Moving Hazardous Materials by Rail
ON HAZARDOUS MATERIALS
Train accidents involving the release of hazardous materials usually make nationwide headlines because of the large quantities of product which can be released. Identifying these materials is therefore very important.
Identification aids include the placards on the outside of the transporting vehicle, marking the product itself, as well as the shipping papers.
Unfortunately, when an incident occurs, the placard could be nonexistent or burn off in a fire. In addition, to read the markings or placards requires that the officer get too close to the incident. Finally, the conductor with the shipping papers in the caboose or engine might not be immediately available.
As a result of these difficulties, the incident commander needs to use other techniques to provide clues to the hazards contained in the rail cars. One way is to obtain the consist or wheel report for the freight train. These doc uments are kept by the conductor on some trains, but they are also maintained at the sending and receiving yards.
The consist lists the freight cars in sequence, starting with the first one behind the engine and the last car in the list being the one right before the caboose. Shown on the consist are the unique serial numbers for the car and, if it contains a regulated hazardous material, the commodity name, commodity identification number, and the placard category which should apply. Thus by telephoning either the originating or the destination freight yard, information on the specific product can be obtained, However, the time it takes to obtain this information may be too long to aid the first-arriving officer in the decision-making process.
The shape of a rail car can provide basic information about the product. This ineludes such items as whether the product is a solid, liquid or a gas; whether it is a corrosive, or whether it is being transported under pressure. The initial clues involve recognizing the type of rail car transporting the product.
- A box car could contain a wide variety of products in solid, liquid or gas form. The products can be carried in metal drums, bags, boxes, plastic containers or in bulk. In addition box cars can be refrigerated, which means they are double
- walled and the void space is filled with insulation. The refrigeration unit is mounted on the outside of the car, along-with a diesel fuel tank to power the compressor. In the case of box cars, the only usable clues are the placards and shipping papers, as well as the consist.
- Tank cars can carry solids, liquids or gases (yes, tank cars can carry solids in powdered form). In liquid form, tank cars can carry from 4000 to over 40,000 gallons. The tank cars can be insulated (pressurized or nonpressurized) or noninsulated single shell (pressurized or nonpressurized). The insulated cars contain two shells of varying thickness with insulating material between the shells.
- Flatcars can carry hazardous materials in special packaging or containers. This is particularly true of radioactive materials. In a multimode operation, flatcars combine with truck transportation to carry trailers. In this mode the combination is known as a TOFC or trailer on flat car. If the trailer is carrying hazardous materials, it must be placarded.
- Hopper cars are basically designed to carry bulk solid materials. The two major hazardous materials which are carried in a hopper are oxidizers, usually fertilizer, or plastic pellets (which are not shipped as a
- hazardous material but which can cause major health problems when burning).
- Cryogenic cars carry products that have been liquefied below — 150 degrees. This type of rail car has a distinctive shape, with metal plates stretching down the upper half of the car. Although there is nothing on the car to keep the product refrigerated, the product remains cold because of the car’s insulation.
- No discussion of train transportation would be complete without a discussion of the locomotive. Remember that each one can carry up to 4000 gallons of diesel fuel. In addition, locomotives use high voltage, which can be an ignition source in an accident. It is therefore important that the unit be shut down completely after an accident.
Pressurized cars have a completely enclosed dome, while the dome is uncovered in nonpressurized cars. Insulated cars have flatter ends, while noninsulated cars have rounded ends.
One of the major problems with tank cars in a derailment involves their construction. Tank cars either have a full frame, known as a sill, which supports the I entire length of the tank or just a short sill with the tank being unsupported. No matter which type of sill is used, the tank only rests on it through a single pin. As a result, it is only the weight of the car which keeps the tank in place. Thus, in a derailment, the separation of the tank from the frame occurs very easily,
The problem with a flatcar in an accident is that the package or container separates from the car and is subjected to great stress. Other units can puncture the containers and the contents spill or leak.
Identification of the hazard is dependent on the placards, shipping papers or the consist. Sometimes the name of the container may give a clue, but this is rare.
The danger at a hazardous materials incident with a cryogenic is from the supercold temperature of the product, the high expansion rates of the liquid as it warms, as well as the poisonous or flammable characteristics of many of the specific commodities. These products include hydrogen, carbon monoxide, oxygen, argon, carbon dioxide and nitrogen.
Placards for these products vary with the commodity. For example, nitrogen shipped as a cryogen does not require any placard, while hydrogen is shipped as a flammable gas. There is no identification on these rail cars to identify the fact that they contain a cryogen. Emergency response personnel must learn to recognize these types of cars from a distance.
Care must be exercised in approaching an incident involving freight trains. If there are no placards or markings visible, the emergency response person must use other clues to determine the presence of hazardous materials. One of these techniques involves becoming familiar with the types of cars and the products they carry. By learning the shapes of these cars in a nonemergency situation, you can safely handle the incident when it occurs.
Recently, Isman took over the duties of a new position: chief of the Fairfax County, Va., Fire and Rescue Department. Chief Isman supervises over 950 career employees and 600 volunteers who man 30 stations and protect a population of 625,000-Editor.