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Silly question of the day: This afternoon a co-worker asked what happens if a passenger train gets hit by lightning, since it has a lot of metal parts that passengers can come in contact with. I didn't have an answer for him. Anybody know?
Posts: 2649 | From: California's Monterey Peninsula | Registered: Dec 2000
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There is a contact between the carbody and the axle that serves as a ground connection for the 480V HEP system.
I'd assume that lightning would strike the carbody, travel down the metal exterior sides, then through the trucks to the axles and wheels, and finally to ground through the rails.
I don't think the passengers would be harmed because electric charge travels along the exterior edge of a conductor (in this case the carbody) and the passengers aren't grounded-the ground is again either the truck or that brush that is connected to the wheels.
Posts: 286 | From: Knee deep in the retention tank | Registered: Jan 2006
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quote:Originally posted by PaulB: I don't think the passengers would be harmed because electric charge travels along the exterior edge of a conductor (in this case the carbody) and the passengers aren't grounded-the ground is again either the truck or that brush that is connected to the wheels.
Yup-- you can thank good ol' Ohm's Law for this one. Since electricity will always take the quickest (least resistive) path, and metal makes for a much better conductor than human beings (even those who have been imbibing in the Cafe Lounge), lightning *should* find its way to ground safely via the carbody.
Of course, the requisite delays that might follow, as Amtrak and Host Railroad managers all weigh in on what needs to be done before the train can proceed, might make one FEEL like they are personally conducting lightning...
Anyone have non-theoretical experience with this one?
Posts: 108 | From: Culver City, CA, US | Registered: Oct 2004
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Never had lightning hit my train, but we cruised slowly through a New Mexico thunderstorm on Train 3 once after lightning took out the signal system- awesome scenery that night.
Posts: 553 | From: Flagstaff, AZ USA | Registered: Apr 2001
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I didn't think you had that stuff out your way, Mr. Toy; or at least that is what an ex-girlfriend (ex by grace of being deceased) from Rancho Cucamonga once told me.
Posts: 9975 | From: Clarendon Hills, IL USA (BNSF Chicago Sub MP 18.71) | Registered: Apr 2002
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Lightning on ground objects go from ground to sky. So the question is what happens to passengers when an Amtrak coach lightning strikes the sky? Farraday laws says passengers will be fine. However any bird in the area will not be a happy camper.
Posts: 562 | From: Beaumont Texas | Registered: Jul 2005
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Mr. Norman, yes we do get it from time to time. But the topic came up when I told my co-worker about our trip to Denver, when we watched lightning from the diner during dinner in the Rockies. I suspected that the path would be around the carbody, just as in an automobile, but I wasn't sure enough to provide a definitive answer.
Most of our coastal California thunderstorms are pretty mild. A little here, a little there. We had several brief thunderstorms this winter, though, and a fair amount of hail to go with it. But back in the fall of '98 we had a massive thunderstorm that lasted almost 8 hours! Tourists from the midwest said they'd never seen anything like it.
Posts: 2649 | From: California's Monterey Peninsula | Registered: Dec 2000
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A couple of summers ago, I traveled through eastern Montana on the Empire Builder during a spectacular thunderstorm that lasted nearly two hours. The train was literally the tallest object on the landscape. In fact, it was the only object on the landscape for more than a hundred miles. I was amazed that it didn't attract a single lightning strike (I've experienced them while traveling on airplanes and while riding in a car; trust me, you definitely know when it happens).
I'm no scientist. But it seems that the negative polarity of the "breakfast sandwiches" served in Amtrak lounge cars finally proved useful for something after all.
quote:I'm no scientist. But it seems that the negative polarity of the "breakfast sandwiches" served in Amtrak lounge cars finally proved useful for something after all.
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Now that I think about how lightning actually works, I would think that being in a train would be about the safest possible place. In order for lightning to actually strike the earth, there has to be a hell of a static charge buildup in a localized area. And what is that running along the ground beneath your train? Two thick grounded metal conductors extending from here to (essentially) infinity. I'd be willing to bet a six-pack that any static charge developing in the earth along a rail line would be dispersed and dissipated along the track just about as quickly as it could develop.
-------------------- --------Eric H. Bowen
Stop by my website: Streamliner Schedules - Historic timetables of the great trains of the past! Posts: 413 | From: Houston, Texas | Registered: Mar 2006
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quote:Originally posted by ehbowen: Now that I think about how lightning actually works, I would think that being in a train would be about the safest possible place. In order for lightning to actually strike the earth, there has to be a hell of a static charge buildup in a localized area. And what is that running along the ground beneath your train? Two thick grounded metal conductors extending from here to (essentially) infinity. I'd be willing to bet a six-pack that any static charge developing in the earth along a rail line would be dispersed and dissipated along the track just about as quickly as it could develop.
Lightning strikes from the ground to the sky.
Posts: 562 | From: Beaumont Texas | Registered: Jul 2005
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quote:Originally posted by gp35: Lightning strikes from the ground to the sky.
Actually, lightning can take many forms. The most common strikes are sky-to-ground. Cloud-to-cloud strikes are believed to be equally common, if not more so. Ground-to-sky strikes, while well-documented, are somewhat further down on the list of typical lightning events.
Posts: 793 | Registered: Mar 2002
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Lightning is amazing just for the amount of different forms it does have. Severe weather in general can be pretty unpredictable stuff. An interesting book I found was "The Man Who Rode the Thunder," an account by a military pilot whose engine went out very high over a thunderstorm. He tells what it was like after he ejected and fell into the clouds.
Posts: 144 | Registered: Sep 2005
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