Posts tagged ‘train’
The Incident – Why Buses Open Their Door at Railroads
By Chad Upton | Editor
Although it was required by law for school bus drivers to stop at railway crossings in 1938, drivers were not required to open their door.
On December 1st of that year a gruesome accident changed that. It was a blizzard in Salt Lake City, Utah and a school bus driver stopped his bus at a railway crossing. Because of the snow, the visibility was terrible and the driver was not able to see an approaching freight train.
24 of the 40 passengers died, including the driver. According to surviving passengers, the train was broadsided without notice. Although the driver was familiar with the train schedule, the weather had delayed the train which should have passed two hours earlier. To make matters worse, the train was travelling faster than normal to make up for lost time.
Unfortunately, the same crossing saw accidents in 1995, 1997 and 2002. Thankfully, it is now closed.
The snow ultimately led to the horrific crash in 1938, but investigators wanted to know if any precautions could have prevented it. Stopping the bus and looking for trains works great when the visibility is good, but it’s useless in snow and fog. Opening the bus door (and driver’s window), allows the driver to hear trains.
Today, opening the door and/or driver side window is law in many parts of the United States and Canada. The same law is also extended to trucks that carry hazardous materials.
Some crossings do not require these vehicles to stop and they are marked with an “Exempt” sign. This is typical if the crossing is no longer active.
Railroad crossing signals do fail and there are thousands of collisions each year between trains and cars, many of which end in fatalities. Although the signals are fairly reliable, it doesn’t hurt to pay close attention when you approach railway crossings.
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Sources: The Pittsburgh Press, NSC.org, Deseret News
Photo: You Need Style (cc)
Tires Do Not Protect You During a Vehicle Lightning Strike
By Chad Upton
I’ve always heard that a car is one of the safest places to be during a lightning strike and that is true.
The tires usually get all the credit. As the story goes, tires are rubber and rubber is an insulator, so you don’t get electrocuted in the car because you’re isolated from the ground like a bird on a wire.
It’s a pretty believable story, but it’s not the truth.
If you think about it, the lightning travels thousands of feet through thin air to reach the car — it could easily continue to travel through thin air to get around a few inches of rubber tires. Compared to the power of lightning, tires don’t really provide any protection.
Trains are struck by lightning and the people inside are fine, even though trains have metal wheels, which are great conductors.
Airplanes are regularly struck by lightning in the air. In fact, the FAA estimates that each plane gets struck about once per year.
So why are people safe in these cases?
It’s all because of a principle discovered by Michael Faraday in 1836.
Faraday demonstrated that an electrical charge exists only on the exterior of a hollow conductor and not the interior. He built a wire cage, that is now know as a Faraday cage, to demonstrate that an electrical current flowing through the cage did not produce an electrical current inside the cage. When you’re in a vehicle, with a conductive exterior shell, you’re inside a Faraday cage and the electrical charge is carried around you.
Faraday cages can also be used to shield against electromagnetic radiation. Coaxial cables are common in most households for carrying TV signals. These cables are design with what amounts to be a built in Faraday cage to protect the inner copper wire from electrical noise.
Microwave ovens are also a good example of a Faraday cage. This principle protects you from exposure to microwaves by turning the inside of the oven into a Faraday cage. The mesh you see on the inside of the door is part of that cage and explains why the glass isn’t perfectly transparent.
Broken Secrets
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Sources: Wikipedia (Ground, Faraday Cage), Weather Imagery (Cars, Airplanes), Faraday Cage
Photo: jonathan mcintosh (cc)
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