Stopping a Train

[Greg]

There seems to always be a plethora of train/vehicle crossing accidents.

I read somewhere that each wheel of a train has the total contact surface area with the rail of about the size of a dime. So if you have a 60 axle train, that means 120 wheels which equals 120 dimes. The area covered by 120 dimes would be less than 6 inches by 6 inches. It amazes me that the entire train has total contact with the ground of less than 6 inches square! No wonder they can't stop easily!! I would think the operation lifesaver folks could use an example like this when speaking with folks, because it sure makes it easier for me to understand and respect the physics involved with rail travel.

 

[the_traveler]

I doubt it would work! Remember, these are some of the same people that say that the train should have swerved to miss them!

 

[printman2000]

I don't really know anything about it, but I would think the weight of trains along with the forward momentum is the main obstacle to stopping quickly.

 

[the_traveler]

That, and it's steel wheels on steel rails - not the gripping rubber tires on a road! You can't stop a vehicle easily on a road with wet leaves or ice on the road either!

 

[gswager]

You'll need a reverse thruster of a jet engine but it still doesn't stop on a dime!

 

[amtrakwolverine]

Here's a Idea. Invent something that when someone is dumb enough to go around the gates it flips the car like a catapult LOL.

 

[had8ley]

There seems to always be a plethora of train/vehicle crossing accidents.

I read somewhere that each wheel of a train has the total contact surface area with the rail of about the size of a dime. So if you have a 60 axle train, that means 120 wheels which equals 120 dimes. The area covered by 120 dimes would be less than 6 inches by 6 inches. It amazes me that the entire train has total contact with the ground of less than 6 inches square! No wonder they can't stop easily!! I would think the operation lifesaver folks could use an example like this when speaking with folks, because it sure makes it easier for me to understand and respect the physics involved with rail travel.

I used to carry a rubber mallet and an empty Coke can in my grip when I gave OL presentations. The first thing I would do is smash the can with the maul and tell the audience, "That's how much chance you have running around RR gates." It usually got everybody's attention...

 

[Devil's Advocate]

I don't have much (if any) sympathy for folks who go around active gates or lights. But I can see how you could be caught off-guard on a passive crossbuck over some rural stretch of road. Especially if you're not used to seeing trains on it and the grass is high or you're just in a hurry or have the stereo playing loudly or whatever. Still, this doesn't seem to be as common as folks intentionally trying to cross active lights with crossing guards. Seems weird that this would be the case. Just another reason why driving licenses shouldn't be so easy to get. They should require substantial and repeated demonstration of both technical and practical knowledge on an annual basis and the cost of the licenses should be high enough to cover all aspects of road safety funding, including the costs of installing crossing lights.

 

[Cho Cho Charlie]

Yea, I am always the trouble maker, but IMHO, trains don't stop quickly because no one cares enough to improve their braking ability.

I don't think that a train's braking system has changed all that much in, what, 100 years?

Sure there are the challenges of physics (train mass, available friction, etc). But I can't believe that reasonable improvements can't be made. All we need, is the "incentive" for train car and locomotive manufacturers to put time and money into it.

Have you ever seen a take-off abort test of a fully loaded 747? Its wheels might glow bright red when it stops, but it does stop.

 

[battalion51]

The closest thing we've seen to improvements in braking systems in recent years is the recent testing with electronic braking systems. The air lines are still there for protective reasons and as a backup, but the problem is that the system is expensive and EVERY car and engine in the consist has to be set up for the system to work. So far there has been very limited application of this (for example on unit coal trains). I would think it'd be easy to equip the Triple Crown RoadRailer fleet with it, but what do I know?

 

[mfastx]

Here's a Idea. Invent something that when someone is dumb enough to go around the gates it flips the car like a catapult LOL.

LOL that would be brilliant.

 

[FriskyFL]

Here's a Idea. Invent something that when someone is dumb enough to go around the gates it flips the car like a catapult LOL.

Isn't that why the old-fashioned steam locomotives had a "cowcatcher"? Why not adopt the same principle, albeit large enough to dispatch a vehicle?

 

[dan72]

Here's a Idea. Invent something that when someone is dumb enough to go around the gates it flips the car like a catapult LOL.

LOL that would be brilliant.

There was a show on the Discovery Channel a couple of years ago where they experimented with something like that. They rigged a large arm on the front of the locomotive and when it sensed an impact, it would basically extend out and thrust the car out of the way. I think they got it to work pretty well, but I doubt it will see mass production anytime soon...

Dan

 

[dan72]

Here's a Idea. Invent something that when someone is dumb enough to go around the gates it flips the car like a catapult LOL.

LOL that would be brilliant.

There was a show on the Discovery Channel a couple of years ago where they experimented with something like that. They rigged a large arm on the front of the locomotive and when it sensed an impact, it would basically extend out and thrust the car out of the way. I think they got it to work pretty well, but I doubt it will see mass production anytime soon...

