Rail vehicles are different from other people movers because they are larger, heavier and carry large numbers of passengers. The injuries are more serious because the weight of the wagons varies between 25 and 60 tons. All these difficulties make our rescue work more difficult.
In an accident it is very important to order the chaos that is generated by the crash. If we have more than five people, we must triage the injuries to establish the order of extraction and we must mark triage zones to put the wounded people: zone red, yellow, green and black. Firefighters must also know what type of propulsion system the train has and how to shut off the power.
Railways have traditionally been powered by diesel fuel and/or electricity. But now new forms of energy are being developed and, in a few years, we will have hydrogen or LNG propulsion systems in trains. Firefighters must know them to create safety areas for us and the injured in case these vehicles suffer an emergency.
On 24 July 2013, an electric train was travelling from Madrid to Ferrol when it derailed 3km before reaching the station. Of the 224 people on board, 144 were injured and eight died. It was a tragedy.
When firefighters arrived at the scene everything was chaos and there were many risks for them and the people on the train. Two dangers threatened them: one was the fire in the locomotive and the other was the cutting of high-voltage power lines.
There were also more risks like people walking near the tracks and other people trying to help the injured. In this situation we would all be overwhelmed. For this reason, it is very important to be prepared, trained and have the knowledge we need about these vehicles and their energy sources.
When we talk about train propulsion systems, in many cases, we need to differentiate between vehicle on and infrastructure. For instance, in a diesel train all the elements go in the vehicle, but in an electric train, the vehicle must be seen separated from the power lines. The lines have their dangers and the vehicle its risks.
It’s important that we know that in this article we are only going to talk about propulsion systems in railways. Firefighters need to know how they generate their energy to move and the risks and dangers of these elements that these vehicles carry. Because in an emergency we must neutralize them to make a safety zone for injuries and for us. We also need the Rescue Sheets of these trains and wagons because we need to know how to close and cut the power to move them.
Passenger trains often carry many people on board and in an accident, firefighters are overwhelmed by the number of people we must attend to in a short time. For this reason, we must have training in Multiple Victim Accidents (MVI), we must carry out a correct triage and we must organize the work area for the rescue of people.
The first thing we should know is what is the propulsion system to avoid these dangers. Broken electrical installations, gas clouds, fuel spills and rechargeable storage systems are some of the risks that we must consider in a train accident.
When we are going to work around or inside these vehicles, we must know very well all the elements of propulsion systems. Current propulsion systems of trains use diesel, electricity and, in the near future, LNG and hydrogen. Or it can also be a combination of several of them.
- Monofuels:
- Steam trains: They are the oldest trains in the world. They started to work in the 19th century. They are composed of a locomotive that drags a series of wagons. The fuel to move them could be coal, oil or, rarely, wood. The steam force was the energy to move them. Functionally, it is a steam engine on wheels.
Now many of these machines are in disuse, but there are still steam trains in use around the world.
From the point of view of the propulsion system, we have the risks of the pressure of water boiled inside a boiler and the materials used to heat this water.
- Diesel: the engine of these vehicles is similar to a car, bus or truck engine but larger. It can go inside of the locomotive in the case of traditional trains or under the chassis between the wheels in the case of the railcar.
The greatest danger for us is the amount of diesel it carries for its engine. A tank can contain between 5,000 and 15,000 litres, depending on the distance that the train has to travel.
For us it’s very useful to know where the train was going, because in an emergency, when we arrive in the area, we could control this risk.
In trains with a locomotive, it is easier to know where the most dangerous elements are as they usually carry a large tank. But in the case of railcars, it is more difficult because they can carry two, three or more tanks throughout the train.
We also must be aware that these wagons carry more energy systems such as electricity and pressurized air. And they generally have emergency guidelines and procedures which should not be confused with rescue sheets.
- LNG: the railways that use this type of fuel are very similar to diesel. There are trains with large LNG tanks like the one in the photo, and there are railcars with more of them and smaller ones.
In some cases, due to the size of the fuel tank, we treat the incident as if it were a dangerous goods incident. We must create a security zone around the wagon and only authorized personnel with PPE can enter.
2. Electrically powered trains. In this class of vehicles, we have four classifications: diesel-electric, electro-diesel, hybrid and electric trains.
- Diesel-electric: This type of train has a diesel engine to power a generator that produces electricity to move the train. There is no mechanical connection between the diesel engine and the wheels. The kind of electricity used to move the traction motors can be alternating current (AC) or direct current (DC).
