
• Division 1.2: Projection hazard without a mass explosion hazard
• Division 1.3: Fire hazard with minor blast, minor projection, or both, but no mass explosion hazard
• Division 1.4: Minor explosion hazard, generally confined to the package
• Division 1.5: Very insensitive substances with a mass explosion hazard
• Division 1.6: Extremely insensitive articles without a mass explosion hazard

Drayage context: Class 1 can trigger the narrowest carrier pool, strict terminal or port approvals, quantity-specific permits, security planning, designated routes, parking and attendance rules, segregation, and advance vessel documentation. Certain explosives require PHMSA classification approval, and certain types or quantities require an FMCSA Hazardous Materials Safety Permit. Do not send a driver to the terminal until the steamship line or rail carrier, terminal, motor carrier, route, and consignee have all accepted the exact division and quantity.

Class 2: gases

Class 2 covers gases under pressure and is divided into:

• Division 2.1: Flammable gas
• Division 2.2: Non-flammable, non-poisonous compressed gas
• Division 2.3: Gas poisonous by inhalation

Common shipping forms include cylinders, tube modules, portable tanks, tank containers, and refrigerated liquefied gases. The same class number can still involve very different pressures, temperatures, toxicities, and equipment.

Drayage context: Confirm container or tank condition, valve protection, pressure-control requirements, securement, ventilation restrictions, temperature management, and receiver readiness. Division 2.3 and other inhalation-hazard shipments can trigger more stringent routing, permit, safety-plan, and carrier requirements. A tank-container move also requires equipment and chassis review; a driver's hazmat endorsement alone does not establish that the carrier can handle the specific tank or commodity.

Class 3: flammable and combustible liquids

Class 3 includes liquids classified by flash point and other HMR criteria. Examples can include fuels, alcohols, solvents, paints, adhesives, and chemical mixtures, but a commercial product name alone does not establish its classification.

Drayage context: Class 3 is common in packaged chemical containers and tank containers. Planning may involve ignition-source control, container integrity, compatible stowage, spill response, terminal limits, and tunnel or local route restrictions. The flash point, packing group, quantity, packaging type, and whether the load is bulk or non-bulk can materially change the requirements.

Class 4: flammable solids and water-reactive materials

Class 4 is divided into:

• Division 4.1: Flammable solids, self-reactive materials, and related entries
• Division 4.2: Spontaneously combustible materials, including certain self-heating or pyrophoric materials
• Division 4.3: Materials that emit flammable gas when in contact with water

Drayage context: Moisture exclusion, temperature control, packaging integrity, fire-fighting limitations, and segregation are critical. A leaking or wet container can transform the operating risk, especially for Division 4.3. Some Class 4 materials require approvals or special handling. Confirm that the destination can receive the cargo and that the emergency instructions match the exact material rather than only the broad class.

Class 5: oxidizers and organic peroxides

Class 5 is divided into:

• Division 5.1: Oxidizing substances that can cause or intensify combustion
• Division 5.2: Organic peroxides, which may be thermally unstable and can burn rapidly or react dangerously

Drayage context: Keep incompatible fuels, oils, reducing agents, and other prohibited materials separated as required. Some organic peroxides have control and emergency temperatures, so a reefer or other temperature-managed setup may be a safety requirement rather than a normal refrigerated-cargo preference. Power continuity, genset planning, terminal dwell, appointment reliability, and contingency procedures can therefore affect whether the move is serviceable.

Class 6: toxic and infectious substances

Class 6 is divided into:

• Division 6.1: Toxic materials
• Division 6.2: Infectious substances

Division 6.1 can include materials toxic by ingestion, skin absorption, or inhalation. Poison-inhalation-hazard status, hazard zone, concentration, and quantity can add significant controls. Division 6.2 covers regulated infectious substances and uses specialized packaging and documentation rules.

