Who this is for: CDL drivers, fleet managers, owner-operators
Hazmat Loading and Segregation Rules for CMV Drivers
Hazardous materials have loading and segregation requirements that prohibit loading certain materials together. Incompatible materials may react dangerously if a container is breached. Federal rules specify which hazard classes cannot be loaded in the same vehicle, and prohibit loading hazmat near passengers or food products under certain conditions.
Important Notice
The segregation table and loading requirements are in 49 CFR 177.834 and 177.848. Requirements vary significantly by hazard class and material. This page provides a general introduction — always consult the full segregation table for your specific materials.
The driver's responsibility at loading
Under 49 CFR 177.834, the driver of a hazmat-carrying vehicle must not permit the loading of incompatible materials. While the shipper is primarily responsible for proper packaging and classification, the driver has an obligation to refuse a load that appears to violate segregation requirements. Drivers should be familiar with the basic incompatibility rules for the types of hazmat they regularly transport.
Segregation requirements — what cannot be loaded together
49 CFR 177.848 provides a segregation table that specifies which hazard classes must be separated. Key incompatibilities include: explosives (Class 1) with certain corrosives, flammable liquids, and other explosives; poisons (Division 6.1 and Division 2.3) generally cannot be loaded with food or other human consumable materials; oxidizers (Class 5) with flammable liquids and solids. The segregation table is organized by hazard class and division — drivers transporting multiple hazard classes should consult the table before loading.
Prohibited loading with passengers and food
Certain hazardous materials may not be transported in a vehicle carrying passengers. Explosives (with limited exceptions), flammable compressed gases, and certain other materials are prohibited from vehicles carrying passengers for hire. Additionally, some hazardous materials — particularly poisons and infectious substances — may not be loaded in the same vehicle with food intended for human or animal consumption, except as specifically permitted under the regulations.
Securing loads during transport
49 CFR 177.834 requires that hazardous materials packages be loaded, blocked, and braced to prevent movement during normal transport conditions. Cylinders (compressed gases) must be secured upright or in approved racks. Packages must not be stacked if stacking would damage the packaging. Liquid containers must be loaded with the closure end up. The driver is responsible for inspecting the load before departure and at each stop where the trailer is opened.
Attendance and supervision during loading and unloading
During the loading and unloading of certain high-hazard materials (particularly Class 1 explosives and bulk Class 3 flammable liquids), the driver or another qualified person must be in attendance — not inside the cab — and must be within reach of a fire extinguisher. Engine shutdown requirements during fuel transfer (flammable liquid loading) apply to prevent ignition. Specific attendance requirements vary by material and operation type.
Checking segregation when picking up additional hazmat en route
The segregation problem gets more complicated on LTL routes where new cargo is added at multiple stops. At each pickup, the driver needs to know what hazmat is already on the trailer and whether the new shipment is compatible. This isn't something to figure out at the dock — it requires knowing your current cargo before accepting additional freight. Carry a copy of the 49 CFR 177.848 segregation table or have it accessible digitally. When in doubt before accepting a pickup, call the carrier or dispatcher rather than guessing. An incompatible combination loaded at a shipper dock creates a liability and safety problem that only gets worse the further the truck travels.
Frequently Asked Questions
What if the shipper has already loaded incompatible materials before the driver arrives?
The driver must not accept the shipment if incompatible materials are loaded in violation of segregation requirements. The driver should notify the shipper and carrier. Accepting a load with known segregation violations exposes the driver and carrier to enforcement action.
Does hazmat segregation apply to LTL (less-than-truckload) shipments?
Yes. Segregation requirements apply regardless of shipment size or freight type. LTL carriers must be especially careful when combining multiple hazmat shipments from different shippers on the same vehicle.
On an LTL route, a newly picked-up hazmat shipment appears incompatible with materials already on the trailer — what should the driver do?
Do not load the new shipment. Contact the dispatcher and the shipper immediately. The driver must refuse any pickup that would create an incompatible combination under the 49 CFR 177.848 segregation table. Accepting the load and driving away creates a violation and a genuine safety risk if either package is breached. The carrier must arrange a separate vehicle or reschedule the pickup.
Who is responsible if incompatible materials are already loaded when the driver arrives — the shipper or the driver?
Both can face liability. Under 49 CFR 177.834, the driver must not permit the transportation of incompatible materials — the duty to refuse a non-compliant load falls on the driver as well as the shipper. Accepting a load the driver knew or should have known was non-compliant exposes both the driver and the carrier to enforcement action. When in doubt, check the 177.848 segregation table before accepting.