Dan

Here is the video. The show was called Smash Lab. As you can see, it really didn't work all that well:



Dan

 

[battalion51]

Awesome video. Most people don't realize it but pretty much every engine on the road today does have a snow plow on it which protects the train from damage, and helps move the car out of the way as much as possible. There actually was a lengthy debate in South Florida with Tri-Rail when they first started up because their Chief of Mechanical wanted snow plows on all the motors, and no one understood why. Well he showed them how it helped in collisions, and now all of the motors have a good plow and the cab cars have a small plow on them.

 

[MattW]

There's also the linear eddy brakes used on the ICE3 Trains. They induce a magnetic current in the rail and apply force to the rail itself so you don't have to worry as much about traction, but it's mainly for high speeds rather than low-speed stopping.

http://en.wikipedia.org/wiki/Eddy_current_brake

 

[Trogdor]

Yea, I am always the trouble maker, but IMHO, trains don't stop quickly because no one cares enough to improve their braking ability.

I don't think that a train's braking system has changed all that much in, what, 100 years?

Sure there are the challenges of physics (train mass, available friction, etc). But I can't believe that reasonable improvements can't be made. All we need, is the "incentive" for train car and locomotive manufacturers to put time and money into it.

Have you ever seen a take-off abort test of a fully loaded 747? Its wheels might glow bright red when it stops, but it does stop.

A fully-loaded 747 still has rubber tires on concrete, which makes it similar to an automobile when it comes to friction.

The airplane also has carbon brakes, and when they glow bright red, it tends to melt those tires.

Do something like that with a train, and you'd likely melt the axles and derail the train.

As for improving a train's braking ability, what good would it accomplish? I'd be willing to bet that most train-person or train-auto collisions occur with the victim entering the path of the train less than a second or two before the train gets there. Nothing is going to stop a train that fast, and even if you could, you'd likely risk more lives than would be lost by hitting the car/pedestrian.

If an auto is stuck on the tracks and the train's engineer can see it 1000-1500 feet away, then I would hope the driver of said vehicle would have the presence of mind to abandon the car if it truly can't be moved (and, likewise, I would hope anyone standing in the vicinity of a vehicle stuck on the tracks with a train approaching would have the presence of mind to get the hell out of the way).

In the end, you still have the laws of physics to deal with. f=ma, and in the case of a 100-car freight train, "m" is a very big number.

 

[Ryan]

Replace all the crossing gates with these:

On all 4 quadrants, problem solved.

 

[MJL]

I have a tiny amount of sympathy for people who unthinkingly stop on the tracks, waiting on a red light. I had an intersection near my home where the very wide double-tracked intersection is 2 car lengths from a busy lighted intersection. Since I know this intersection well, I always paranoidly stop WELL back of the tracks -- I know those freight trains go FLYING through there on a very regular basis. Not everybody does, especially in the left turn lane; the extra distance can make you miss the left arrow, and definitely makes the people behind you miss the arrow

I've been the first-car-in-line, a little close too close to the tracks, stopped at the red light, when those crossing gates come down. They come down in a BIG hurry, with the train coming seconds after. Really scared the beejeezus out of me.

As far as abandoning the vehicle, a single driver might be able to do that easily. If you have kids in car or booster seats -- especially a van -- no way.

 

[amtrakwolverine]

Here is the video. The show was called Smash Lab. As you can see, it really didn't work all that well:

http://www.youtube.com/watch?v=C4-ueqbuW8c

Dan

The plugs in the bag failed to release so instead of deflating the bag held firm and the car bounced off.

 

[zephyr17]

I have a tiny amount of sympathy for people who unthinkingly stop on the tracks, waiting on a red light. I had an intersection near my home where the very wide double-tracked intersection is 2 car lengths from a busy lighted intersection. Since I know this intersection well, I always paranoidly stop WELL back of the tracks -- I know those freight trains go FLYING through there on a very regular basis. Not everybody does, especially in the left turn lane; the extra distance can make you miss the left arrow, and definitely makes the people behind you miss the arrow

I've been the first-car-in-line, a little close too close to the tracks, stopped at the red light, when those crossing gates come down. They come down in a BIG hurry, with the train coming seconds after. Really scared the beejeezus out of me.

As far as abandoning the vehicle, a single driver might be able to do that easily. If you have kids in car or booster seats -- especially a van -- no way.

Why are they stopped on the tracks on the first place? It is against the law in most states, you are only supposed to cross tracks when you can clear them. I never cross railroad tracks unless I can clear them, even on branch lines I know for a fact are little used. Specific knowledge of the local branchline traffic or an intersection hosting a busy mainline shouldn't come into it. If there is a track, don't sit on it. Don't go over it unless you know you can clear it. It is both the law and ordinary prudence.

Any track can have a train any time.

 

[amtrakwolverine]

The tracks that go less then 20 feet from my window have double gates at the intersection, but if someone is THAT desperate I suppose they can just go around by driving on the sidewalk. Here the double gates go down at the same time.

 

[battalion51]

No system for crossing protection is ever going to be foolproof. Even with quad gates it doesn't stop people from sitting on the tracks when they think they have a clear crossing. The only way you can eliminate incidents is to grade separate the corridor like they've done on almost the entire NEC. You will still have incidents with trespassers, but you eliminate a lot of potential incidents by grade separating.