We all know trains can’t just stop as easily as a car. Trains cannot stop fast enough to save a life, the moving mass is huge.
Let's find out how a train stops safely and in time.
A moving train contains kinetic energy, which needs to be eliminated in order for the train to stop. Converting energy into heat is the way to do it.
A pad or a block attached to the wheels will convert the kinetic energy into heat, will slow down the wheels and eventually the train will stop.
The most used train braking systems in the world are the ones using compressed air, called "air brakes".
The air from the atmosphere is sucked in by a compressor and stored in a reservoir until future use. When the operator of the train activates the braking system, the compressed air will be distributed along the train through the braking pipe, entering the brake cylinder.
The compressed air from the brake cylinder will push up against the interior rod(part of the braking system of the train). This rod is forced into the brake pads next to it, creating friction between the two.
The process that eventually will make the train stop. But don’t forget, trains stop in their own time.
There is also an emergency brake, a separate mechanism from the conventional braking system, functioning by inducing this rapid loss of pressure, designed to stop the train as quickly as possible.
The emergency brake applies more braking force than the standard brake. It will be used as a last resort, since it can cause damage or can cause the train to derail.
Everything having to do with trains is big. Just think about the difference between a car and a large truck - the truck needs a lot more distance to stop then a car.
Every freight train, load and situation is different but the average length of a freight train is about 1 to 1¼ miles( 90 to 120 rail cars). When it's moving at 55 miles an hour, it can take a mile or more to stop after the locomotive engineer fully applies the emergency brake. An 8-car passenger train moving at 80 miles an hour needs about a mile to stop.
Just for comparison, according to the National Safety Council:
- A lightweight passenger car traveling at 55 miles an hour can stop in about 200 feet in an emergency—under perfect conditions—that is, if tires and brakes are in good condition and the road is dry.
- A commercial van or bus will need about 230 feet to stop.
- A commercial truck/trailer can stop in about 300 feet—that's the length of a football field.
- A light rail train requires about 600 feet to stop—the length of two football fields.
- Compared to this, the average freight train we mentioned above traveling at 55 miles an hour may take the length of about 18 football fields to stop.
The distance it takes to stop a train is also based on the weather.
Anyway, try to always remember that a train it's closer and faster than you think! Be cautious.