Drayage context: Verify the emergency-response contact, exposure controls, package integrity, consignee capability, cleaning or decontamination procedures, and any security or permit requirements. Never describe a load only as “toxic” when the division, identification number, packing group or hazard zone, and subsidiary hazards are available.

Class 7: radioactive material

Class 7 covers radioactive material and uses activity, package category, transport index, criticality safety index, contamination, and radiation-level controls rather than ordinary packing groups.

Drayage context: The exact radionuclide, activity, package type and category, labels, indices, route, permits, carrier program, and receiver authorization matter. Highway-route-controlled quantities have preferred-route rules and can require an FMCSA safety permit. Class 7 should be treated as specialized capacity requiring advance manual confirmation, not as a routine hazmat accessorial.

Class 8: corrosive material

Class 8 covers liquids and solids that destroy skin tissue or corrode steel or aluminum at regulated rates. Examples can include acids, alkalis, battery fluids, and cleaning or industrial chemicals.

Drayage context: Confirm compatible packaging, leak-free container condition, segregation from incompatible materials, spill-response capability, and facility unloading procedures. A corrosive can also have a subsidiary toxic, oxidizing, or flammable hazard. Tank containers require particular attention to lining, valves, prior cargo, cleaning documentation, and receiver connections.

Class 9: miscellaneous hazardous material

Class 9 covers regulated transportation hazards that do not fit Classes 1 through 8. Depending on the entry and mode, examples can include lithium batteries, elevated-temperature materials, environmentally hazardous substances, and other regulated articles or substances.

Drayage context: “Miscellaneous” does not mean low risk or unregulated. Lithium batteries, for example, can present state-of-charge, damage, packaging, marking, and fire-response issues. Marine pollutants can introduce vessel and port requirements. A Class 9 placard is generally not required for domestic U.S. transportation, but other marks, labels, shipping papers, international placards, and mode-specific requirements may still apply. Check the exact HMT entry and movement rather than relying on the class name.

Why hazmat changes a drayage move

Containerization does not remove the underlying hazard. It adds handoffs, gate rules, equipment interchange, terminal dwell, and mode changes that must all preserve the correct hazard communication.

Vessel, rail, and highway rules overlap

A marine import can begin under the International Maritime Dangerous Goods Code and continue under the U.S. HMR. U.S. rules address international standards in Part 171, while mode-specific requirements appear in:

• 49 CFR Part 174 for rail
• 49 CFR Part 176 for vessel
• 49 CFR Part 177 for public highway

The Coast Guard explains its packaged-hazmat role and coordination with PHMSA on its packaged hazardous materials page. For international vessel shipments, check the current IMO IMDG Code edition and the ocean carrier's dangerous-goods procedure.

An ocean carrier's acceptance does not automatically prove that the U.S. road leg is ready. Likewise, a trucker's willingness to quote the road leg does not replace vessel, rail, terminal, or consignee acceptance.

Documentation must stay aligned

Unless an exception applies, the shipping paper must carry the regulated basic description and any required additional information. The shipping-description rule in 49 CFR 172.202 is the starting point.

A dispatch-ready file may need:

• Identification number and proper shipping name
• Primary class or division and subsidiary hazards
• Packing group, when assigned
• Package count, type, and regulated quantity
• Technical name when required for a generic or n.o.s. entry
• Shipper's certification when required
• Emergency-response information and a monitored emergency telephone number
• Dangerous-goods declaration or vessel documentation when applicable
• Special permit, approval, exemption, waste manifest, or competent-authority documents when applicable
• Container number, seal, terminal, booking or release reference, facility, and appointment details

The emergency number must meet 49 CFR 172.604, including monitoring while the material is in transportation and access to a person knowledgeable about the material. A generic office voicemail or an unarranged third-party number is not enough.

Labels, marks, and placards are different

Labels normally communicate hazards on packages. Marks communicate details such as identification numbers, proper shipping names, orientation, limited-quantity status, marine-pollutant status, or lithium-battery handling, depending on the shipment. Placards communicate hazards on bulk packages, freight containers, vehicles, or rail cars when required.

