Girl, 14, struck and killed by train in Martinez

San Francisco Chronicle ^ | March 3, 2014 | Henry K. Lee

[Political Junkie Too]

Family members, friends and school officials are mourning the loss of a 14-year-old girl who was struck and killed by a train in Martinez when, according to her mother, she tried to retrieve a cell phone she had dropped on the tracks.

[snip]

The two jumped out of the way, but "she dropped her phone and went back to retrieve it," Dena Betti wrote. "She didn't judge the approach, and the train creates a vacuum, we were told, and it sucks you in. We are beyond devastated.

[Political Junkie Too]

...and the train creates a vacuum, we were told, and it sucks you in.

This is a local tragedy out here in the Bay Area.

Asking the engineers and physicists out there. Is this true?

All the news stories across the web are repeating this quote. Can a freight train really create a vacuum that can "suck you in?"

Trains roll down tracks all over the country, all the time. Trains pass train stations without stopping, all the time.

Can a freight train, loaded with rolling stock, really travel fast enough to create a vacuum strong enough to suck a 14-year-old girl into its wake?

-PJ

[Smokin' Joe]

Sad. Prayers up for the family and friends.

[SpaceBar]

she tried to retrieve a cell phone she had dropped on the tracks ...

People who are too stupid to get out of the way of hundreds of tons of moving steel deserve to be killed. Nature's built-in payback system.

[Jack Hydrazine]

I have heard of a guy riding a motorcycle too close to the trailer that was being pulled by a semi and the vacuum created pulled him in and was run over by the trailer’s wheels.

[ltc8k6]

Mythbusters was unable to find any such suction effect from a passing train, iirc.

[fieldmarshaldj]

Sad. RIP.

[Navy Patriot]

Asking the engineers and physicists out there. Is this true?

Yes, there is a wave front that collapses back to the side of the train, and it could move hundred pound girls.

[piytar]

While the language is not exactly accurate, the real-world answer is yes. (MS in Engineering here.)

[Political Junkie Too]

If the vacuum effect is real, maybe I can believe it with a semi driving at 65 mph on a highway.

That said, I doubt that a freight train was going 65mph in Martinez, CA, where the accident occurred.

Google picture of site of accident.

The track is too curvy, and the terrain is too rolling.

-PJ

[Political Junkie Too]

Thanks. I doubted the explanation because I can't imagine a train going fast enough to do that in that particular location.

I'm not saying that the train operators are using this as an excuse to cover up something else, but I do wonder how fast a train has to be going in order to create such a wave, and whether a train could have been going that fast on that part of the track.

-PJ

[piytar]

I love Mythbusters, but sometimes they screw up.

The physics is simple: Anything that size moving with significant speed disrupts the air. A LOT. The pressure wave that forms in front of the train collapses down the sides, creating low pressure. The low pressure is not a vacuum, but it can certainly suck stuff in. This is why debris will follow along with a train (or semi for that matter) that passes at a significant rate of speed.

[piytar]

Exactly.

[Jack Hydrazine]

Have no idea what the speed limit for trains is there or how you can find out.

[piytar]

Didn’t know squat about the terrain. Based on what you said, the low pressure may not have been near enough to suck her in.

[Political Junkie Too]

Look at the link to the satellite photo in post 9, and then zoom out. The area is hilly, and is the location of many oil refineries. I doubt that a train would be going that fast through that area, especially with neighborhoods in the vicinity.

How fast would a train have to go to create a vacuum wave, and could it reach that speed after coming around that curve to the west, or if it were approaching that curve going west after travelig along that bedroom neighborhood?

-PJ

[Political Junkie Too]

Correction: from the story the train was going eastbound, coming out of the curve.

-PJ

[piytar]

Too tired to do the math, but at 10 mph there would not be much of one. At 35? Maybe. At 60? Ya better believe it!

[Political Junkie Too]

Thanks. I did not know that.

-PJ

[Talisker]

People who are too stupid to get out of the way of hundreds of tons of moving steel deserve to be killed. Nature's built-in payback system.

Wow, who hurt you and left you a vicious, heartless, hypocritical, angry, gutted and burned out husk of a human being who can't feel a sad emotion if it skewered him with a ten foot harpoon and stuck him to a giant sign that said "WTF is wrong with you?"

SHE WAS A 14 YEAR OLD GIRL WHO MADE A MISTAKE. SHE DID NOT "DESERVE" TO BE KILLED.

Go buy a flashlight and look for your soul.

[ltc8k6]

I thought it was pretty good evidence that a train does not have any significant suction effects, but there is turbulence there that is unpredictable, so standing near a passing high speed train is dangerous.