The use of one or the other depends on the design. For example, modern AC locomotives haver better traction and are used on trains that carry heavier loads, while DC locomotives are still used because they are cheaper to manufacture.
For us firefighters, the more important risks in an accident with this type of train are the electricity and amount of diesel in the tank.
- Electro–diesel: These propulsion systems allow a train to move with electricity or diesel, so it can use an electric motor with power lines and a diesel engine when this infrastructure does not exist. This allows trips to be made throughout a partially electrified route without changing locomotives. We can see them in trains with locomotives or railcars.
The risks of an emergency for us and passengers is the electricity and diesel of the propulsion systems. In the event of an accident and the train is powered by electricity, we must treat it as if were an electric train plus diesel risk.
- Hybrid trains: This type of propulsion system is very similar to the diesel-electric train but these have rechargeable energy storage systems (RESS). The batteries are recharged with surplus energy from the power source or energy derived from regenerable braking. The structure of these vehicles is very heavy, hence the size of the RESS package to move them is also very large.
Railcars carry several motors like this distributed throughout the train.
POWERPACK COMPONENTS
- Diesel Engine.
- E-motor/generator.
- Transmission.
- SCR catalytic converter.
- AdBlue tank.
- Drive controller.
- System control unit.
- Onboard power supply.
Currently the energy source to power the electricity storage system can be diesel, liquefied petroleum gas (LPG) or hydrogen cell fuel. Therefore, in an emergency firefighters must identify the power source on the train to establish a safety area for rescuers and injured people. Also, they must control or even neutralize the danger of the electrical supply source.
Electric train: when we speak about this class of train, we are actually talking about electrical voltage to move the train since the structure of the vehicles is very similar, basically changing the power of the motors, and therefore the voltage of the infrastructure.
The power is supplied to moving trains by a conductor cable along the track, and it may be suspended on an overhead line or below the train as a third rail. They can be direct current (DC) or alternating current (AC) power lines. On DC lines the electrical voltage varies between 600V for light trains and trams and 3,000V for medium- and long-distance trains. The voltage used on AC lines is between 25,000 and 50,000V.
In an emergency we must neutralize this risk because it is a danger for firefighters and passengers. For this, the electricity supply company must cut off the electricity supply in case of an accident and we must ensure that this has been done.
Protocols need to be developed and we regularly carry out drills to be able to verify that they work well. We must always obey five golden rules in case of an electrical accident and it’s necessary to remember them:
- Effective cut-off of all voltage sources.
- Interlocking or lockout of cut-off devices.
- Verify absence of voltage.
- Ground and short-circuit the installation.
- Signpost the work area.
- Hydrogen train: these vehicles are basically electric trains with RESS that allow them run only on electricity, but when the energy runs out, electricity is generated from the electrolysis of hydrogen.
These vehicles can circulate in electric mode when there are no power lines, that is, on traditional railways. But we can see them with pantographs to move them on electric rails and they can charge the batteries. So, they don’t need to use the hydrogen to work.
On each coach are fuel cells and roof tanks that store 99kg of hydrogen at 350 bar or 5,076psi. In the case of the locomotives, the hydrogen tanks are located in the middle of the vehicle.
Here we firefighters have two great risks: on the one hand we have the electrical danger and on the other hand we have the danger of a highly flammable pressurized gas in several tanks distributed throughout the convoy.
For us, it’s very important to know where all these elements are in the vehicles so that we can cut off the energy supply in an emergency. All this information must be made clear with symbols and work procedures under the ISO 17840 standard.
Until now, I have not been able to find rescue sheets for trains and railcars that indicate where they are and how to handle them to de-energize them. I hope that in the future the manufacturers will make them.
Bibliography:
ISO 18740 – Part 4.
Web:
https://en.wikipedia.org/wiki/Electro-diesel_locomotive
https://www.isastur.com/external/seguridad/data/en/1/1_5_6_1.htm
https://en.wikipedia.org/wiki/Railway_electrification_system#Medium-voltage_DC
https://www.imeche.org/news/news-article/could-hydrogen-trains-be-the-future-of-rail
https://www.mdpi.com/1996-1073/14/4/1144/htm
About the Author
Miguel A. Hernández Alfocea.
Formador en Rescates de Accidentes de Tráfico, Heavy Rescue Y Rescate Aéreo.