Placarding depends on class, division, quantity, packaging, and exceptions. Some hazards require placards at any regulated quantity, while many Table 2 materials use an aggregate threshold. When a freight container must be placarded, placards are generally displayed on each side and each end. Use the current placarding rule in 49 CFR 172.504 and PHMSA's marking, labeling, and placarding guide.

Do not add, remove, or cover placards based only on a photo, an old booking, or a verbal instruction. Confirm the actual cargo and current rules.

Bulk status follows the packaging, not the container length

A 20GP or 40HC freight container loaded with drums, boxes, or intermediate bulk containers is not automatically one bulk package merely because the outer container is large. An ISO tank or another qualifying large packaging can be a bulk packaging. This distinction affects HMT packaging instructions, identification-number displays, placarding, loading, registration, and carrier requirements.

Confirm the actual inner packaging and capacities. Do not determine bulk status from the container number, equipment size, gross cargo weight, or a photo of the exterior.

Segregation and securement affect the whole container

Incompatible hazardous materials may not be loaded together merely because each package is individually compliant. Highway segregation requirements appear in 49 CFR 177.848, with separate vessel stowage and segregation requirements under Part 176 and the IMDG Code.

Blocking, bracing, weight distribution, package orientation, closure integrity, and container condition matter throughout the move. A sealed ocean container is not permission to ignore visible leakage, damage, incorrect placards, or conflicting paperwork.

Routing and timing can change

Hazmat routes can be designated, preferred, or restricted by class and jurisdiction. Check FMCSA's National Hazardous Materials Route Registry and state or local requirements. Tunnel, bridge, ferry, parking, attendance, weather, and urban restrictions may alter the normal drayage route.

Terminals and ocean carriers can also impose dangerous-goods cutoffs, pre-approval, restricted receiving windows, or commodity exclusions. Late disclosure can cause a rejected gate move, rolled export booking, storage, demurrage, detention, re-delivery, or a truck ordered but not used.

Security plans can be shipment-specific

All hazmat employees need security-awareness training, and persons handling certain materials or quantities must develop and follow a written security plan. The applicability rules in 49 CFR 172.800 and plan requirements in 49 CFR 172.802 address personnel security, unauthorized access, and en-route security.

For drayage, that can affect who receives shipment data, where a loaded container may wait, how stops and route changes are handled, and how custody is transferred. Do not publish sensitive route, seal, or emergency information more broadly than the operating parties need.

Empty packages can remain regulated

An empty tank container, drum, or other packaging that still contains hazardous residue may remain subject to the HMR. The rules for empty packagings appear in 49 CFR 173.29.

For a tank return or repositioning move, confirm the last contained product, residue status, cleaning or gas-free documentation, closures, marks, placards, and shipping paper requirements. The word “empty” on a dispatch order is not enough to treat the equipment as non-hazmat.

Hazmat and overweight are separate checks

A container can be both hazardous and overweight. The class affects hazardous-material handling and carrier eligibility; the cargo weight affects container payload, chassis tier, axle loading, permits, and route support. One surcharge does not cover the other.

Provide net cargo weight for Portmate's weight and pricing calculations, plus the regulated package quantities required for the shipping papers. If the container may be heavy, review container chassis types and check the lane before booking.

What to provide before requesting a hazmat quote

Early pricing can begin with a lane and primary classification, but a safe booking needs the full operational picture. Gather the following before the container reaches a port or rail cutoff.

