Explosives other than small-arms ammunition, along with labeled radioactive materials, may never be placed in the part of a bus where people ride. Proper labels do not change that ban.
Solid Class 6 poisons may ride on a bus only in limited quantity, because carrying more than 100 pounds of them is forbidden. Labeling them does not remove that cap.
A bus may carry a permitted hazardous material only when each package is correctly marked. The markings must name the material, give its ID number, and include the diamond-shaped hazard label.
Tear gas and other irritants, liquid Class 6 poisons, and Division 2.3 poison gas are banned from buses outright. Small-arms ammunition, emergency hospital supplies, and a rider's prescribed personal oxygen are all permitted.
Tear gas belongs to the group of irritating materials that may never ride on a bus carrying passengers. Small-arms ammunition and emergency shipments of hospital supplies or drugs are permitted, up to the weight limits.
Passengers may not bring common hazards such as gasoline or car batteries onto a bus. Oxygen prescribed by a doctor is an exception when it is carried in a container intended for personal use.
Drugs, emergency hospital supplies, and small-arms ammunition marked ORM-D are permitted on a bus, as are limited amounts of some other hazardous materials that cannot be shipped by any other means. Division 2.3 poison gas, liquid Class 6 poisons, and tear gas are never allowed, and labeled radioactive materials may not be carried in the passenger area.
These hazardous materials may ride on a bus only if all of them together weigh 500 pounds or less; a heavier total is not permitted on a passenger vehicle.
Riders may not bring common hazards such as car batteries, gasoline or kerosene onto a bus, because these items can leak, catch fire or explode in the passenger area.
Oxygen prescribed by a doctor is permitted when it travels in a container designed for personal use, and a bus may also carry drugs and emergency hospital supplies. Both items are on the permitted list.
A bus may carry ORM-D small-arms ammunition, drugs, and emergency hospital supplies, plus small amounts of a few other hazardous materials that cannot be shipped any other way. Most hazardous materials are banned, and riders must not carry on common hazards such as car batteries.
No one class of allowed hazardous materials may exceed 100 pounds on a bus. The 500-pound figure is the cap for all allowed hazardous materials combined, not the limit for a single class.
Tear gas and other irritating chemical agents are on the list of materials a bus may never carry. Small-arms ammunition and emergency hospital supplies, by contrast, are allowed in limited amounts.
Taken together, all the allowed hazardous materials on a bus may weigh no more than 500 pounds. In addition, no single hazard class may go over 100 pounds.
ORM-D is the abbreviation for Other Regulated Materials - Domestic, a category of lower-hazard goods, such as many consumer products, that are approved for transport inside the United States only. Since 2021 the ORM-D marking is no longer used for highway shipments and has been replaced by the Limited Quantity mark, but many CDL manuals still mention it.
Small-arms ammunition is the one kind of explosive allowed where people ride, within the 100-pound limit for a single hazard class. Labeled radioactive materials must stay out of that space, and liquid Class 6 poisons may never be carried on a bus at all.
Every question in this set has its own page with the correct answer and an explanation.
