Shut the engine off first, then examine the cargo area: cargo heaters must be disabled, and you should look for broken floor boards, damaged side panels, and sharp points such as nails, bolts, or screws that could damage the packages.
Some radioactive packages show a transport index on their labels, a number based on how much radiation can be detected 1 meter away. It tells carriers how much control and spacing the shipment needs; corrosives and flammable gases carry no such number.
A heater in the cargo area can ignite Class 1 explosives, Division 2.1 flammable gases, and Class 3 flammable liquids. For that reason the regulations usually forbid heaters in the compartment holding such loads, even automatic units that provide both heating and air conditioning. Don't load them in that kind of space unless you are aware of all the related rules.
A lit cigarette, cigar, or pipe could ignite these cargoes, so smoking is forbidden for everyone within 25 feet of a vehicle hauling explosives, oxidizers, or flammables. The rule targets cargo that can catch fire or explode, which is why poisons and corrosives are not named in it.
Packages of radioactive material with a Yellow-II or Yellow-III label show a transport index, a number that reflects how much radiation control the package needs. The combined transport index of all such packages on one vehicle may not exceed 50.
If containers of nitric acid sit above other cargo, any leak drips down onto it, and this strongly oxidizing acid can react violently or even ignite what it touches. Mixed loads are therefore allowed only when the nitric acid is not stacked on top.
A cargo heater, including a combined heater and air-conditioner unit, could ignite explosives, flammable gases or flammable liquids, which is why Classes 1, 2.1 and 3 are kept out of such trailers.
Metal tools can strike a spark or pierce a package, and either one could set off the explosive contents. Packages of explosives must also never be dropped or thrown, and damp or stained ones should not be accepted at all.
Nitric acid is extremely corrosive and can feed a fire, so it is never placed above any other product. If its container leaked from a higher position, the acid would run down onto the freight below.
The attendant has to stay alert, keep a clear view of the tank, and remain within 25 feet of it for the entire transfer, so that a leak or other emergency can be handled at once.
When the transport index of every radioactive package on board is added up, the total must be 50 or less. This cap keeps the combined radiation from all the packages within safe limits.
One spark from a cigarette, cigar, or pipe could ignite these cargoes, so the 25-foot no-smoking zone around such a vehicle is in force at every moment, whether it is moving, parked, or being loaded.
Every opening on a loaded cargo tank has to be sealed and checked for leaks before departure; otherwise product can escape as soon as the vehicle starts to move.
Packages labeled RADIOACTIVE II or III show a transport index that tells how much control they need in transit, and the indexes of all packages in one vehicle may total no more than 50.
The CDL manual says corrosive liquids must not be loaded next to or on top of Division 1.4 explosives, Division 4.1 flammable solids, or Division 5.1 oxidizers, because a leak from the corrosive could start a dangerous reaction with them.
Without racks, cylinders have to be held upright or laid flat and braced so they cannot roll, slide or tip over and rupture when the vehicle stops or turns. The cargo floor must also be flat.
Federal loading rules forbid carrying Division 1.1 or 1.2 explosives in any combination that also includes a placarded cargo tank, because trouble with either load could quickly involve the other. Doubles and a full trailer with a 200-inch wheelbase are not on the prohibited list, though triples are.
Explosives (Class 1), flammable gases (2.1), flammable liquids (3), and flammable solids (4) can be ignited by a single spark, and oxidizers (5) make any fire burn much hotter, so no one should smoke while these are being loaded or unloaded.
Poisons can leak or leave residue that contaminates food or animal feed before anyone notices, so they must not share a load with anything meant to be eaten by people or animals.
Iron and steel can strike sparks, so the floor lining under Division 1.1 or 1.2 cargo has to be either a nonmetallic material or a metal with no iron in it. Carbon steel and cast iron are both iron-based, so neither qualifies.
The engine may run only while it is driving the transfer pump. As soon as the product has been moved, turn the engine off, and only then disconnect the loading or unloading hoses.
Cyanides must never be loaded with acids, because a mixture of the two could give off deadly hydrogen cyanide gas, so the acid stays off your vehicle and someone, such as your dispatcher, should be told.
A leaking package or shipment must never be accepted for transport; turning it down keeps the hazard off the road, while patching it yourself or hauling it as is puts you and others at risk.
Class 1 explosives, Division 2.1 flammable gases, and Class 3 flammable liquids fall under special cargo heater rules that generally forbid heaters in the cargo space, including combined heater and air conditioner units. Heat can cause these materials to ignite or explode.
A spark can set off explosives, flammable gases, liquids, and solids, and oxidizers make a fire burn harder, so smoking and open flames are banned within 25 feet of a vehicle hauling Class 1, Division 2.1, Class 3, Class 4, or Class 5 material.
No one may smoke or carry a lit cigarette, cigar, or pipe on the vehicle or within 25 feet of it when it carries explosives, oxidizers, or flammables, since one spark could set off a fire or explosion.
Class 4 includes Division 4.3, materials labeled DANGEROUS WHEN WET because contact with water can make them give off flammable gas or ignite. Potassium metal is one example, and because of this reaction such materials must stay dry from loading through unloading.
The transport index is a number on the radioactive label that reflects the package's radiation level and shows how much control it calls for during shipment. It has nothing to do with weight, and drivers rely on it too, because the indexes of all packages on one vehicle are added up and limited.
Cargo tank loading and unloading must be attended by a qualified person throughout, either on site within 25 feet of the tank or from a remote control station by video or by instruments and signals when federal conditions are met, so each method listed is acceptable.
Explosives in Divisions 1.1, 1.2, and 1.3 need a tight floor with a liner of nonmetallic material or of metal that contains no iron; stainless steel is an iron alloy, so it does not qualify.
Mixing an acid with a cyanide can produce deadly hydrocyanic acid, so cyanides and cyanide mixtures may never travel with acids, corrosives, or other acidic materials. The battery acid therefore has to go on a separate load. Note that silver cyanide is a poison, not a Class 8 corrosive.
Without racks, the cylinders can ride either standing up or lying down, provided they are secured against shifting while the vehicle moves. A loose or leaning cylinder can fall, and a broken valve could release gas under high pressure.
Every question in this set has its own page with the correct answer and an explanation.