Minimum pricing inputs

• Import or export move
• Exact marine terminal or rail ramp, if known
• Pickup or delivery facility ZIP code
• Container type, such as 20GP, 40HC, or an applicable reefer type
• Commodity description
• Net cargo weight
• Clear statement that the cargo is hazmat
• UN or NA identification number, or the confirmed primary class if the number is not available

Dispatch-ready hazmat inputs

• Complete basic shipping description
• Division and subsidiary hazards
• Packing group, when assigned
• Package types, counts, and quantities
• Bulk or non-bulk status
• Marine-pollutant, poison-inhalation-hazard, temperature-control, or other special status
• Current SDS and any required approval or special-permit documents
• Emergency-response information and monitored telephone number
• Ocean or rail dangerous-goods acceptance and reference
• Required placards and marks already confirmed by qualified personnel
• Pickup date, last free day or cutoff, appointment, and receiver hours
• Any tank, reefer, genset, chassis, overweight, escort, or special equipment need

Do not write only “chemical,” “battery,” “paint,” or “hazmat.” Those descriptions do not tell pricing or operations which class, carrier qualifications, route, equipment, or terminal rules apply.

How to evaluate the carrier and driver

“Hazmat authorized” is not one universal credential. The correct carrier and driver depend on the material, quantity, packaging, mode, route, and facility.

Use this checklist before tendering the load:

• Motor-carrier registration and authority: Confirm the carrier's USDOT record and applicable operating authority. The FMCSA SAFER Company Snapshot provides public identification and safety information.
• PHMSA registration: Confirm current annual hazmat registration when the shipment falls within the thresholds in 49 CFR Part 107, Subpart G. PHMSA provides an online registration service.
• Hazardous Materials Safety Permit: Determine whether the exact material and quantity require an HMSP. This permit applies only to specified high-risk materials and quantities, not to every hazmat load. Review the FMCSA HMSP program.
• Driver endorsement: A driver operating a vehicle that requires placards generally needs a CDL with an H endorsement; a qualifying tank vehicle carrying hazmat generally needs an X endorsement. FMCSA explains the hazmat endorsement requirement.
• Training: Hazmat employees must receive general-awareness, function-specific, safety, security-awareness, and any required in-depth security training. Employers must test, certify, and retain records. Review the PHMSA training requirements.
• Insurance: Confirm that the carrier maintains the insurance appropriate to its authority, commodity, vehicle, and quantity. Do not infer adequate hazmat coverage from a certificate that does not match the operating entity or shipment.
• Route and permits: Check federal, state, local, tunnel, and commodity-specific routing or permit requirements for the planned road leg.
• Port and equipment access: A driver may need a valid TWIC for unescorted access to secure maritime areas. TSA explains the Transportation Worker Identification Credential. Terminal registration, interchange participation, chassis access, appointments, and facility-specific badges are separate operational checks.
• Commodity and equipment experience: Confirm that the carrier accepts the exact class or division, packaging, quantity, tank or container type, temperature requirement, and emergency procedure—not merely “hazmat” in general.

The carrier may rely on accurate shipper-provided information unless it knows or reasonably should know that the information is wrong. That is why the classification and documents must be complete before carrier assignment.

What Portmate automates

Portmate reduces the pricing and coordination work around a disclosed hazmat drayage move. You can provide the lane, container, commodity, weight, and classification once in chat instead of calling multiple carriers and rebuilding the shipment details in separate emails.

Classification-aware quote intake

When you say that the cargo is hazardous, Portmate captures the hazmat status with the quote. You can provide an identification number such as UN1090, a primary class from 1 through 9, or both.

For recognized UN or NA numbers, Portmate normalizes the identifier and can resolve the associated primary class for pricing. If the number is unknown, incomplete, ambiguous, or conflicts with the class supplied, Portmate asks for clarification rather than silently pricing a contradictory classification.

This lookup is a pricing and data-quality safeguard. It does not replace the shipper's duty to provide the proper shipping name, division, subsidiary hazards, packing group, quantity, packaging, marks, labels, placards, emergency information, and certifications.

Instant hazmat pricing without the back-and-forth

Once you provide the hazmat and route details, Portmate evaluates the factors that shape the applicable hazmat charge, including:

• Hazmat pricing for the selected terminal market
• The shipment's primary hazard class
• The lane distance and routing context

Portmate brings those factors into the drayage quote instantly, so you do not need to calculate the charge yourself or call carriers individually to compare handling fees.

