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(WTKR)   Trucker: God is my co-pilot. Train engineer: Darwin is mine   (wtkr.com) divider line 57
    More: Fail, co-pilot, railroad engineers, semi-trailer trucks, CSX, trains  
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10943 clicks; posted to Main » on 05 Oct 2012 at 9:37 AM (1 year ago)   |  Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



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2012-10-05 04:53:47 PM

yet_another_wumpus: dangermen: yet_another_wumpus: You do realize that they have anti-lock brakes for trains. Can't say all of them have it, but I will be that they would pay for themselves after a single lawsuit.

Sorry, You're either a troll or a moron.

I am well aware of how train accidents happen. I lack your faith in juries and the US legal system.
And yes, there are anti-lock brakes for trains, I've interviewed at one place that makes them for subway cars.

---------------------------------------------------
Quoting from NHTSA site:
Do cars with ABS stop more quickly than cars without?
Perhaps, but that's not the main purpose of ABS. It is a system designed to help you maintain control of the vehicle during emergency braking situations, not necessarily make the car stop more quickly. ABS may shorten stopping distances on wet or slippery roads and most systems may shorten stopping distances on dry roads. On very soft surfaces, such as gravel or unpacked snow, ABS may actually lengthen stopping distances. In wet or icy conditions, you should still make sure you drive carefully, always keep a safe distance behind the vehicle in front of you, and maintain a speed consistent with the road conditions.

Trains are on rails. Given the above, what is your point again?

Freight trains have so much mass that any effort to stop wheel slip is pointless. Trains drop sand for traction when going uphill or downhill but ultimately a mile long train isn't going to matter if it had anti-lock breaks or not and it is an emergency. The expense of adding them would be extremely cost prohibitive and maintenance heavy. Just watch any rail yard and see how much of a beating all of that equipment takes. My guess is a mile long freight train would be +/- 100 feet at best with an anti-lock break setup.

Regardless, most train activity by mile of rile ridden is in fact by freight train. Most accidents are by knuckleheads hitting freight trains. Maybe passenger trains might benefit but still, a passenger train moving 25-30 mph still has enough mass to mess up anything on the road short of a steel block being shipped by trailer truck. A passenger isn't going to dump its emergency breaks and stop in 300'. Once again, the trucks have a contact area of a dime.
 
2012-10-05 05:37:41 PM
dangermen:stuff...

I wouldn't be that surprised if the point of ABS brakes is to avoid the "flat wheel spot" mentioned in this thread (in fact, it was mentioned as one of the things that can go wrong with the brakes). While that is supposed to be an expensive mistake, I expect that low-volume ABS systems would be even more expensive. Maybe they only go on passenger systems, or even just subway/commuter trains (which are going to brake hard, and often).
 
2012-10-05 07:14:34 PM

jimmyjackfunk: there was no cross bar but a regular red stop sign on either side of the tracks and old white lines on the pavement (faded from being there for years) she stopped and then proceeded across the tracks and got hit. the thing is she had her window down, the visibility was good but there was no train whistle. I wasn't there when it happened but she insists that they weren't sounding their horn.


So she thought it was a 4-way stop and the train should have stopped too?
 
2012-10-05 08:24:05 PM

foxyshadis: Heinrich von Eckardt: It's well known hitting a pickup truck will cause a train to derail and crash spectacularly, without killing the driver of the pickup.

Yet this train demolished a much larger truck, killing its driver, and somehow suffered little damage.

Something doesn't add up.

That was such a bad movie for so many reasons.

In real life, passenger trains are the only ones likely to derail in an accident. They're just not heavy enough to stay planted on the tracks against a heavy enough vehicle - an Amtrak derailing happened here just days ago because an idiot hauling fresh-picked cotton slammed right into the back of the train.

[ww3.hdnux.com image 628x443]

Non-Acela Amtrak is basically your only chance of winning the train vs truck battle.


That conductor drifting a train? bad-ass!
 
2012-10-05 10:04:38 PM

yet_another_wumpus: dangermen:stuff...

I wouldn't be that surprised if the point of ABS brakes is to avoid the "flat wheel spot" mentioned in this thread (in fact, it was mentioned as one of the things that can go wrong with the brakes). While that is supposed to be an expensive mistake, I expect that low-volume ABS systems would be even more expensive. Maybe they only go on passenger systems, or even just subway/commuter trains (which are going to brake hard, and often).


ABS works by keeping the wheels close to a non-slip condition. For steel on steel, the static friction coefficient is 0.78. In a slip condition, the friction coefficient drops to 0.57, which is 73% of static. So a skidding stop will be about 137% the length of an ABS stop. This doesn't really matter, except for how far the train will push down the tracks whatever it will hit.
 
2012-10-05 10:08:15 PM

jimmyjackfunk: Folks need to be educated I guess. Bicycles, motorbikes; no match for vehicles. Smaller economy cars, no match for bigger sedan type "old school" land yachts. most cars no match for bigger pickup trucks, and the majority of passenger vehicles on the road are no match for a tractor trailer. and finally no vehicle is a match for a train.


Don't forget "Passenger train versus freight train," which LA Metrolink has demonstrated a few times for the benefit of this generation.
 
2012-10-05 10:21:01 PM

The Beatings Will Continue Until Morale Improves: yet_another_wumpus: dangermen:stuff...

I wouldn't be that surprised if the point of ABS brakes is to avoid the "flat wheel spot" mentioned in this thread (in fact, it was mentioned as one of the things that can go wrong with the brakes). While that is supposed to be an expensive mistake, I expect that low-volume ABS systems would be even more expensive. Maybe they only go on passenger systems, or even just subway/commuter trains (which are going to brake hard, and often).

ABS works by keeping the wheels close to a non-slip condition. For steel on steel, the static friction coefficient is 0.78. In a slip condition, the friction coefficient drops to 0.57, which is 73% of static. So a skidding stop will be about 137% the length of an ABS stop. This doesn't really matter, except for how far the train will push down the tracks whatever it will hit.


I'm not completely up on ABS systems, but would ABS on an air brake that has an air pipe roughly equal to the length of a train even be feasible? I'm not getting any good ideas on how it would even work without a compressor on each car to make up the air lost in each brake application (which in an ABS system is many per second). Eventually you'd lose enough in the system to make the brakes lock anyway (since in an air brake system it is pressure loss that sets the brakes).
 
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