Tuesday, December 20, 2011

You can’t beat the train. Its not like cutting in front of a car. Moron.

Today I saw this story about three people who were injured after being dragged (inside their vehicle) 250m by a moving train. They are injured but largely OK I believe.

The level crossing had excellent visibility and the train had already entered the intersection before the car moved in front of it. It was a copper ore train carrying a full load.

Some background on trains.

First, some train jargon. Impress your rail industry acquaintances!

A train is only called a “train” when it has locomotives and wagons joined together. Locomotives joined only to other locomotives are called a “Consist” (pronounced Con-sist not Cunsist). Wagons joined only to other wagons are called a “rake”. Rail people get really upset when you get that wrong.

I spent 4 years working in the railway industry and let me tell you, a train that can stop within 250m is traveling pretty slowly. Either that or its short. I am assuming that this train was pulling the largest load possible (given the available locomotive power), which is the most fuel efficient and the industry norm. Due to the low friction of railway tracks and the fact that a locomotive uses roughly the same fuel no matter what once it is rolling, the more wagons the train can pull, the more efficient. The only limiting factor is the locomotive’s ability to hold the train stationary on a hill with its weight alone. One car too many and the whole lot slides backwards and no amount of braking will stop it.

The word “shunting” was used in the news report which within the rail industry also implies very slow travel. “Shunting” refers to the slow maneuvering of the train back and forth, in and out of adjacent tracks, picking up more and more waiting rail cars. A freight train could be up to 1.8km long depending on how many locomotives are hooked up. A 500m+ long freight train is very common. Especially in mining applications.

Also, in an emergency stop, stopping within the distance of a single train length is considered to be excellent.

So a 250m stopping distance implies either a 250m train or a very slow train. Considering it was a copper ore train and that fact that ore trains are notoriously long, I’m betting on the latter.

So here’s the interesting part about what happened. The vehicle evidently made a last second dash across the tracks trying to “cut-off” the train. It is highly plausible that the driver of that vehicle thought they could make it across the tracks in time. Especially if the train was moving as slowly as it was. They may have been wrong about how fast the train was traveling but I think the real reason was less obvious than that. As for why they decided on a last minute dash, if you have ever been stuck at a crossing waiting for a train to shunt you will know it takes forever. I can understand their haste to beat the train. Stupid to the max but understandable.

The real judgment error however, was probably that they probably assumed that cutting off a train requires the same kind of “timing” employed when cutting off another car.

Bupbouwww!
(My impression of a game show buzzer. Yeah, its so real.)

When you cut off a car in the street the other driver hits the brakes. Often quite considerably, and often right from the moment that they realise how much of a fucking moron you are. Real fast in other words.

So drivers out there who are in the habit of cutting other drivers off will tend to have a very distorted “feel” for how fast the other vehicle can be traveling before they realise its best to abandon the attempt. Drivers that routinely cut off other drivers tend not to comprehend how much of a role the skill of the other driver played in avoiding disaster. They tend to assume it was their own sharp judgment and honed ( “hooned” ) driving skills that let them capitalize on a gap that other “lesser” drivers could not. Idiots.

Which is why arrogant dickheads like the ones I describe get hit by trains. A train virtually doesn’t brake when you cut them off. Their speed is essentially unchanged when they hit you and that fact is what makes trains so much harder to “beat” than cars.

It’s much like failing to notice that someone has been helping you jump across a gap every day. Then one day you make the attempt when your invisible helper is off sick and you break every bone in your body. You thought you were making the whole jump by yourself but you can really only jump half as far. Duh.

TL:DR When the other driver doesn’t (can’t) hit the brakes, even a slower vehicle, that you would normally duck in front of easily, will hit you. Plus you’re an idiot.

Monika.

Welcome!

Feasibility is an engineering based blog designed to reach other STEM people. Non-STEM people are also welcome! I try to give good advice and well-reasoned opinions but please don’t hesitate to disagree with me. This blog exists because I realised that I live in a metaphorical bubble and that simply wont do. Nup.

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