The hazmat amount can appear as a separate quote line for visibility. Portmate also evaluates the rest of the move—terminal, facility, container type, cargo weight, chassis needs, and other supported accessorials—so hazmat handling is not confused with overweight, reefer, storage, waiting, or special-equipment charges.

You can review terminal-specific charges in the Portmate accessorial guide.

From rate to carrier coordination

After you accept the quote, Portmate keeps the structured shipment details in the booking flow and manages carrier assignment, shipment confirmation, tracking, and exceptions in one place. Early hazmat disclosure allows the operations team to evaluate carrier, driver, equipment, route, terminal, and commodity fit before dispatch.

Carrier acceptance remains shipment-specific, particularly for explosives, poison-inhalation hazards, radioactive material, temperature-controlled organic peroxides, tank containers, damaged batteries, hazardous waste, and other specialized cargo. Portmate coordinates the workflow; it does not turn incomplete shipper data into a compliant shipment or guarantee that every class is available on every lane.

Example requests

“Quote one 40HC from Savannah Garden City Terminal to ZIP 30304. Net cargo weight is 18,000 kg. Hazmat UN1090, Class 3.”

“Quote a 20GP import from Houston to Pasadena, Texas. The cargo is hazardous, primary Class 8. I will provide the complete shipping description and documents before booking.”

“I need a Class 5.2 export dray. The product is temperature controlled. Check pricing and tell me what operational details are still needed before carrier assignment.”

For the full workflow, follow the instant drayage quote guide, then move the accepted rate into the instant booking flow.

If something is wrong at pickup

Stop the dispatch escalation and involve qualified hazmat personnel if:

• The shipping paper, SDS, booking, labels, marks, or placards disagree
• The container or a package is leaking, bulging, smoking, hot, wet, damaged, or emitting an odor
• Placards are missing, damaged, or appear unrelated to the documents
• The seal or container number does not match the release
• The required emergency number is unavailable
• The driver, carrier, terminal, or receiver has not accepted the exact material
• The planned route conflicts with a restriction or permit

Do not ask an untrained driver to open a sealed container, investigate a vapor, remove a placard, clean a spill, or continue moving an unsafe load.

For a transportation incident that meets reporting criteria, PHMSA explains the immediate and written requirements on its hazmat incident-reporting page. The person in physical possession of the material has specific reporting duties under 49 CFR 171.15 and 171.16; emergency safety and required notifications take priority over routine dispatch communication.

Official resources

Use current primary sources when classifying or tendering a real load:

• eCFR Title 49, Chapter I — federal hazardous-material regulations
• PHMSA guide to using the HMR — practical guide to the table and regulations
• PHMSA markings, labels, and placards guide — visual hazard-communication reference
• PHMSA Emergency Response Guidebook — initial incident-response guidance
• PHMSA hazmat training requirements — employer and employee training overview
• FMCSA guide to federal hazmat compliance — highway carrier, registration, documentation, and placarding overview
• FMCSA Hazardous Materials Safety Permit program — permit scope for specified high-risk loads
• FMCSA National Hazardous Materials Route Registry — designated and restricted highway routes
• U.S. Coast Guard packaged hazardous materials — U.S. vessel and container regulatory context
• IMO IMDG Code — current international maritime dangerous-goods code information

Plan once, then keep the data consistent

The safest and fastest hazmat dray is the one classified before pricing, accepted before dispatch, and documented consistently across every handoff. Give Portmate the lane and hazmat details once, review the class- and distance-aware charge, and carry the same verified shipment data into booking and carrier coordination.

That removes much of the repetitive rate chasing without hiding the compliance work that still matters: correct shipper classification, complete documents, terminal acceptance, compatible equipment, a suitable carrier and driver, and a legal route.